1. * GB780058 (A)
Description: GB780058 (A) ? 1957-07-31
Process for preparing highly basic polyvalent metal salts of organic acids
Description of GB780058 (A)
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COMPLETE SPECIFICATION
Process for Preparing Highly Basic Polyvalent Metal Salts of Organic
Acids
We, N.V. DE BATAAFSCHE PETROLBUM MAATscHAPPIJ, a Company organised
under the laws of The Netherlands, of 30 Carel van
Bylandtlaan, The Hague, The Netherlands, 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:
Polyvalent metal salts, such as calcium salts, of organic acids, such
as petroleum sulphonic acids, naphthenic acids and alkyl salicylic
acids, may be used as lubricating oil additives in order to keep clean
the interior of engine cylinders, particularly cylinders of gasoline
and Diesel engines, and to prevent formation of lacquer-like or
carbonaceous products on pistons and in piston ring grooves, thus
preventing ring-sticking. Basic forms of such salts have, moreover,
the advantage of removing free acids which would have other
deleterious effects, especially corrosion. Sulphur trioxide, for
instance, is formed in the engine from the sulphur compounds present
in the motor fuel, and this combines with the water present in
combustion gases to form sulphuric acid. By using a basic salt of an
organic acid the sulphuric acid is neutralized and cannot, therefore,

2. have any further detrimental effect.
British Patent Specification No. 739,434 relates to a process for
preparing highly basic polyvalent metal salts of organic sulphonic
acids, which comprises gradually adding an alkali metal hydroxide
dissolved in water or in an aliphatic alcohol having 1 to 3 carbon
atoms or in a mixture of such an alcohol with water, to a solution of
a polyvalent metal salt of an organic sulphonic acid and an inorganic
salt of the polyvalent metal in a solvent which consists to the extent
of at least 25% by weight of an aliphatic alcohol having 1 to 3 carbon
atoms. It has now been found that this process has a wider application
than to organic sulphonic acids only. The present invention relates to
a similar process for preparing polyvalent metal salts of carboxylic
acids.
The present invention provides a process for preparing highly basic
metal salts of carboxylic acids, which comprises gradually adding an
alkali metal hydroxide dissolved in water or in an aliphatic alcohol
having 1 to 3 carbon atoms or in a mixture of such an alcohol with
water, to a solution of carboxylic acid, or a salt thereof and an
inorganic polyvalent metal salt (the polyvalent metal of the inorganic
salt being the same as that from which the salt of the carboxylic acid
is derived, if this acid is present in the form of a polyvalent metal
salt), in a solvent which consists to the extent of at least 25% by
weight of an aliphatic alcohol having 1 to 3 carbon atoms.
When applying the process according to the present invention, products
with a very high basicity can be obtained. The magni
M tude (- -1) x 100% is used hereinafter as
E a measure of the basicity, M representing the number of equivalents
of metal, and E the number of equivalents of carboxylic acid, e.g.,
per 100 grams of the basic salt. For determining the number of
equivalents of the acid, phenolic and thiophenolic or similar wealdy
acidic groups should not be included.
For example, one equivalent of alkyl salicylic acid is equal to 1 mol
of this acid.
Particularly suitable starting materials for use in the process of the
invention are carboxylic acids themselves, such as the aromatic
carboxylic acids, e.g., the alkylbenzoic acids, the aromatic hydroxy
carboxylic acids.
e.g., the alkyl-substituted hydroxybenzoic acids, such as the alkyl
salicylic acids, e.g., those with 14 to 18 carbon atoms in the alkyl
group, and the naphthenic acids, or their alkali metal, ammonium or
organic base salts or their salts with the polyvalent metals which are
required to be present in the end products. When salts are used they
are generally neutral salts but it is possible to prepare from
polyvalent metal salts of carboxylic acids which already have a

3. certain basicity, products with a considerably higher basicity.
For the sake of simplicity the solution of carboxylic acid (or salt
thereof) and inorganic polyvalent metal salt is hereinafter called the
" starting solution." Carrying out the process in solution has the
advantage that the reaction proceeds entirely in a homogeneous medium,
with the result that the reaction proceeds smoothly and a product of a
very good quality is obtained. It is frequently possible to carry out
the reaction at room temperature. A further advantage of the
homogeneous medium is that unstable hydroxides which are
insufficiently stable in the free state, may be formed and reacted in
this medium.
When the alkali metal hydroxide solution is gradually added to the
starting solution, the free hydroxide of the polyvalent metal is
formed from the inorganic polyvalent metal salt present in the said
solution, and this hydroxide combines with the carboxylic acid or salt
thereof to form the desired basic products.
The solvent used for the starting solution may, for example, be an
aliphatic alcohol having 1 to 3 carbon atoms or a mixture of such
alcohols. A mixture of an aliphatic alcohol having 1 to 3 carbon atoms
with another liquid can also be used as a solvent, provided this
mixture consists to the extent of at least 25% by weight, and, in
particular, to the extent of more than 50?O by weight, of the
aliphatic alcohol. Liquid hydrocarbons and water are particularly
suitable as this other liquid. When the alkali metal hydroxide
solution is used in the form of an aqueous solution, it is advisable
to dissolve the carboxylic acid or salt thereof and the inorganic
polyvalent metal salt in a solvent containing at least such a quantity
of the ali- phatic alcohol having 1 to 3 carbon atoms that the
solution, after addition of the aque- ous alkali metal hydroxide
solution, still contains at least 25 , by weight of the said aliphatic
alcohol, calculated on the solvent phase.
The desired conversion is promoted when the nature and the proportion
of the various components of the mixture to be converted are so chosen
that the alkali metal salt formed during the conversion, e.g., sodium
chloride, precipitates from the solution.
The preparation of the starting solution may be carried out by adding
a solution of the inorganic polyvalent metal salt to a solution of a
carboxylic acid or salt thereof, or by dissolving the inorganic
polyvalent metal salt, as such, in a solution of the carboxylic acid
or salt thereof.
According to a particular embodiment of the process of the invention,
a polyvalent metal salt of the carboxylic acid is formed in the
solvent to be used by converting the free carboxylic acid or an alkali
metal, ammonium or organic base salt thereof in the said solvent with

4. an excess of inorganic polyvalent metal salt. If the alkali metal
hydroxide solution is then added gradually in quantities corresponding
to the excess of inorganic salt used, the salt which is originally
formed from the carboxylic acid and the polyvalent metal is further
converted to a basic product.
The invention is particularly important for the preparation of highly
basic salts, e.g., alkylsalicylates, of bivalent metals, particularly
of the alkaline earth metals and zinc.
However, highly basic salts of metals of higher valency, e.g.,
aluminium or chromium, may also be prepared by the process of the
invention.
Inorganic polyvalent metal salts which are especially suitable are the
polyvalent metal chlorides and bromides. Other inorganic polyvalent
metal salts. such as the nitrates, may, however, be used.
The alkali metal hydroxide may be dissolved in the same alcohol as is
present in the starting solution. It is also possible, however, to use
the alkali metal hydroxide in the form of a solution in another
aliphatic alcohol having 1 to 3 carbon atoms. The alkali metal
hydroxide may also be dissolved in water or in a mixture of water and
one or more aliphatic alcohols having 1 to 3 carbon atoms. In many
cases a solution of sodium or potassium hydroxide in methanol or
ethanol, either of which may be diluted in water, is very suitable.
The alkali metal hydroxide solution should be added gradually to the
starting solution so as to prevent a local excess of the free
hydroxide of the polyvalent metal being formed and separating out from
the solution as such instead of combining with the carboxylic acid or
salt thereof to form the desired highly basic salt. In general a
satisfactory yield of highly basic salt may be obtained by adding the
alkali metal hydroxide solution to the starting solution over a period
of from 1 minute to 1 hour.
In order to prevent a local excess of the hydroxide of the polyvalent
metal being formed when adding the alkali metal hydroxide solution to
the starting solution, it is also advisable to mix the alkali metal
hydroxide solution as quickly as possible uniformly with the starting
solution. For this purpose the supply of the alkali metal hydroxide
solution may be spread over different parts in the space in which the
conversion occurs.
The process may be carried out either con tinuously or batchwise. When
carrying out the process continuously a part of the solution which
runs off at the end of the reaction space may be recycled. This has
the advantage that the alkali metal hydroxide solution can be supplied
more slowly than when the conversion is carried out without recycling.
Suitable starting solutions for use in the present process are
solutions which contain the carboxylic acid or salt thereof in a

5. concentration of 1% to 10% by weight and the inorganic polyvalent
metal salt in an excess with respect to the carboxylic acid or salt.
0.5 to 5 normal solutions of the alkali metal hydroxide are suitable.
If desired, however, solutions of other concentrations may also be
used.
Isopropanol is especially suitable as the aliphatic alcohol which is
used for dissolving the carboxylic acid or salt thereof and the
inorganic polyvalent metal salt. However, other aliphatic alcohols
having 1 to 3 carbon atoms, such as methanol and ethanol, may also be
used.
Light hydrocarbon oils, particularly hydrocarbons with 10 or less
carbon atoms or mixtures thereof, are especially suitable as the
liquid hydrocarbon with which the said alcohols may be mixed. The
hydrocarbons may be paraffinic, naphthenic or aromatic or they may be
hydrocarbons of a mixed type. Examples of suitable hydrocarbons are
toluene and gasoline, such as gasoline having a boiling range of 60
C.-80 C. Mixtures of such hydrocarbons with alcohols containing up to
70% by weight of hydrocarbons are suitable for use in the process of
the invention.
In general the basic product formed during the conversion is
considerably less soluble in the solvents used than the starting
material or even almost insoluble therein, so that the basic salt
separates out from the solution. This is also the case with that part
of the hydroxide of the polyvalent metal which is formed and which
does not combine with the starting carboxylic acid or salt thereof, as
also with the alkali metal salt formed during the conversion, e.g.,
sodium chloride. On the other hand, the unconverted carboxylic acid or
salt thereof remains in the solution.
At the end of the conversion the solution and the components which
have precipitated from the solution are separated from each other,
e.g., by filtering or centrifuging.
From the insoluble components the basic product is then extracted. In
general light hydrocarbon oils are suitable for this purpose,
particularly hydrocarbon oils having an end boiling point not higher
than 300"C.
The hydrocarbon oil may be aliphatic naphthenic or aromatic or of the
mixed type. Hydrocarbons with 10 or less carbon atoms or mixtures
thereof are particularly suitable. Examples of suitable hydrocarbons
are benzene, heptane and gasoline, such as gasoline with a boiling
range of 60 C.-80 C.
If desired, the extracts obtained may, moreover, be concentrated by
evaporating the solvent used for the extraction.
The solution obtained at the end of the conversion, which solution
also contains a quantity of the neutral salt, may again be subjected

6. to the process according to the invention in order to obtain a further
quantity of the highly basic product.
Alternatively, the reaction mixture obtained at the end of the
conversion can be freed from solvent by distilling the latter off and
the residue can then be extracted with a light hydrocarbon oil.
Finally the basic salt obtained in the extraction may be mixed with
lubricating oil. In this case a solution is obtained which still
contains neutral salicylate and which will therefore have a lower
basicity.
The process of the invention may be carried out at ordinary or
elevated temperature.
Elevated temperatures are particularly suitable when using
concentrated solutions which are often highly viscous at ordinary
temperature. Naturally, the temperatures used will generally not be
higher than the initial boiling point at normal pressure of the
solvent.
Highly basic salts prepared by the present process may be incorporated
in minor proportions in oleaginous fluids to provide valuable
oleaginous compositions, such as lubricating oil and fuel oil
compositions.
The highly basic salts prepared by the present process may be used in
lubricating oils in widely varying concentrations, but in general the
concentrations used will vary between 0.1% and 15% by weight. If
desired, the said highly basic salts may be combined with other
additives, e.g., anti-oxidants and extreme pressure dopes.
The highly basic salts prepared by the present process may also be
used in other hydrocarbon oils. For example, they are suitable for use
in fuel oils where they counteract clogging of lines, filters and the
like, and corrosion. They can also be added to light hydrocarbon
mixtures, such as those used as anti-corrosives. On account of their
surface-active properties the highly basic salts may also be used in
preparing emulsions of water and oil. They may also be used in the
preparation of lubricating greases.
The invention is illustrated by the following examples in which the
parts are parts by weight.
EXAMPLE I
250 Parts of the sodium salt of ortho-sec.
cetyl-salicylic acid with a molecular weight of 374 (theoretical 384)
were dissolved in 450 parts of liquid consisting of 350 parts of
isopropanol, 50 parts of ethanol (96%) and 50 parts of benzene.
Calcium chloride was also subsequently dissolved in a ratio of 3.5
mol.
per mol of sodium alkyl salicylate in the mixture obtained. At room
temperature, while stirring, 6 mol of potassium hydroxide per mol of

7. sodium alkyl salicylate, dissolved in 360 parts of the same liquid
mixture used as solvent for the sodium alkyl salicylate, were
gradually added to the solution over a period of 30 minutes. After the
whole quantity of potassium hydroxide had been added, the reaction
mixture was centrifuged (centrifugal force approximately 1200 times
the force of gravity), the solid substance formed being separated in a
gel-like form. This substance was taken up in 500 parts of gasoline
with a boiling range of 60OC.-80 C., in which the desired calcium salt
dissolved, the potassium chloride and calcium hydroxide also formed in
the reaction remaining behind in the form of insoluble crystals which
were removed by centrifuging. Finally, the gasoline and remaining
organic liquid were distilled off from the clear solutions, As residue
were obtained 152 parts of solid substance which contained 34 ', of
the original alkyl salicylic acid and had a calcium content of 6.78
equivalents of calcium per equivalent of alkyl salicylic acid. The
basicity of the product.
which was soluble in mineral oil, was therefore 578.
EXAntPLE II
7.5 Parts by weight of technical carboxylate consisting of 37 ' by
weight of sodium alkyl salicylates, 11 by weight of sodium alkyl
phenolates, 185' by weight of a mixture of alkyl phenols and alkene
polymers and 34 ,b by weight of xylene were used as the starting
material. In the preparation of this mixture an alkene mixture, the
components of which contain 14 to 18 carbon atoms in the molecule, was
used as alkylation agent.
The alkyl groups in question thus also contain amounts of carbon atoms
varying from 14 to 18. The starting material was freed from xylene by
distillation and then dissolved in 150 parts by weight of a mixture of
85% by weight of isopropanol and 15 ', by weight of benzene. To this
solution 2.5 mol of calcium chloride per mol of alkyl salicylic acid
were added in the form of a solution of 3 by weight of calcium
chloride containing two molecules of water of crystallization in a
mixture of isopropanol and benzene as referred to above.
At room temperature, while stirring, 4 mol of potassium hydroxide per
mol of alkyl salicylic acid were gradually added to this mixture in
the form of a 0.50 normal solution in a mixture of 90 '' by weight of
the above isopropanollbenzene mixture and
10 ' by weight of ethanol.
The reaction mixture was centrifuged (centrifugal force approximately
1200 times the force of gravity) and the sediment obtained taken up in
gasoline with a boiling range of 60-C. to 80 C, after which the
inorganic salts were rs!noved by centrifuging and the basic product
was obtained in dissolved form. After removing the solvent by
distillation, there were obtained 2.23 parts by weight of a solid

8. residue containing 75 ? of the alkyl salicvlic acids from the starting
material together with 5.16 equivalents of calcium per equivalent of
alkyl salicylic acid.
The basicity of the product was therefore 416 - .
EXAMPLE III
2 Parts by weight of the sodium salt of secondary cetyl benzoic acid
were dissolved in 40 parts by weight of a mixture of 85 by weight of
isopropanol and 15' by weight of benzene. To this solution 2.5 mol of
calcium chloride per mol of cetyl benzoic acid were added in the form
of a solution of 30: by weight of calcium chloride containing two
molecules of water of crystallization in a mixture of isopropanol and
benzene as referred to above.
At room temperature. while stirring. 4 mol of potassium hydroxide per
mol of benzoic acid were gradually added to this mixture in the form
of a 0.50 normal solution in a mix- ture of 90 ' by weigllt of the
said mixture of isopropanol and benzene and 106 by weight of ethanol.
The reaction mixture was centrifuged (centrifugal force approximately
1200 times the force of gravity) and the sediment obtained taken up in
gasoline with a boiling range of 60'C. to 90-C.. after which the
inorganic salts ',vere removed by centrifuging and the basic product
was obtained in dissolved form. After removing the solvent, there were
obtained 1.86 parts by weight of a solid residue containing 61 of the
original cetyl benzoic acid and 5.88 equivalents of calcium per
equivalent of cetyl benzoic acid. The product had a basicity of 488
,h.
What we claim is:
1. A process for preparing highly basic polyvalent metal salts of
carboxylic acids.
which comprises gradually adding an alkali metal hydroxide dissolved
in water or in an aliphatic alcohol having 1 to 3 carbon atoms or in a
mixture of such an alcohol with water, to a solution of carboxylic
acid or a salt thereof and an inorganic polyvalent metal salt (the
polyvalent metal of the inorganic salt being the same as that from
which the salt of the carboxylic acid is derived. if this acid is
present in the form of a polyvalent metal salt). in a solvent which
consists to the extent of at least ~ by weight of an aliphatic alcohol
having 1 to 3 carbon atoms.
2. A process as claimed in Claim 1, wherein the solution of a salt of
the carboxylic acid and a polyvalent metal is produced by converting
the free carboxylic acid or an alkali metal, ammonium or organic base
salt thereof in the said solvent with an excess of the