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1. 1
Research
Aromatic CARBOXYLIC ACIDS
 Introduction
The chemical change of the carboxylic corrosive useful bunch into the comparing carboxylic
amide (peptide) may be a exceptionally imperative response in bioorganic chemistry.1 The
amide bond has long pulled in much intrigued since it is an critical building unit in proteins.
The tall solidness of the amide linkage towards hydrolysis is of vital noteworthiness to
organic frameworks, since it permits the development of peptides from moderately
straightforward amino acid precursors.2 Too amides and polyamides play an awfully vital
part within the development of macromolecular science and the polymer industry.3 Amides
have been arranged by a number of methods counting the response of amines with carboxylic
acids, the condensation of amino acids, ring opening response of lactams, by oxidation of
fragrant aldehydes,4 from actuated alcohols utilizing manganese (IV) dioxide in a couple
oxidation process,5 from O-sulfonyloximes and Grignard reagents.6 Isocyanates are
profoundly unsaturated natural compounds.
They respond promptly with numerous differing compounds containing dynamic protons such
as alcohols, amines and carboxylic acids. The amalgamation of amides by the response of a
carboxylic corrosive with an isocyanate has gotten small attention.1 One of the points of
interest of the isocyanation strategy for planning amides lies within the good solubility of
isocyanates within the response media compared to amines. In any case, classical strategies
for the amalgamation of amides regularly have restrictions and are not ecologically friendly.
The utilize of ecologically generous response media is exceptionally critical in see of
today's ecologically mindful position. In association with this, liquid salts7 and room
temperature ionic fluids (RTILs)8 have gotten a extraordinary bargain of intrigued over the
past decade as novel dissolvable frameworks for natural and inorganic transformations.
ILs are low temperature salts which represent a brand new class of non-molecular, ionic
solvents. Fascinating features of those liquids are their ability to solvate a broad range of
both inorganic and organic materials, low force per unit area, recyclability, high thermal
stability and easy handling.9 additionally, another interesting aspect is that the possibility
to change their physical and chemical properties by varying their structures with esteem to
the selection of organic cations and anions, and side-chains attached to the organic cation.
Thus, ILs are described as 'designer solvents'. All of those properties make these systems
superb candidates to be used in developing environmentally benign chemical processes, and

2. 2
really, nowadays, ILs are extensively diffused as greener alternatives to classical volatile
organic solvents in chemical transformations.9 Particularly ILs supported 1,3-
dialkylimidazolium cation are extensively applied for organic and inorganic synthesis.
Moreover, ILs are straightforward as they're easily prepared and straightforward to
recycle.10 in sight of the emerging importance of imidazolium and ammonium based ILs as
novel reaction media, we wish to analyze the applying of ILs as promoters and green solvent
systems for the synthesis of amides under mild conditions.
 General manner for amidation
0.4 g of dry IL (IL was dried beneath vacuum at 70ºC for four h) was once brought to the
carboxylic acid (1 mmol) and heated with stirring for 10 min till the acid used to be
dissolved. Then isocyanate (1 mmol) was added under nitrogen atmosphere, and the
combination was once stirred for the required quantity of time (Table 2). At the cease of
reaction time (monitored by using TLC), the mixture was once precipitated in water,
filtered off, dried and recrystallized to provide the corresponding benzamide derivative.
A pyrex response flask which
was once charged with
tetrabutylammonium bromide
(TBAB) (0.4 g) and benzoic acid (1
mmol) was heated at 90ºC. Then the
phenyl isocyanate (1 mmol) used to
be delivered to the stirred molten
combination under nitrogen
atmosphere, and the mixture was
stirred for a period of time (Table 2).
At the stop of response time
(monitored by way of TLC), the

3. 3
combination was once precipitated in water, filtered off, dried and the white stable was
once recrystallized from a mixture of ethanol/water (80/20) to furnish benzanilide.
(c) A mixture of NMP (0.5 ml) and benzoic acid (1 mmol) in a round-bottom flask was
once heated at 100ºC. Phenyl isocyanate (1 mmol) was once introduced to this combination
below nitrogen atmosphere, and the combination was once stirred for a duration of time
(Table 1). After completion of the reaction (checked with the aid of TLC), the combination
was once precipitated in water, filtered off, dried and the white strong was once
recrystallized from a combination of ethanol/water (80/20) to provide benzanilide.
 Results and Discussion
In order to get perception of the function of ILs as inexperienced and non-volatile
solvents in contrast to the traditional organic solvents for the reactions of fragrant
carboxylic acids with isocyanates, first the response of phenyl isocyanates with
benzoic acid was performed in distinct conventional natural solvents such as toluene,
N,N-dimethylformamide (DMF) and N-methylpyrrolidinone (NMP). When toluene and
DMF had been used as solvents, the response did now not proceed efficiently and by-
products have been observed by using TLC technology. By using NMP as solvent the
response did now not show any by-products, however the reasonable yields of the
preferred product indicate that this solvent is now not very suitable for this kind of
response .
Then, the amidation response was carried out in ILs as solvents. First we studied the response
of benzoic acid and phenyl isocyanate in details. The effect of unique kinds of ILs on the
yields of this reaction was also investigated (Scheme 1, Table 2). The high-quality result was
bought with 1,3-diallylimidazolium bromide (entry 9) and this IL used to be selected for the
different reactions.
The system was once efficiently tested
through the reactions of numerous aromatic

4. 4
carboxylic acids with aromatic as well as aliphatic isocyanates in the presence of 1,3-
diallylimidazolium bromide as IL (Scheme 2, Table 3). It is very fascinating to point out that
while fragrant isocyanates in traditional solvents do now not provide exact yields of
corresponding amides, we bought super yields of the corresponding amides in ILs barring any
formation of side merchandise.
 General Properties
Some significant models are benzoic acid(C6H5•CO2H) and the isomeric toluic acids (o-, m-
and p -
CH3•C6H4•CO2H); phenylacetic
acid(C6H5•CH2•CO2H); the unsaturated corrosive cinnamic corrosive (C6H5•CH = •CO2H);
the subbed acidssalicylic corrosive (o-HO•C6H4•CO2H) and anthranilic corrosive (o-
H2N•C6H4•CO2H); and the benzenedicarboxylic acids phthalic corrosive (o-C6H4(CO2H)2)
andterephthalic corrosive (p-C6H4(CO2H)2). A large portion of these are mixes of extensive
business significance.
Those properties and responses of sweet-smelling carboxylic acids which are because of the
nearness of the carboxyl gathering are much of the time just imperceptibly not the same as
those of the aliphatic analogs, in any event, when the gathering is legitimately connected to
the sweet-smelling core.
Acridity OF AROMATIC CARBOXYLIC ACIDS

5. 5
Benzoic corrosive (p Ka4•20) is a somewhat more grounded corrosive than acidic corrosive
(pKa4•76). This must be to a great extent credited to the more prominent electronegativity
of thesp2-hybridized ring carbon molecule, since acrylic corrosive (CH2= •CO2H; pKa4•25)
has a tantamount acridity. The impact of meta-or para-substituents on the acridity of subbed
acids (see Table 3) might be justified as far as the way where the substituents can alter the
electronegativity of this ring carbon molecule by either inductive or mesomeric impacts.
The Acidity of numerous ortho subbed benzoic acidsis more prominent than would be normal
exclusively based on the electronic impacts of the ortho substituents, which accordingly
should apply an extra balancing out impact on the carboxylate particle. This emerges on
account of salicylic corrosive (pKa 2.98), for instance, as the consequence of inward hydrogen
holding.
The
electrochemical decrease of fragrant carboxylic acids might be utilized to get ready
aldehydes, essential alcohols, methyl arenes or dihydroarene carboxylic acids, contingent
upon the substrate and response conditions employed.2,4,5 Primary liquor arrangement is
seen when sweet-smelling carboxylic acids are diminished in unequivocally acidic media
utilizing cathode material of high hydrogen over-potential (regularly mercury or lead)
Simultaneous Formation of Ester and Amide Bonds
Fragrant carboxylic acids respond with sweet-smelling NH2and OH bunches at a similar rate
within the sight of mixes, for example, diphenyl chlorophosphate (DCP)60 or tosyl
chloride.61,62 This outcomes in the arrangement of high atomic weight copoly(ester amides).
In this way the copolycondensation of p-aminobenzoic and p-hydroxybenzoic acids gives
dissolvable poly(ester amide)s60 with a measurable dispersion of ester and amide capacities.
Similarly the copolycondensation of diacids with diphenols and diamines gives
statisticalcopolymers. Anyway for this situation amide and ester linkages are straight on
and tail to tail and not go to tail as in the result of reaction.
 Aromatic acids

6. 6
Sweet- smelling acids
incorporate intensifies that
contain a COOH bunch clung to a
fragrant ring. The least complex
sweet-smelling corrosive is benzoic
corrosive.
Sweet- smelling carboxylic
acids show not just the
corrosiveness and different responses expected of carboxylic acids (as a corrosive, benzoic
corrosive is marginally more grounded than acidic corrosive) in any case, like other fragrant
mixes, additionally experience electrophilic substitutionreactions. The COOH bunch is
deactivating, which means electrophilic replacements happen less promptly than with
benzene itself (Friedel-Crafts responses don't happen), and meta-coordinating, implying
that the approaching substance will enter at a position meta to the COOH gathering, instead
of at an ortho or para position, as in, for instance, the nitration of benzoic acid.

7. 7
Benzoic corrosive, a strong at room temperature (dissolving point 122 °C [252 °F]), was to
begin with portrayed in 1560, having been arranged by refining gum benzoin, a resinobtained
from certain Asian trees. It happens in different plants, both in free corrosive frame and in
ester shape. It is additionally a constituent of the pee of certain creatures, particularly
steeds, as an amide of glycine called heppuric acid, C6H5CONHCH2COOH. The sodium salt,
sodium benzoate, is utilized as a additive in numerous foods. Some other critical fragrant
acids incorporate the following:
Salicylic acid is both a carboxylic acid and a phenol, so it can be esterified in two ways, with
both giving rise to familiar products. In methyl salicylate (oil ofwintergreen), the COOH
group of salicylic acid is esterified with methanol(CH3OH), whereas in acetylsalicylic acid
(aspirin) the acid component of the ester is acetic acid, and salicylic acid contributes the
phenolic ―
OH group.
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