The document describes experiments comparing the effectiveness of using lead salts alone, chelate organometallic compounds alone, and mixtures of lead salts with chelate compounds for sweetening petroleum fractions. The results showed that lead salts alone had little effect, chelate compounds required higher amounts to fully sweeten, but mixtures of lead salts with chelate compounds achieved full sweetening using lower amounts of chelate compounds, demonstrating improved efficiency.

1. * GB785043 (A)
Description: GB785043 (A) ? 1957-10-23
Improvements in or relating to the sweetening of petroleum products
Description of GB785043 (A)
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The EPO does not accept any responsibility for the accuracy of data
and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
PATENT SPECIFICATION
785,043 Date of Application and filing Complete Specification: Nov 26,
1954.
No 34400/54.
Application made in France on Dec 19, 1953.
Complete Specification Published: Oct 23, 1957;
Index at Acceptance:-Class 91, 02 c.
International Classification:-Cl Og.
COMPLETE SPECIFICATION
Improvements in or relating to the Sweetening of Petroleum Products.
We, COMPAGNIE FRANCAISE DE RAFFINAGE, a body corporate organized under
the Laws of France, of 11, rue du Docteur Lancereaux, Paris, France,
do hereby declare the invention, ' for which we pray that a patent may
be granted to us, and the method by which it is to be performed, to be

2. particularly described in and by the following statement: -
The present invention relates to a process for sweetening petroleum
fractions, and to compositions for effecting said process.
In our British Patent Specification No.
701,443 and in our co-pending British Patent Applications Nos 16038/53
and 2803/54 (Serial Nos 767587 and 782052) there are described
processes for sweetening petroleum products, and various preferred
embodiments of these processes In general, these processes comprise
effecting the desired sweeteningthat is, oxidation of mercaptan
compounds which are usually present in petroleum fractions-in the
presence of catalysts consisting of chelate organo-metallic compounds,
such asthose obtained by the action of certain Schiff's bases on a
metal salt, and in particular chelate compounds of cobalt with
Schiff's bases resulting from the condensation of salicylaldehyde with
a diamine In these processes the diamine might be aliphatic, cyclic,
aromatic or hydroaromatic The chelate compound might be prepared and
then added to the petroleum product, or might be formed in situ, and
might be used in the presence of a solvent, such as an alcohol,
ketone, phenol, or fatty acid, or in the form of an aqueous or
aqueousalcoholic dispersion The process might be worked continuously,
for instance by contacting the petroleum fractions with an excess of
chelate compound in the form of such a dispersion, the dispersion
being then separated and recycled In another alternative embodiment,
the minimum sufficient quantity of a solution of the chelate compound
was added to the petroleum fractions which then becomes sweet during
storage Usually sufficient dislPrice 3 s 6 d l solved oxygen is
present in the petroleum fractions to effect the -desired oxidation
without additional air being blown in.
It has now been found that the above described processes and their
various embodi 50 ments can be improved, in respect of the ease of
effecting a complete sweetening and of economy in the chelate compound
used, by the use of a lead salt in admixture with said chelate
compounds 55 Accordingly the present invention provides a process for
the sweetening of petroleum fractions consisting in oxidizing
mercaptans present in said petroleum fractions in the presence of a
chelate organo-metallic com 60 pound and of' a lead salt The lead
salts referred to in this specification are to be understood to
include lead salts and alkali metal plumbites.
Various preferred embodiments of the 65 process of the present
invention differ from each other principally in respect of the
conditions under which the lead salt is added to the petroleum
fractions or to the chelate compound, and in respect of the mode of 70
preparation of the chelate compound, and may be characterised by
particular combinations of these two factors Preferred embodiments of

3. the invention may comprise the features listed below, although it will
be understood 75 that the invention is not limited to the application
of these features.
The lead salt used may be one which is soluble in hydrocarbons, such
as a salt of an organic acid, a phenolate, or a mercaptide 80 The lead
salt may be added together with the chelate compound, if desired with
a solvent for the latter, to the petroleum fractions to be treated.
Alternatively, there may be added to the 85 petroleum fractions, at
the same time as the lead salt, a Schilf's base and a cobalt salt
which will produce in situ the necessary chelate compound In this
case, an aqueous alkaline solution may be present in order to 90
neutralise the acid generated by the formation of the chelate compound
The alkali-for instance, caustic soda-may be present in stoichiometric
quantity necessary to achieve neutralisation, or may, particularly in
the case of continuous processes, be present in excess in relation to
the quantity of acid generated at any particular time.
Alternatively, the petroleum fraction together with the chelate
compound already added or formed in situ, and, if desired, a solvent
therefor, may be contacted with an alkaline solution containing a lead
salt-that is, an alkaline solution of a plumbite.
As a further alternative, the petroleum fraction containing a lead
salt may be treated with an aqueous or aqueous-alcoholic dispersion of
a chelate compound, for instance, prepared in situ in the aqueous or
aqueousalcoholic medium by addition of a Schiff's base and a cobalt
salt to the dispersion medium.
The invention is further illustrated in a number of embodiments
without limitative effect in the following examples, the first five of
which are in the form of comparative experiments with the results
tabulated to demonstrate the advantages achieved by the invention In
the following examples, except Example VI, oxidation is effected by
the oxygen dissolved in the petroleum fractions themselves.
EXAMPLE I
Eight parallel experiments were conducted on a mixture of straight-run
and cracked petroleum spirit having a boiling range of 40 to 200 C and
of S G 0 730, and containing 0.024 % by weight of sulphur in the form
of mercaptans (herein abbreviated as SRSH) In the respective
experiments there were added, to portions of the petroleum spirit
mixture, the following additives, the amounts given being per litre of
the portion of petroleum spirit in question:
(a) 0 30 gms of cresol containing 10 % 45 of lead metal in the form of
lead cresolate obtained by dissolving litharge in cresol.
(b) 0 30 gms of cresol containing 10 %' of the chelate compound of
cobalt with disalicylal-1, 2 propylene diimine 50 (c) 0 50 gms of
cresol containing 10 , of the chelate compound used in (b) above.

4. (d) 0 20 grms of cresol containing 10 % of the chelate compound used
in (b) above.
(e) 0 30 gins of cresol containing 6 6 % of 55 lead metal in the form
of lead cresolate and 6.6 % of the chelate compound used in (b) above.
(f) 0 30 gms of cresol containing 10 % lead metal in the form of lead
cresolate and 6 6 % 60 of the chelate compound used in (b) above.
(g) 0 30 gmins cresol which acts as an oxidation inhibitor with
respect to the gasoline.
(h) nil (control).
The respective portions were put in storage 65 and those containing
the chelate compound and lead salt showed a progressive reduction of
their mercaptan content concurrent with the formation of a precipitate
of oxides of cobalt and/or lead which was readily separated 70 by
filtration, leaving a petroleum spirit substantially free of metal
compounds.
Table I shows comparatively the results obtained in the various
experiments in respect of the mercaptan-sulphur content remaining 75
after 24 hours, and of the stability as measured by the induction
period calculated in accordance with the standard, A S T M No D 52549.
TABLE I
Additive reagents in gms/l Content of SRSH Wt in gms of -: of spirit
(% by wt) sulphur oxidised Stability Tests by 1 gm of Induction
Chelate Lead After chelate Period Cmpnd Cresol Metal Initial 24 hrs
compound (a) 0 0 30 0 03 0 024 0 022 132 (b) 0 03 0 30 0 0 024 0 003 5
142 (c) 0 05 0 50 0 0 024 0 000 4 (d) 0 02 0 20 O 0 025 0 010 5 4 (e)
0 02 0 30 0 02 0 024 0 000 8 6 150 (f) 0 02 0 30 0 03 0 025 0 000 9
(g) 0 0 30 0 0 024 0 024 132 (h) O 0 0 0 024 0 024 58 It may be noted
that the lead salt alone as an additive is practically without effect;
that the chelate compound alone effects complete sweetening only if a
sufficient amount, of the order of 0 05 gms/I in the above tests is
used; and that the mixture of chelate compound and lead salt effects
sweetening with a consumption of 0 02 gms of chelate compound per
litre of spirit-that is, a saving of 60 as compared with the treatment
without lead It will also be noted that the process in accord 105 ance
with the present invention-for instance, test (e), improves the
stability of the petroleum spirit.
EXAMPLE II
An Iraq kerosene having a boiling range of 110 785,043 and -without 10
% of lead metal in the form of lead cresolate.
The results, shown comparatively in Table II, show the enhancement of
the sweetening effect of the chelate compound which is effected by the
presence of the lead salt.
196 to 257 C and S G 0 795, and an Iraq gas oil having a boiling range
of 1920 to 371 C and S G 0 838 were treated in the same manner as in

5. Example I with 0 30 gins/1 of petroleum fraction of cresol containing
10 % bis-(disalicylal-ethylene diimine) dicobalt, with TABLE I
Additive Reagents (gms/l of products) Chelate Cmpnd Lead Metal SRSE 5
(% by weight) Initial After 24 hrs.
Wt in gins of Sulphur oxidised by I gmin of chelate compound 0.03 0 0
030 0 012 4 7 0.03 O 03 0 030 '0 000 8 0 0.03 0 0 030 O 015 4 3 0.03 O
03 0 030 0 000 8 6 After sweetening the products are decolourised with
1 part per thousand of adsorbing earth, or by washing with 20 %
sulphuric acid The products are substantially free'of metal compounds.
EXAMPLE Ill (a) To a straight-run Iraq petroleum spirit with a boiling
range of 40 to 160 C and S.G 0 720, are added 3 cc/1 of methanol
containing 10 gins/1 of salicylalpropylene diimino cobalt.
(b) To a sample of the same spirit is added 1/40th of its volume of
the same spirit washed by an alkaline solution of lithage thus
obtaining a sample of petroleum spirit having approximately 1/40th of
its mercaptan content combined as lead mercaptide To this' 40 sample
is added 3 0 cc/1 l of methanol containing 10 gmins/l of the same
cobalt chelate compound as in (a).
(c) To a sample of the same petroleum spirit is added 0 014 gm/ 1 of
lead metal in the form 45 of lead naphthenate, and then 3 cc/l of
methanol containing 10 gms/l of the same cobalt chelate compound as in
(a).
The products are left in storage for 24 hours, and then filtered over
sand It is 50 found, as will be seen from Table III, that complete
sweetening is obtained only when the petroleum spirit has been treated
with the cobalt chelate compound in the presence of a lead salt 55
TABLE III
Additive Reagent SRSH Chelate Lead After Methanol Cmpnd Metal Initial
24 Lead Salt Present cc/1 gms/1 gms/l hours (a) 3 0 0 03 0 0 025 0 003
(b) 3 0 0 03 0 023 0 025 0 000 Lead in the form of mercaptide (c) 3 0
0 03 0 014 0 025 0 000 Lead in the form of naphthenate EXAMPLE IV
This example will illustrate embodiments in which a cobalt chelate
compound is formed in situ.
Three parallel experiments were conducted with a straight-run
petroleum spirit of Middle East origin, having a boiling range of 40
to C and S G 0 728, and containing no free sulphur In the respective
experiments there is added, per litre of spirit:(a) 0 015 gins 1, 2
dislicylal-propylene diimine and 0 0032 gins of cobalt in the form of
cobalt naphthenate.
( 5) 0 015 gins 1, 2 disalicylal-propylene diimine 0 0032 gms of
cobalt in the form of 80 cobalt naphthenate, and 0 047 gms of lead
metal in the form of lead mercaptide.
(c) 0 015 gins disalicylal-1, 2 propylene diimine O 0032 gins of
cobalt in the form of cobalt naphthenate, and 0 028 gins of lead 85

6. metal in the form of lead naphthenate.
After standing for 24 hours, the respective samples are filtered and
the mercaptan contents determined The results, as shown in Table IV,
clearly illustrate the enhanced 90 activity, due to the presence of
the lead salt, of the chelate compound formed in situ by the action of
the' Schiff's base on the cobalt salt.
Product treated Iraq Kerosene Iraq Gas Oil 785,043 785,043 TABLE IV
Additive Reagents SRSH (% by wt) (grnsll of Spirit) Wt in gms of
sulphur oxidised Lead Salicylal Cobalt After by 1 gin of chelate Metal
diimine Naphthenate Initial 24 hrs compound.
(a) O 0 015 0 0032 0 025 0 015 4 0 (b) 0 047 0 015 0 0032 0 025 0 003
8 8 (c) 0 028 0 015 0 0032 0 025 0 004 8 4 EXAMPLE V Example IV, but
in the presence of 25 cc/1 of In this example also, the cobalt chelate
spirit of 10 % caustic soda The results compound is formed in situ
obtained for the respective quantities of The same petroleum spirit as
in Example IV additive reagents used are summarised in is treated with
the same additive reagents as in Table V: TABLE V
Additive Reagents (ginsl/1 of spirit) Sn SH (% by wt) Wt in gms of
Lead Salicylal Cobalt 10 % After sulphur oxidised Metal diimine
(Naphthenate) Na OH Initial 24 by 1 gin chelate (gins) (gms) (gins)
(cc) hrs compound 0 0 0075 0 0016 25 0 025 0 010 12 0.047 0 0075 0
0016 25 0 025 0 003 17 5 0.028 0 0075 0 0016 25 0 023 0 002 16 5 0.028
0 0150 0 0032 25 0 025 0 0005 10 0 0 015 0 0032 25 0 025 0 004 8 4
These data show that in the absence of a lead salt, the mercaptan
content is only moderately reduced On the other hand, the mixture of
the lead salt with the cobalt chelate compound effects the reduction
of the mercaptan content to a copper number of 4 without additional
consumption of chelate compound, and even effects substantially
complete sweetening The favourable action of the caustic soda in this
case when a cobalt chelate compound is formed in situ will be noted by
a comparison of these results with those in Example IV.
EXAMPLE VI
In a continuous process, there were injected into a petroleum spirit
of boiling range of 40 to 2005 C and S G 0 730, successively per cubic
m thereof, 7 5 gins of disalicylal-1, 2 propylene diimine and 1 6 gins
of cobalt in the form of cobalt acetylacetonate to form a cobalt
chelate compound.
The resulting mixture was contacted in a mixer with simultaneous
injection of air with 1/10th of its volume of 10 % caustic soda in
which were dissolved 3 5 gins/1 of litharge.
The aqueous phase is separated in a decanting vessel and recycled to
the mixer.
In this manner were treated 70 litres of a petroleum spirit containing
0 025 %c by weight of sulphur in the form of mercaptans, and having

7. had added thereto 100 cc of Na OHplumbite solution.
The petroleum spirit product obtained had a copper number of 3.
EXAMPLE VII
An aqueous dispersion of the cobalt chelate compound of disalicylal-1,
2 propylene diimine is prepared by adding stoichiometric 70 quantities
of soda, disalicylal-1, 2 propylene diimine and cobalt nitrate, to a
mixture of %, by volume of water and 10 % by volume of a commercial
solution of the wetting agent marketed under the Registered Trade Mark
75 "Teepol " In this manner, a stable aqueous dispersion containing 1
% of the chelate compound was obtained.
One litre of straight-run Iraq petroleum spirit having a final boiling
point of 200 C 80 and S G 0 720, and containing 0 025 % by weight of
sulphur in the form of mercaptan, is agitated for 3 minutes with 3 cc
of the above-described 1 %, dispersion of chelate compound, and is
then allowed to settle After 85 standing for 24 hours, the mercaptan
content had dropped to 0 012 % O SRSH.
A parallel experiment was conducted with the same quantities of
reagents but in which previously 0 02 gm/l of lead metal in the form
90 of lead cresolate had been added to the petroleum spirit After 24
hours, the petroleum contained only 0 002 % S Rs H.
EXAMPLE VIII
An aqueous-alcoholic solution of the chelate 95 compound of cobalt
with disalicylal-1, 2 propylene diimnine containing 6 gins/1 of the
chelate compound and 100 cc of methanol per litre, is prepared.
(a) 250 cc of this solution is used to treat 100 in hydrocarbons.
4 A process as claimed in claims 1 or 3, characterised in that the
chelate compound is introduced into the petroleum fraction in solution
in a solvent miscible with the said 70 petroleum fraction, such as an
alcoholy, a ketone, a phenol, or a fatty acid, said solution also
containing the lead salt soluble in hydrocarbons, such as the salt of
an organic acid, a phenolate or a mercaptide 75 A process as claimed
in any one of claims 1 to 3, characterised in that the petroleum
fraction to which a cobalt salt, a Schif F's base and the lead salt
have previously been added, is brought into contact with an aqueous 80
alkaline solution.
6 A process as claimed in any one of claims 1 to 3, characterised in
that the petroleum fraction to which a cobalt salt and a Schiff's base
have been previously added, is 85 brought into contact with an
alkaline solution containing a mineral salt of lead.
7 A process as claimed in claims 1 or 3, characterised in that the
petroleum fraction to which a lead salt has previously been added is
90 treated with an aqueous dispersion of a chelate compound of cobalt.
8 A process as claimed in claim 7, characterised in that the said
dispersion is prepared by adding a cobalt salt and a Schiff's 95 base

8. to an aqueous solution of a surface active agent.
9 A process as claimed in claims 1 or 3 characterised in that the
petroleum fraction, to which a lead salt has previously been 100
added, is treated with an aqueous-alcoholic dispersion of a chelate
compound of cobalt.
A composition to be added to a petroleum fraction, for the purpose of
sweetening the same, consisting of a mixed 105 solution of a chelate
organo-metallic compound and a lead salt.
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* GB785044 (A)
Description: GB785044 (A) ? 1957-10-23
Electro-plating apparatus of the rotary-barrel type
Description of GB785044 (A)
PATENT SPECIFICATION
Inventor:-ALFRED JAMES LESTER NASH.
Date of filing Complete Specification: Nov 23, 1955.
Application Date: Dec 15, 1954 No 36268154.
Complete Specification Pitliilied: Oct 23, 1957.
Index at Acceptance:-Class 41, A 1 A.
International Classiiication:-C 23 b.
COMPLETE SPECIFICATION.
Electro-Plating Apparatus of the Rotary-Barrel Type.
We, R CRUICKSHA Nic LIMITED, of Camden Street, in the City of
Birmingham 1, a British Company, do hereby declare the invention, for
which we pray that a patent may be granted to us, and the method by
which it is to be performed, to be particularly described in and by
the following statement:-

9. This invention has for its object to provide in an improved form an
electroplating apparatus of the rotary-barrel type.
An apparatus in accordance with the invention comprises a frame
adapted to be supported on a tank and movable vertically into and cut
of the tank, a pair of barreldriving rings adapted to be secured to
the ends of the barrel, rollers on which the said rings are suspended,
driving mechanism for the rollers comprising a source of motion
mounted on the tank and gearing mounted on the frame and detachably
engageable with the said source of motion, and steady pieces supported
by the frame for engagement with the ends of the barrel.
In the accompanying drawings:Figure 1 is a sectional front elevation
of an apparatus embodying the invention; and Figure 2 is an end
elevation; Figure 3 is an end elevation of the lower portion of one of
the depending side members of the frame; Figure 4 is an end view of
one of the barrel-driving rings; Figure 5 is a front elevation of an
alternative arrangement of the barrel-driving mechanism.
Referring to Figures 1-4 of the draw; ings, the frame consists of a
horizontal upper member a, and a pair of depending side members b The
upper member is adapted to extend across and to be supported on the
upper edges of a tank c, by a pair of laterally extending cylindrical
pegs d lPrice 3 s 4 g 785,044 secured at a distance apart on each end
of this member and arranged to be supported by forked sockets e
secured to the ends of the tank At the underside of and parallel with
the upper member of the frame is supported a shaft f, this being
carried by bearings g attached to the said member On this shaft is
secured a pinion h which engages another pinion i on a shorter shaft j
which is also carried by the said member, and which extends beyond one
end of the tank On the outer end of the second shaft j is secured
another pinion k which engages a pinion m driven by an electric motor
n through a belt o and pulleys p, and reduction gearing q, the motor
and reduction gearing being supported on a bracket r secured to the
outer side of one of the end walls of the tank The arrangement is such
that when the frame is in its operative position, the end pinion k on
the shaft j engages the motor-driven pinion and so transmits motion to
the shaft f But when the frame is raised the said pinion on the shaft
j is raised out of engagement with its associated driving pinion
Raising and lowering of the frame is effected in any convenient manner
such as by an overhead lifting tackle attached to a hook on the upper
member of the frame.
On each end of the shaft f is secured a roller S and on these rollers
are suspended a pair of coaxial rings t which are secured to the ends
of the barrel u by diametrical straps v and screws as shown in Figures
1 and 4 The rollers and rings may cooperate frictionally, but if
desired each roller may be a toothed pinion, in which case each ring

10. is internally toothed.
To prevent lateral swinging of the barrel relatively to the rollers,
when the barrel is being rotated, there is formed in the centre of (G
5 753 so 785,044 each end of the barrel ends a hole into which enters
one end of a steady piece W shaped as shown in Figures 1 and 3 The
said end of the steady pieces is of cylindrical form A 5 and is made
of rather smaller diameter than the hole Tihe other end of the steady
piece is of rectangular form and enters into the adjacent side member
b of the frame, the said member being constructed from a pair of parts
which form between them a guide for the said end of the steady piece
as shown in Figure 3 The arrangement is such that the steady pieces
serve only to prevent swinging of the discs and barrel when in motion,
and sufficient clearance is provided between them and the holes to
permit at all times effective driving contact between the above
described rollers and rings, irrespective of normal wear or the 2 '
accumulation of deposits on the rollers or disc flanges.
The cathodes consist of electrically insulated flexible conductors x
which are inserted into the barrel through central holes -5 in the
steady pieces The free ends of the conductors lie in contact with the
lower part of the barrel, and their outer ends are secured to
terminals on the upper member of the frame The anodes (not shown)
con3, sist of a series of metal plates, either flat or bent to a
semi-circular form suspended by means of metal hooks from suitably
placed anode rods.
In an alternative form of that part of the 3.5 barrel-driving
mechanism which is mounted on the frame, the arrangemnent shown in
Figure 5 may be used In this case the shaft j which receives motion
from the motor through the pinion k, is extended and is provided with
two pinions i which engage pinions hz, the latter being secured to a
pair of short shafts f which carry the rollers s.
By this invention the mechanism required for rotating the barrel in
the tank is provided in a very simple and robust form which is
unaffected by normal wear or by the accretion thereon of metallic or
other deposits derived from the tank.
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11. * GB785045 (A)
Description: GB785045 (A) ? 1957-10-23
Purification of terephthalic acid
Description of GB785045 (A)
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The EPO does not accept any responsibility for the accuracy of data
and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
COMPLETE SPECIFICATION
Purification of Terephthalic Acid
We, IMPERIAL CHEMICAL INDUSTRIES
LIMITED, of Imperial Chemical House, Millbank, London, S.W.1, England,
a British
Company, do hereby declare the invention, for which we pray that a
patent may be granted to us, and the method by which it is to be
performed, to be particularly described in and by the following
statement :
This invention relates to the purification of terephthalic acid.
In the preparation of terephthalic acid by the oxidation of
para-substituted aromatic compounds such as para-xylene, the crude
terephthalic acid contains small quantities of coloured impurities.
When using terephthalic acid in the manufacture of fibre and
film-forming polyesters it is essential that the terephthalic acid
used be free of coloured impurities, as far as is practically
possible, in order to obtain polyesters having good colour.
According to the present invention, we provide an improved process for
purifying crude terephthalic acid, which comprises heating
terephthalic acid under pressure with water containing an oxidising
agent having no oxidising effect on the terephthalic acid itself,
preferably a manganese or chromium compound, continuing the heating
until solution occurs, cooling the resultant solution and allowing
terephthalic acid to crystallise out.

12. In the preferred process of our invention, we heat the crude
terephthalic acid in water containing the oxidising agent to a
temperature above 200 C., as the solubility of terephthalic acid in
water above 200 C. increases rapidly. We have found that permanganic
acid derivatives, especially potassium and sodium permanganates,
chromic acid and derivatives of chromic acid, or manganese dioxide or
mixtures of these compounds are very suitable oXidsing agents as they
are readily available and have no effect on the terephthalic acid but
only on the impurities.
If desired, a first purification may be made using a simple
recrystallisation of the crude acid from water under pressure before
subjecting the terephthalic acid to a further purification by the
process of our present invention.
We have also found that if the crude terephthalic acid is first
treated in aqueous solution under pressure with a reducing agent,
which does not reduce the terephthalic acid itself, the impurities in
the terephthalic acid are more readily oxidised by the subsequent
oxidation treatment As examples of reducing agents, we have found such
substances as sodium hyposulphite, titanous sulphate, sulphur dioxide,
hydrogen sulphide, nascent hydrogen and phosphorous acid are very
suitable.
A sample of crude terephthalic acid was twice crystallised from a 4%
solution in water at 2400 C. The optical density of the product in 4%
ammonia solution was 0.36. The optical density is an arbitrary figure
based on 0.00 for 4% ammonia alone and measured at a wavelength of 380
x 10-r centimetres.
The following examples, in which all percentages are by weight
illustrate the superior results obtained by, but do not limit, our
invention:-
EXAMPLE 1
A further sample of the same crude terephthalic acid referred to
hereinbefore was twice crystallised from a 4% solution in water at 240
C. but on the second occasion 0.1% potassium permanganate was added to
the water and the solution made slightly acid by the addition of 1%
sulphuric acid. The optical density of the product was 0.26.
EXAMPLE 2
The process of Example 1 was repeated using 0.1% manganese dioxide
instead of potassium permanganate. The optical density of the derived
terephthalic acid was 0.30.
EXAMPLE 3
The process of Example 1 was repeated using 0.1% sodium permanganate.
The optical density of the product was 027.
EXAMPLE 4
The process of Example 1 was repeated using a solution containing 0.1%

13. of sodium dichromate instead of the permanganate. The optical density
of the derived terephthalic acid was 0.30.
EXAMPLE 5
The process of Example 4 was repeated using 0.1% potassium dichromate.
The optical density of the derived terephthalic acid was 0.29.
EXAMPLE 6
The process of Example 4 was repeated using 0. 1% chromium trioxide in
place of sodium dichromate. The optical density of the derived
terephthalic acid was 0.31.
EXAMPLE 7
Another sample of the crude terephthalic acid used in Example 1 was
first crystallised from water in a 4% solution, the solution also
containing 0.1% titanous sulphate. The optical density measured as
before gave a value of 1.5. When the product was crystallised a second
time from 0.1% potassium permanganate solution, the resultant optical
density was 0.04.
EXAMPLE 8
The process of Example 7 was repeated using nascent hydrogen as the
reducing agent which was generated from zinc and sulphuric acid. The
optical density of the derived terephthalic acid was 0.09.
EXAMPLE 9
The process of Example 7 was repeated using 0.1% sodium hyposulphite
in place of titanous sulphate followed by oxidation using 0.1%
potassium dichromate in place of potassium permanganate. The optical
density of the derived terephthalic acid was 0.07.
EXAMPLE 10
The process of Example 9 was repeated using 0.1% of stannous chloride
in 1% hydrochloric acid as the reducing agent. The optical density of
the derived terephthalic acid was 0.15.
EXAMPLE 11
The process of Example 9 was repeated, the terephthalic acid being
initially crystallised from water containing 0.1% of sulphur dioxide.
The optical density of the derived terephthalic acid was 0.28.
EXAMPLE 12
The process of Example 9 was repeated, the terephthalic acid being
initially crystallised from 1% phosphorus acid. The subsequent
oxidation was with potassium permanganate.
The optical density of the derived terephthalic acid was 0.03.
Although the reducing agent when combined with the oxidising agent,
gives such a useful improvement we have found that no appreciable
improvement is obtained using a reducing agent on its own.
The improvement obtained in the colour of the terephthalic acid is
clearly reflected in the improved colour of polyesters made from the
terephthalic acid.

14. What we claim is: -
1. A process for purifying terephthalic acid which comprises heating
terephthalic acid under pressure with water containing an oxidising
agent having no oxidising effect on the terephthalic acid itself,
continuing the heating until solution occurs, cooling the resultant
solution and allowing terephthalic acid to crystallise out.
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* GB785046 (A)
Description: GB785046 (A) ? 1957-10-23
Acetone soluble copolymers
Description of GB785046 (A)
A high quality text as facsimile in your desired language may be available
amongst the following family members:
DE1063805 (B) FR1138947 (A) US2855389 (A)
DE1063805 (B) FR1138947 (A) US2855389 (A) less
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0,,
Cs & 'l V

15. PATENT SPECIFICATION
Inventor: ANTHONY SPARKS Date of filing Complete Specification: Nov
23, 1955.
Application Date: Dec24, 1954 No 37388/54 7 Complete Specification
Published: Oct 23, 1957.
Index at acceptance:-Class 2 ( 6), P 8 D( 3 A: 8), P 8 (F 1: K 10), P
8 P 1 E( 1: 3), P 8 P 2 (AS: X), P 1 OD( 1 A: 2 A; 8), P 10 F 1, PI O
K( 8; 10), PI O P 1 E( 1:3), P 10 P 2 (A 5: X).
International Classification:-C 08 f.
COMPLETE SPECIFICATION
Acetone Soluble Copolymers We, THE DISTILLERS COMPANY LIMITED, a
British Company, of 12, Torphichen Street, Edinburgh 3, Scotland, do
hereby declare the invention, for which we pray that a patent may be
granted to us, and the method by which it is to be performed, to be
particularly described in and by the following statement: -
The present invention relates to, improvements in or relating to the
production of vinylidene chloride/acrylonitrile copolymers.
In particular it relates to the production of such copolymers which
are readily dissolved in acetone which May, if necessary, be heated to
aid the solution of the polymer.
lit has been stated that when vinylidene chloride and acrylonitrile
are copolymerised in a system in which the monomers are present in
aqueous emulsion or suspension, the initial ratio of water to total
monomers being between 5:1 and 10:1 by weight and the initial molar
ratio of vinylidene chloride to acrylonlitrile being between 3: 1 and
1: 3, acetone-soluble polymers of good quality can be obtained without
the necessity of adding the acylonitrile in stages or progressively
removing unreacted vinylidene chloride From such mixtures the
resultant acetone-soluble copolymers have contained proportions of
combined vinylidene chloride ranging from less than 50 % to over 80 %
by weight.
It has further been stated that acetonesoluble copolymers are obtained
by replacing a part of the vinylidene chloride with vinyl chloride in
the copolymerisation of vinylidene chloride and acrylonitle Copolymers
containing from 10 to 60 % by weight of combined vinyl chloride and 50
to 20 % by weight of combined acrylonitrile, the remainder being
vinylidene chloride are said to be acetonesoluble.
It has now been found that in the preparlation of vinylidene
chleride/acrylonitrile copolymers which are acetone-soluble emulsion
polymteri ation techniques although giving lPrice Ad g Q good
products, suffer from the practical disadvantage that the recovery of
the product is comparatively difficult owing to the emulsified form in
which lit is produced In particular the emulsion has to be broken
before the product can be recovered by normal methods and moreover it

16. is difficult to ensure removal of the emulsifying agent.
The usual suspension polymerisation procedures, in which the
polymnerisation takes place in the dispersed monomer-phase, give rise
to polymers in the form of beads which are therefore easily
recoverable in a pure state However, they suffer from the disadvantage
that ithey 'are not completely homogeneous They contain small portions
of material which are not easily dissolved in acetone and, in some
cases, are insoluble in acetone.
An object of the present invention is to provide an improved process
for the production of acetone-soluble copolymers from vinylidene
chloride and acrylonitrile A further object is to provide a process in
which the relarive proportions of the two monomers entering the
copolymer may be readily controlled.
Accordingly the present invention provides a process for the
production of copolymers in the form of beads which comprises
suspending a monomeric mixture comprising vinylidene chloride and
acrylonitrile in such proportions that the resultant copolymer is
soluble in acetone, throughout an aqueous phase containing an
inorganic suspension stabilisers and sufficient quantities of a
dissolved salt to reduce subseantally the solubility of acrylonitrile
therein, and polymerising the suspended monomeric mixture at an
elevated temperature with the aid of a monomer-soluble polymerisation
catalyst.
The vinylidene chloride and acrylonitrile May be present in any
proportions which are knoiwn to give acetone-soluble products, for
instance, the proportion of combined vinyl785046 v I q G ' 785,046
idene chloride in the copolymer may range from less than 50 % to over
80 % by weight If desired, some of the vinylidene chloride may be
replaced with vinyl chloride or some other suitable copolymerisable
monomer to give ternary copolymers which are soluble in acetone When
the third component is vinyl chloride acetone soluble copolymers
contain, for instance, 10 to 60 % by weight vinyl chloride units and
50 to 20 % by weight acrylonitrile units, the remainder being
vinylidene chloride units The solubility of a copolymer of vinylidene
chloride and acrylonitrile in acetone depends, inter alia, upon its
constitution It is also well established that the constitution of a
copolymer depends not only on the proportion of the monomers present
in the monomer mixture from which it is formed, and their relative
reactivities, but also on the degree to which the copolymerisation is
allowed to proceed It is thus possible to vary the acetone solubility
of a copolymer produced by the process of the present invention from a
given monomer mixture by varying the degree of polymerisation which
occurs.
From the wide ranges of acetone-soluble copolymers which can be

17. produced by the process of the present invention particularly valuable
copolymers for the production of films and fibres are those consisting
essentially of vinylidene chloride and acrylonitrile units in which
the latter are present in a proportion by weight of (about 40 % to 50
%.
If the proportion of acrylonitrile units is increased above about 50
%, the acetone solubility of the product is reduced, while if it is
reduced below 40 % those advantageous properties of the copolymer
which make it valuable in the manufacture of films 'and fibres are
diminished Particularly valuable copolymers contain about 480 % by
weight of acrylonitrile units.
The process of the present invention is particularly useful for the
preparation of copolymers having acrylonitrile contents between 40 and
50 % by weight and it is found that there is no need to adopt special
techniques such as adding the components at different rates to the
polymerising suspension in order to obtain good yields of the desired
products They are formed most economically by the process of the
present invention with the minimum wastage of unpolymerised monaers by
starting with 100 parts by weight of a monomer mixture containing from
50 to 60 parts by weight of vinylidene chloride and from 50 to 40
parts by weight of acrylonitrile A preferred monomer mixture contains
about 55 parts by weight of vinylidene chloride and about 45 parts by
weight of acrylonitrile.
The volume of the aqueous phase in relation to the monomer mixture can
be varied as is well known in connection with aqueous suspension
polymerisation systems Most conveniently the polymerisation system
should contain from 1 to 3 volumes of aqueous phase per volume of
monomer mixture.
Any of the known inorganic suspension stabilisers which have hitherto
been suggested for 70 use in the polymerisation of vinyl monomers may
be used in the process of the present invention provided that it does
not react with, or become inactivated by, the dissolved salt present
in the aqueous phase Particularly good 75 results are obtained when
finely divided magnesium hydroxide is used as suspension stabiliser
The quantity of stabiliser used may be varied considerably as is well
known in the art of suspension polymerisation Generally it 80 is
preferred to use as small a quantity of stabiliser as possible having
regard for the stability of the suspension and, for instance, when
magnesium hydroxide is employed, the preferred weight of stabiliser is
about 0 5 % 85 by weight on the water in the aqueous phase which is
present in about 1 to 3 volumes per one volume of monomer mixture.
It is known that the addition of soluble salts such as sodium chloride
to water re 90 duces the amount of acrylonitrile which can be
dissolved therein at any given temperature.

18. In the process of the present invention sufficient quantities of such
a salt are added to the aqueous phase of the suspension polymnerisa 95
tion system to reduce substantially the solubility of the
acrylonitrile therein It is preferred that the amount of the salt
added shall be such that the solubility of the acrylonitrile in the
aqueous phase at the temperature of the 100 polymerisation is at least
halved The precise amount of salt employed will depend on the nature
of the product it is desired to produce and polymerisation conditions
employed; by varying the amount of salt employed consider 105 able
control of the copolymerisation reaction and product can be achieved.
Often it is convenient to use a nearly saturated salt solution but
care has to be taken to ensure that no difficulties arise due to
crystal 110 lisation of the salt from the aqueous phase either during
the polymerisation or subsequently during the processing of the
resultant bead suspension should the temperature thereof be reduced
Particularly good results 115 are obtained by using sodium chloride as
the salt dissolved in the aqueous phase.
The copolymerisation of the monomeric mixture containing the
vinylidene chloride and the acrylonitrile is brought about in the
usual 120 manner by the addition thereto of a monomer-soluble
polymerisation catalyst after which the mixture is heated By ia
monomersoluble catalyst is meant a catalyst which is considerably more
soluble in the monomer 125 than in the water phase The preferred
catalysts are substantially insoluble in the aqueous phase and, as
examples, may be mentioned the substantially water-inseluble organic
peroxides such as benzoyl peroxide, ortho-chlorbenzoyl 130 cess of the
present invention.
EXAMPLES 1-8.
In each of these examples 275 grams of vinylidene chloride were mixed
with 225 grams of acrylonitrile and 1 0 % of benzoyl peroxide was
added This oil phase was dispersed in 1250 millilitres of water
containing varying quantities of dissolved sodium chloride (see tables
below) and 0 5 % by weight on the water present of magnesium hydroxide
which had been formed in situ by the addition of sodium hydroxide to
magnesium chloride in solution The suspension Was maintained by the
action of a stirrer rotating at 400 r.p m and polymerisation was
brought about by heating the suspension to an elevated temperature and
for the periods indicated in the table below In all the examples
nitrogen was used to displace oxygen from the polymerisation vessel
and in some cases the polymerisation was carried out under super
atmospheric pressures.
At the end of the polymerisation period the suspension was discharged
from the reaction vessel and well washed with water The beads were
then washed with dilute hydrochloric acid solution and stirred for 30

19. minutes to remove any residual magnesium hydroxide The beads were
finally washed with water until free from chloride ions and then dried
in a vacuum oven at 50 to 60 C The results obtained are shown in the
following table:
peroxide and aluryl peroxide.
The temperature at which the copolymerisation is carried out may be
varied considerably depending ion the rate of polymerisation required,
the amount of polymerisation catalyst employed and the physical
properties it is desired that the final product should possess.
If temperatures above the boiling points of any of the components of
the system are used, super atmospheric pressures have to be employed
in order to maintain the liquid phases.
Most suitably tthe polymerisation is carried out at a temperature it
the range 40 to 90 ' C.
As is customary in polymerisation reactions it is preferred to carry
out the polymerisation in the absence of molecular oxygen and this is
most suitably achieved by displacing the air in the polymerisation
vessel with an inert gas such as nitrogen Preferably the inert gas is
employed at a super atmospheric pressure.
The copolymer beads produced by the process of the present invention
are recovered and washed by any of the usual techniques.
The products are particularly useful for the production of acetone
solutions from which films and fibres of the vinylicdene chloride/
acrylonitrile copolymers can be prepared by any of the known wet
casting or spinning techniques.
The following examples illustrate the proWt of Na Cl Nitrogen
Polymerisation % by weight in aqueous pressure of acryloExample phase
in in lbs / Temp Time Yield nitrile units grams sq in C Hrs % in
copolymer 1 475 Atmos 70 4 74 6 43 9 pheric 2 425 Atmos 70 4 84 3 44 4
pheric 3 425 Atmos 65 4 85 44 0 pheric 4 400 Atmos 70 4 82 1 45 6
pheric 400 20 70 5 81 7 44 6 6 400 40 70 2 5 78 9 44 3 7 400 60 70 5
82 9 44 9 8 400 Atmos 65 5 80 1 44 5 pheric In all the above examplest
the product was in the form of yellowish-white beads which readily
dissolved in acetone to give solutions from which films and fibres
were produced by known procedure The yield is indicated in a
percentage of the theoretical yield.
When the same relative quantities of monomers were copolymerised under
similar con785,046 ditions using a suspension process in which an
inorganic stabiliser was employed in the absence of a dissolved salt
in the aqueous phase or in which an organic stabiliser was employed
inferior products were obtained which were not so completely soluble
in acetone and which had slightly lower acrylonitrile unit contents
Such products were also inferior with regard to their spinning
properties.

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* GB785047 (A)
Description: GB785047 (A) ? 1957-10-23
Anhydrotetracycline compounds
Description of GB785047 (A)
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and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
COMPLETE SPECIFICATION Anhydrotetraeycime Compound
We, CHAS. PFIZER & CO., INC., a corporation organized and existing
under the laws of the State of Delaware, United States of
America, located at 11 Bartlett Street, Brooklyn 6, State of New York,
United States of
America, do hereby declare the invention, for which we pray that a
patent may be granted to us, and the method by which it is to be
performed, to be particularly described in and by the following
statement :-
This invention is concerned with a method of converting certain
antimicrobially active agents to the corresponding anhydro compounds.
This invention is also concerned with the products obtained by this
reaction. The prcduct orrnea by thel loss of one molecule of watsc
from the structural unit of certain pclycyclic oxygenated compounds

21. from the class generally referred to as tetracyclines.
It has now been found that not only does oxytetracycline undergo this
unique dehydration reaction, but in exactly the same manner
Anhydrodesdimethylaminooxytetra
cycline
Anhydrodiacetyloxytetracycline Anhydrodesdimethylaminodesoxyoxy-
tetracycline
Anhydrodesdimethylaminochlortetra
cycline Anhydrodesdimethylaminotetracycline
Anhydromethomycin Anhydroisodesdimethylaminooxytetra-
cycline
The dehydration reaction of the present invention may be brought about
by dehydrating agents, particularly acidic compounds.
For some unknown reasons this results in the formation of the new
compounds which have appreciably different types of activity against
microorganisms from that of the parent compounds. This result is not a
mere certain other compounds may be dehydrated to yield new products
which are microbiologically active. Most unusual is the fact that
there is often appreciable change in the antimicrobial spectrum of the
product formed as compared to the starting materials. This change in
the nature of the spectrum may be due to a characteristic change in
the structural configuration of the product as compared to the
starting materials.
In the following table is given the names of the anhydro compounds
(referred to herein as"anhydrotetracycline compounds") together with
the apparent structure of some of these compounds which are made by
the process of the present invention :
<img class="EMIRef" id="026415687-00010001" />
R1 R2 R3 R4
H OH H OH
CH3)2 OAc H OAc
H OH H
H H Cl OH
H OH H CH,,
H H Cl OH
H H H OH
H OH H CH3
H OH H OH
(trans) quantitative change, but a change in which the product is
active against organisms which are but slightly affected or not
affecte at all by the parent compound. Furthermore, the dehydrated
compounds have somewhat different chemical properties from the parent
products. This is particularly true with respect to stability of the
new compounds which often tend to be higher than that of the parent

22. compounds.
Among the agents which are effective in bringing about the dehydration
process of this invention are mineral acids such as sulfuric acid,
hydrochloric acid, hydrobromic acid, phosphoric acid and various
anhydrides of these compounds. Acid salts such as potassium acid
sulfate, sodium acid sulfate, and sodium dihydrogen phosphate are also
effective. Organic acids are found to be effective for bringing about
this process, such as benzene sulfonic acid, toluene sulfonic acid and
chloracetic acid. The reaction may be effected in aqueous solutions in
the presence of the various acid dehydrating agents, but it is often
preferred to use conditions involving the presence of a minor
proportion of water or none at all in the reaction mixture. The use of
a stable polar organic solvent is particularly effective with acid
dehydrating agents. Among the combinations which are favored are
anhydrous hydrogen chloride in menthanol, anhydrous hydrogen chloride
in acetone, concentrated sulfuric acid in dimethylformamide and
hydrogen chloride in acetic acid. It is obvious that care must be
exercised in conducting the reaction to assure that extensive
decomposition does not occur after the dehydration reaction has been
brought about, thus the proportion of concentrated sulfuric acid in a
solvent must be adjusted so that extensive decomposition does not
prevail. It is relatively easily determined just what the best
conditions for the use of a specinc reagent are. In general, we prefer
to use temperatures of not greater than about 50 C., although
appreciably lower temperatures are often advisable with the more
sensitive compounds and with more destructive acids. In some cases it
is possible to use boil- ing dilute solutions of mineral acids in
water or a solvent.
The combination of acetone and anhydrous hydrogen chloride has been
found particu- larly effective in the preparation of the anhydro
compounds. The product formed may be isolated in consiste ^, good
yield, and, furthermore, there are formed novel inter- mediate
compounds. These consist of one molecule of acetone combine in a
unique manner with the anhydro compound. The acetone derivatives are
forms in which the anhydro compounds may be most readily isolated in a
high state of purity, often in crystalline form, and they are readily
converted to the free anhydro compounds by treatment with aqueous
acid. It is often advisable to concentrate the reaction mixture
preferably at moderate temperature under a vacuum after completion of
the reaction. In this way the crystalline acetone derivative is
generally obtained direcdy from the concentrated reaction mixture.
Other acids than hydrogen chloride may be used in acetone to form the
anhydro compounds as their acetone derivatives, but these other acids
do not possess the advantage of high volatility permitting their ready

23. evaporation and isolation of the acetone derivatives in highly pure,
often crystalline form.
In carrying out the present process a dilute solution of the parent
compound, that is the tetracycline compound is used. By a dilute
solution is meant a concentration of 0. 1 gm. per 100 ml. of solution
or more. Concentrations of as high as about 20% and even lower than 0.
1 gm./100 ml. may be used if desired.
In general, at least one mole of acid per mole of tetracycline
compound is used. An excess of the acid over this proportion is useful
particularly if the parent compound has a basic group, that is a
dimethylamino group.
The anhydro product may often be isolated by diluting the reaction
mixture with water and neutralizing the acidic reagent. Alternatively
the acid may be neutralized and the solid separated, if insoluble in
the reaction medium. If the product is soluble, the solvent may be
removed, for example, by evaporation, to obtain the solid product. The
anhydro compounds have a limited solubility in water at pH's slightly
below the neutral range, that is between about 4 and about 7. However,
if the product does not separate from solution, the neutralized
solution may be concentrated, preferably at moderate or low
temperatures, that is not over about 50 C., to cause the product to
separate. A second method of obtaining a dry product is to freeze the
aqueous solution and dry it under vacuum.
Certain solvents may be used for extracting these products from
aqueous solution, particularly at approximately neutral pH's. These
include such polar organic solvents as water immiscible aliphatic
alcohols, for example, butanol and amyl alcohol and benzyl alcohol.
The solvent extract may then be concentrated or evaporated to dryness.
Alternatively an aqueous concentrate may be obtained by extracting the
alcohol solution with dilute acid in a small volume. The aqueous
concentrate is then adjusted to approximately neutral pH to
precipitate the product. The products may be isolated in the form of
salts with acid used for dehydration or they may be prepared from the
amphoteric compounds and a suitable strong acid (e. g. hydrochloric
acid and sulfuric acid). Furthermore, salts may be prepared from the
amphoteric compounds with strong bases such as those of alkali metals
and alcaline earth metals.
The products obtained by the process of the present invention are new
compounds.
They are solid, yellow, often crystalline materials. They may be
recrystallized from lower alcohols having from 1 to 4 carbon atoms or
from lower alcohols with water or ether.
In the following table is given the micro biological activity of
representative samples of the anhydrotetracycline type compounds whose

24. preparation and properties are described above.
Anhydrodesdi-Anhydrodesdi-Anhydro
methylamino-methylamino-diacetyl
oxytetra-chlortetra-oxytetra
cycline cycline cycline
A. aerogenes (AC 2) 12. 5 50. 0 100. 0
MT 2 12. 5 1. 56 PI 12. 5
parent 50. 0 100. 0 50. 0
E. coli 50. 0 100. 0 100. 0 Proteus 50. 0 100. 0 100. 0
Pseudomonas sp. 100. 0 100. 0 100. 0
Candida albicans 50. 0 100. 0 100. 0
Salmonella typhosa 50. 0 100. 0 100. 0 K. pneumoniae 25. 0 50. 0 100.
0
Sal. paratyphi A 25. 0 100. 0 100. 0
Sal. paratyphi B 50. 0 100. 0 100. 0
Staph. aureus 50. 0 0. 19 1. 5
Str. faecalis 50. 0 0. 19 3. 1
Brucella bronchiseptica 50. 0 0. 78 12. 5 B. subtillis 25. 0 0. 19 1.
5
Ps. aeruginosa---
Myco. ranae 12. 5 0. 39 12. 5
smegmatis 12. 5 0. 19 12. 5
phlei 12. 5 0. 19 12. 5
No. 607 12. 5 0. 19 12. 5
berolinense 12. 5 0. 78 PI 25. 0
butyricum 12. 5 0. 78 PI 12. 5
The following examples are given by way of illustration only and are
not to be considered as limitations on the scope of this invention,
which is to be limited by the appended claims only.
EXAMPLE I.
Anhydrodesdimethylaminochlortetracycline -One and one-half grams of
pure desdimethylaminochlortetracycline in 60 ml. of 50%
dioxane-methanol was treated with 60 ml. of saturated methanolic
hydrogen chloride solution, carefully filtered, then left overnight in
the refrigerator. Long orange needles of
anhydrodesdimethylaminochlortetracycline separated in an analytically
pure state. This material decomposed without liquefaction at about 240
C. For analysis it was dried at 100 C. in vacuo.
Anal. calcd. for CoHI6NO, C1 : C, 57. 49 ;
H, 3. 85 ; N, 3. 35 ; Cl, 8. 49 ; m. w. 418. Found :
C, 57. 13 ; H, 4. 04 ; N, 3. 17 ; Cl, 8. 70, m. w.
(titration) 421.
Anhydrodesdimethylaminochlortetracycline shows-228. 7
(dimethylformamide).

25. Its ultraviolet absorption spectrum is superimposable upon that of
anhydrochlortetracycline.
EXAMPLE II.
Anhydradesdimep. hylaminooxytetracycline-
A solution of 0. 5 g. of desdimethylaminooxy- tetracycline in 10 ml.
of methanol and 1 ml. concentrated hydrochloric acid was heated to
boiling for one minute. The heavy yellow crystalline precipitate which
formed was filtered from the cooled solution, and recrystallized from
dioxane-methanol to yield 0.4 g. pure
anhydrodesdimethylaminooxytetracycline, m. p. 232-233 (dec.).
[a.],,"=+170' (dioxane).
Anal. Calcd. for C20HltNO8 : C, 60. 15 ;
H, 4. 29 ; N, 3. 51.
Found : C, 60. 00 ; H, 4. 47 ; N, 3. 52.
The ultraviolet absorption spectrum is substantially identical to that
of anhydrooxytetracycline in either acid or alkaline ethanol solution.
EXAMPLE III.
Anhydrodesdimethylaminodesoxyoxytetracycline-Desdimethylaminodesoxyoxy
tetracyc- line (5. 0 g.) was dissolved in methanol (150 ml.). To the
stirred solution was slowly added concentrated hydrochloric acid (20
ml.) when the deep yellow solution became orange and turbid. After 45
minutes a dark precipitate had formed. The mixture set overnight at
room temperature when it was filtered. A small amount of dark red
solid collected on the filter. The filtrate was evaporated to dryness
when the residue was a bright deep yellow. It gave an amber-green with
methanolic ferric chloride and an intense red with concentrated
sulfuric acid. It was crystallized from aqueous ethanol. The
ultraviolet absorption spectrum was that of a typical anhydro
compound.
Ultraviolet absorption (methanol HC1) : peaks at 225, 267, 323, 415
mu. melting point 200-203 with decomposition.
EXAMPLE IV.
Anhydrodesdirxethylnnainotetracycline-Des- dimethylaminotetracycline
was subjected to the identical acid treatment described for
dehydration of desdimethylaminooxytetra- cycline (Example II). As in
the latter case, the product crystallized directly from the
acidmethanol reaction solvent as yellow prismatic needles in
approximately 80% yield. This material shows a biological assay of 26
oxytetracycline units per mg. against Klebsiella pneurswaiae. The
ultraviolet absorption spec- trum, which is essentially identical with
that of anhydrodestimethylaminooxytetracycline shows maxima at 270 mu
(log c2. 06) and 25 mol (log ?1.29).
EXAMPLE V.
Anhydrodiacetyloxytetracycline - Diacetyloxytetracycline (5.0 g.) was

26. dissolved in chloroform (550 ml.). Hydrogen chloride was passed
through the yellow solution for five minutes when it became slowly
orange. After standing at room temperature overnight, the solution was
evaporated to dryness when the residue was a glassy orange solid which
was crystallized as the hydrochloride from 0. 5 normal hydrochloric
acid. The product gave a greenish-amber color with methanolic ferric
chloride and an intense red color with concentrated sulfuric acid. The
ultraviolet absorption spectrum was that of a typical anhydro
compound. Analysis showed two acetyl groups present. ~
Ultraviolet absorption (methanol HC) : peaks at 229, 271, 329, 429 m .
Infrared absorption: peaks at 3.08, 3.45, 5. 75, 6. 05, 6. 17, 6. 23
mu..
Melting point 189-192 with decomposi- tion.
EXAMPLE VI.
Anhydromethomycin-In a two liter flask there was placed one liter of
reagent grade acetone, 200 g. of anhydrous potassium carbonate, 29 g.
of desdimethylaminodesoxy- oxytetracycline and 20 g. of methyl iodide.
The mixture was refluxed vigorously for 24 hours, then 70 g. of
additional methyl iodide was introduced and-reflux maintained for an
additional 48 hours. The potassium salts were filtered off and
dissolved in water. The water was extracted with ether, then acidifie
with 50% sulfuric acid. Acidification of the aqueous solution of
methomycin resulted in the rapid formation of the corresponding
anhydro compound. The yellow solid product which separated weighed
17.0 g. It was purified by crystallization from ethanol.
Anal. Calc. for CHNO, : C, 63. 47 ; H, 4. 82 ; N, 3. 53.
Found : C, 63. 68 ; H, 5. 01 ; N, 3. 78.
Melting point 233-234.
Neutra1 equivalent 203.
Ultraviolet peak EtOH-HCl A226, 268, 300 (shoulder), 327, 412 m ! l.
Infrared peau in mineral oil-2. 84, 2. 98, 3. 10, 6. 09, 6. 18, 6. 30,
6. 35, !
EXAMPLE VII.
Anhydrodesdimethylaminodesoxyoxytetracycliane-15 grams of
Desdimethylaminodesoxy- oxytetracycline was treated with a solution of
15. 2 grams of anhydrous hydrogen chloride in 600 milliliters of pure
acetone cooled to
-5~ C. and the temperature was allowed to rise to about 5~ C. until a
constant value of the optical rotation of-300'was obtained.
This takes approximately 9i hours. The solution was observe for its
ultraviolet absorption characteristics during the course of the
reaction. It was noted that the characteristic absorption spectrum of
the anhydro compound gradually appeared. After a few hours the
conversion was practically complete.

27. EXAMPLE VIII.
Samples of desdimethylaminooxytetracyc- line,
desdimethylaminochlortetracyclins, and desdimethylaminotetracycline
were individually treated as described in Example VII above with a
solution of anhydrous hydrogen chloride in acetone. After a period of
several hours at a temperature of about 5 C. each of the solutions was
concentrated under vacuum. When a small volume had been reached the
solid acetone derivatives of anhydrodesdimethylamincoxytetracycline,
anhydrodesdimethylaminochlortetracycline and
anhydrodesdimethylaminotetracycline separated as solid yellow
products. These materials were isolated and identifie by their
characteristic properties, including ultraviolet absorption spectrum.
It was found that by treatment with aqueous acid each of these acetone
derivatives was readily converted to the corresponding anhydro
compounds, that is anhydrodesdimethylaminooxytetracycline,
anhydrodesdimethylaminochlortetracycline, and
anhydrodesdimethylaminotetracycline. The identity of these compounds
was confirmed by their characteristic properties.
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* 5.8.23.4; 93p