Condensation reaction carboxylic acid

A condensation reaction joins two molecules and splits out a small molecule. The small molecule is usually water. The formation of a peptide bond is an example of a condensation reaction. The conditions necessary for a condensation reaction vary with the functional groups involved. In most cases, a catalyst will be present. The two most common catalysts are acids and enzymes. Two alcohols will condense to form an ether. A carboxylic acid condenses with an alcohol to form an ester. A carboxylic acid condenses with an amine to form an amide. 

The workhorse of the VLSI industry today is a composite novolac-diazonaphthoquinone photoresist that evolved from similar materials developed for the manufacture of photoplates used in the printing industry in the early 1900 s (23). The novolac matrix resin is a condensation polymer of a substituted phenol and formaldehyde that is rendered insoluble in aqueous base through addition of 10-20 wt% of a diazonaphthoquinone photoactive dissolution inhibitor (PAC). Upon irradiation, the PAC undergoes a Wolff rearrangement followed by hydrolysis to afford a base-soluble indene carboxylic acid. This reaction renders the exposed regions of the composite films soluble in aqueous base, and allows image formation. A schematic representation of the chemistry of this solution inhibition resist is shown in Figure 6. 

Condensation reactions have appeared several times outside the context of polymer synthesis. For example, two molecules of H2SO4 condense to form disulfuric acid (H2S2O7), and a carboxylic acid condenses with an alcohol to form an ester (see Section 7.6). 

Modification of the protein amine groups is the procedure most frequently used to produce antibody-liposome conjugates. Early procedures used crosslinking agents, such as l-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (27,28) in the presence of preformed liposomes containing a lipophilic carboxylic acid. Condensing agents like these tend to form protein-protein polymers. Control of these reactions is typically difficult and complex, and as a result separation of the liposomes from protein polymers is a... 

An even simpler route to the fused-ring 1,3-dithiolium salts is by condensation of 203 with aromatic and even aliphatic carboxylic acids. The reaction, which is generally carried out in phosphorus oxychloride, proceeds rapidly and always in good yield. The parent member of this series of benzo-l,3-dithiolium salts is obtained in 80-90% yield when the acid used is formic acid (Table... 

As a source of HCHO, formalin, a 37 percent aqueous solution of HCHO stabilized with 12 to 15 percent of methanol, is the most popular. Besides formalin, paraformaldehyde [(HCHO) ] and trioxane [(HCHO)3] are also used. When methanol is added in the feed or when methylal [CH2(OCH3)2] or hemiformal [CH3OCH2 OH] is used as the source of HCHO, a mixture of carboxylic acids and esters is obtained because both the esterification of carboxylic acid and the hydrolysis of ester are much more rapid than the condensation reaction. The reaction is usually performed in the presence of an excess of carboxylic acid with respect to the amount of HCHO the carboxylic acid/HCHO molar ratio is 1.3 to 20 because HCHO is generally more susceptible to degradation than carboxylic acids. The reaction temperature is in the range of 250 to 400 °C. 

Acylation can be effected by direct esterification with carboxylic acids. The reaction is performed with activating agents and a base, with A,A-dicyclohexylcarbodii-mide (DCC) serving as a powerful condensation agent. The homogeneous-phase... 

The 1,2-diketone 1 can be converted into the salt of an a-hydroxy carboxylic acid upon reaction with alkali hydroxide, which upon acidic workup affords a-hydroxy carboxylic acid 2. Semi-aromatic diketones, aliphatic, heterocyclic and aromatic diketonesundergo this rearrangement. The substituents should not bear hydrogens a to the carbonyl group, to avoid competing reactions such as aldol condensation. 

The aldehydes can be the desired product but often they are reduced to the alcohol or oxidized to the carboxylic acid. Other reactions, such as aldol condensations, can be employed as illustrated with butanal. Reduction of the aldol product gives the commodity chemical, 2-ethylhexanol, used to make plasticizers such as dioctyl phthalate (dioctyl phthalate is the common name for the diester of phthalic acid with 2-ethylhexanol, but more precisely, it can be called di-2-ethylhexyl phthalate). 

Esters are commonly synthesized from carboxylic acids by reaction of the acid with an excess of alcohol containing a catalytic amount of a mineral acid. In cases where practical considerations dictate it, the acid can be converted to an acyl halide (usually the chloride) and then condensed with the appropriate alcohol. A less commonly used procedure involves direct alkylation of the carboxylate ion with an alkyl halide. Even when this latter procedure (Eq. 6.1) involves a silver carboxylate and alkyl chloride, the reaction is of marginal practical value. 

Compounds 81 are synthesized by the Ugi reaction, which is a multicomponent process involving o-fluoroaniline, aldehyde, isocyanide, and IH-imidazole-5-carboxylic acid. The reaction is initiated by condensation of aniline with aldehyde leading to the corresponding imine, which successively reacts with the acid and isocyanide to give target compounds 81. Trifluoroethanol is used as a solvent in this reaction (Scheme 4.38) (Spatz et al. 2007). 

Other Condensation Reactions. BF3-MeOH and BF3-OEt2 with ethanol are widely used in the esterification of various kinds of aliphatic, aromatic, and carboxylic acids the reaction is mild, and no rearrangement of double bonds occurs. This esterification is used routinely for stable acids prior to GLC analysis. Heterocyclic carboxylic acids, unsaturated organic acids, biphenyl-4,4 -dicarboxylic acid, 4-aminobenzoic acid, and the very sensitive 1,4-dihydrobenzoic acid are esterified directly. 

This is an example of the Doebner synthesis of quinoline-4-carboxylic acids (cinchoninic acids) the reaction consists in the condensation of an aromatic amine with pyruvic acid and an aldehj de. The mechanism is probably similar to that given for the Doebner-Miller sj nthesis of quinaldiiie (Section V,2), involving the intermediate formation of a dihydroquinoline derivative, which is subsequently dehydrogenated by the Schiff s base derived from the aromatic amine and aldehyde. 

A classical way to achieve regioselectivity in an (a -i- d -reaction is to start with a-carbanions of carboxylic acid derivatives and electrophilic ketones. Most successful are condensations with 1,3-dicarbonyl carbanions, e.g. with malonic acid derivatives, since they can be produced at low pH, where ketones do not enolize. Succinic acid derivatives can also be de-protonated and added to ketones (Stobbe condensation). In the first example given below a Dieckmann condensation on a nitrile follows a Stobbe condensation, and selectivity is dictated by the tricyclic educt neither the nitrile group nor the ketone is enolizable (W.S. Johnson, 1945, 1947). 

In his cephalosporin synthesis methyl levulinate was condensed with cysteine in acidic medium to give a bicyclic thiazolidine. One may rationalize the regioselective formation of this bicycle with the assumption that in the acidic reaction mixture the tMoI group is the only nucleophile present, which can add to the ketone. Intramolecular amide formation from the methyl ester and acid-catalyzed dehydration would then lead to the thiazolidine and y-lactam rings. The stereochemistry at the carboxylic acid a-... 

Maleic anhydride condenses with 2-aminothiazole-4-carboxylic acid giving the raaleimide 107 (269) another report claims, however, that the reaction of 2-amino-4-methylthiazole with this anhydride gives the N-substituted maleamic acid (108) (Scheme 73) (270). 

Thiazolecarboxaldehydes in the presence of a strong base (103) give equal amounts of the corresponding alcohol and carboxylic acid (Canniz-aro reaction). In the presence of potassium cyanide thiazolecarboxalde-hyde undergoes the benzoin condensation (104, 105),... 

Condensa.tlon, A variety of condensation reactions involving the hydroxyl or the carboxyl or both groups occur with lactic acid. The important reactions where products can be obtained ia high yields are esterificatioa (both iatramolecular and with another alcohol or acid), dehydration, and aminolysis. 

Branched-Chain Carboxylic Acids. Branched-chain acids such as 2-methylbutyric, 3-methylbutyric, isooctanoic, and isononanoic acids are produced by the oxo reaction, giving first the corresponding aldehyde, which is then oxidized to the acid. 2-EthyIhexanoic acid is produced by the aldol route from butyaldehyde in three steps aldol condensation hydrogenation of the carbon—carbon double bond and oxidation of the branched-chain saturated aldehyde to 2-ethyIhexanoic acid (see Carboxylic Acids, branched-chain acids). 

Neo acids are prepared from selected olefins using carbon monoxide and acid catalyst (4) (see Carboxylic Acids, trialkylacetic acids). 2-EthyIhexanoic acid is manufactured by an aldol condensation of butyraldehyde followed by an oxidation of the resulting aldehyde (5). Isopalmitic acid [4669-02-7] is probably made by an aldol reaction of octanal. 

The dimer acids [61788-89-4] 9- and 10-carboxystearic acids, and C-21 dicarboxylic acids are products resulting from three different reactions of C-18 unsaturated fatty acids. These reactions are, respectively, self-condensation, reaction with carbon monoxide followed by oxidation of the resulting 9- or 10-formylstearic acid (or, alternatively, by hydrocarboxylation of the unsaturated fatty acid), and Diels-Alder reaction with acryUc acid. The starting materials for these reactions have been almost exclusively tall oil fatty acids or, to a lesser degree, oleic acid, although other unsaturated fatty acid feedstocks can be used (see Carboxylic acids. Fatty acids from tall oil Tall oil). 

Chromone-2-carbaldehyde, 3-methyl-synthesis, 3, 709 Chromonecarbaldehydes Knoevenagel condensation, 3, 711 Chromone-3-carbaldehydes mass spectra, 3, 615 oxidation, 3, 709 reactions, 3, 712 Schiff bases, 3, 712 synthesis, 3, 821 Chromone-2-carbonyl chloride Grignard reaction, 3, 711 Chromonecarboxamide, N-tetrazolyl-antiallergic activity, 3, 707 Chromone-2-carboxylic acid, 3-chloro-ethyl ester... 

Claisen condensation, 6, 156 reactions, S, 92 IsothiazoIe-3-carboxyIic acids decarboxylation, 6, 156 Isothiazole-4-carboxylic acids decarboxylation, 6, 156 Isothiazole-5-carboxylic acids decarboxylation, S, 92 6, 156 IR spectroscopy, 6, 142 Isothiazole-3-diazonium borofluoride decomposition, 6, 158 IsothiazoIe-4-diazonium chloride, 3-methyl-reactions with thiourea, 6, 158 Isothiazole-5-diazonium chloride, 4-bromo-3-methyl-halogen exchange, 6, 163 Isothiazole-5-diazonium chloride, 3-methyl-reactions... 

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