Acids, aromatic preparation

AROMATIC ACID CHLORIDES The chlorides of aromatic acids are prepared —... 

Formation of carboxylic acids ami their derivatives. Aryl and alkenyl halides undergo Pd-catalyzed carbonylation under mild conditions, offering useful synthetic methods for carbonyl compounds. The facile CO insertion into aryl- or alkenylpalladium complexes, followed by the nucleophilic attack of alcohol or water affords esters or carboxylic acids. Aromatic and a,/ -unsaturated carboxylic acids or esters are prepared by the carbonylation of aryl and alkenyl halides in water or alcohols[30l-305]. 

Formation of AllylEsters. AEyl esters are formed by reaction of aEyl chloride with sodium salts of appropriate acids under conditions of controEed pH. Esters of the lower alkanoic, alkenoic, alkanedioic, cycloalkanoic, benzenecarboxyEc, alkylbenzene carboxyEc, and aromatic dicarboxyEc acids maybe prepared in this manner (25). More information can be found about the reactivity of aEyl compounds (see Allyl alcohol and mono allyl derivatives). 

Because of the structural requirements of the bielectrophile, fully aromatized heterocycles are usually not readily available by this procedure. The dithiocarbamate (159) reacted with oxalyl chloride to give the substituted thiazolidine-4,5-dione (160) (see Chapter 4.19), and the same reagent reacted with iV-alkylbenzamidine (161) at 100-140 °C to give the 1 -alkyl-2-phenylimidazole-4,5-dione (162) (see Chapter 4.08). Iminochlorides of oxalic acid also react with iV,iV-disubstituted thioureas in this case the 2-dialkylaminothiazolidine-2,4-dione bis-imides are obtained. Thiobenzamide generally forms linear adducts, but 2-thiazolines will form under suitable conditions (70TL3781). Phenyliminooxalic acid dichloride, prepared from oxalic acid, phosphorus pentachloride and aniline in benzene, likewise yielded thiazolidine derivatives on reaction with thioureas (71KGS471). 

AROMATIC CARBOXYLIC ACIDS Aromatic carboxylic acids may be prepared —... 

Secondary amines containing at least one aromatic group are readily nitro-sated in an aqueous medium using sodium nitrite and hydrochloric acid. The preparation of IV-nitrosophenylglycine, an intermediate in the preparation of 3-phenylsydnone [24, 25], is a case in point. 

Modern polyimides are most likely an outgrowth of trying to find increased utilization of aromatic polycarboxylic acids as prepared by oxidation of poly-methylbenzenes, a major component in petroleum feedstocks. Therefore, it is not too surprising that the first commercial application of these materials appeared... 

Carboxylic acids are prepared by at least four methods (1) by oxidation of primary alcohols or aldehydes, (2) by oxidation of an aromatic side chain, (3) from a Grignard reagent and carbon dioxide, or (4) by hydrolysis of a nitrile, RC=N. 

By means of this method, o-nitrophenylarsonic acid was prepared in a yield of 86% as compared with a yield of only 60% by the original Bart process. According to Schmidt, the proportion of by-products, especially the parent hydrocarbon (benzene in the illustration), increases with higher alkalinity. In acid solution the yields are low unless the aromatic diazo compounds contain strongly negative substituents, such as nitro groups, in the ortho and para positions (as in 2,4-dinitrobenzenediazo-nium chloride, for example). 

Fig (23) Acid (193) prepared from bromoanisole (190) by standard organic reactions, undergoes cyclization with polyphosphoric acid leading the formation of tetralone (194). A Reformatsky reaction on compound (194) with methyl g-bromocrotonate followed by aromatization produces compound (195). It is converted to compound (196) by treatment with methylmagnesium and cyclization. The corresponding phenol was oxidized to miltirone (197). 

Diorgano tellurium dicarboxylates were prepared from dialkyl and diaryl tellurium derivatives. Aliphatic carboxylic acids, aromatic carboxylic acids, their sodium or silver salts, and carboxylic acid anhydrides were used as reagents. Dicarboxylic acids such as succinic acid and phthalic acid were reported to give monomeric carboxylates when... 

Similarly, a series of m- and -substituted anilides 68 of thienoic acid were prepared and their H NMR spectroscopic characteristics were examined. In general, good correlations were observed between the chemical shifts of proton signals of the acyl aromatic rings and the Hammett . 

Poly(amic acids) were prepared by the ambient temperature condensation of 1,2,3,4-cyclobutane tetracarboxylic dianhydride with selected aromatic diamines. When the poly(amic acids) and liquid crystal alignment agents y-butyrolactone and A-methyl-pyrrolidone were spin-coated and cured onto an inert surface, the polyimide was effective as a liquid crystal aligner. 

Phenolic esters are obtained similarly. The presence of a nitro group in the aromatic nucleus and the use of pyridine as solvent facilitates the reaction. This reaction is recommended for the characterization of phenols. 2,4,5-Trichlorophenyl-, pentachlorophenyl-, 4-nitrophenyl- and thiophenyl esters of N-acylamino acids are prepared in this manner. These aromatic esters are used in the stepwise lengthening of peptides, du Vigneaud and coworkers synthesized lysine vasopressin from a nonapeptide which they prepared stepwise using the nitrophenyl ester method. Room temperature esterification of dicarboxylic acids and diphenols are also carbodiimide mediated using the 1 1 complex derived from DMAP and p-toluenesulfonic acid as catalyst Methacrylic acid is also esterified with phenols using carbodiimides and DMPA to mediate the reaction. ... 

Benzenesulfonic acids arc prepared by direct suifonation of aromatic hydrocarbons. 

Aromatic carboxylic acids are prepared by reaction of a Grignard reagent with carbon dioxide, as either the solid or gas (Scheme 10.9). 

Solid-phase synthesis of substituted pyrazolones 550 from polymer-bound /3-keto esters 549 has been described (Scheme 68) <2001EJ01631>. Trisubstituted pyrazole carboxylic acids were prepared by reaction of polymer-bound arylidene- or alkylidene-/3-oxo esters with phenylhydrazines <1999S1961>. 2-(Pyrazol-l-yl)pyrimi-dine derivatives were prepared by cyclocondensation of ethyl acetoacetate and (6-methyl-4-oxo-3,4-dihydropyrimi-din-2-yl)hydrazine with aromatic aldehydes <2004RJC423>. Reactions of acylated diethyl malonates with hydrazine monohydrochloride in ethanol afforded 3,4-disubstituted-pyrazolin-5-ones <2002T3639>. Reactions of hydrazines with A -acetoacetyl derivatives of (45 )-4-benzyloxazolidin-2-one (Evans oxazolidinone) and (2R)-bornane-10,2-sultam (Oppolzer sultam) in very acidic media gave pyrazoles retaining the 3(5)-chiral moiety <1999S157>. 

The halogen ring-substituted acids are prepared by some one of the general methods of synthesis, depending on whether the desired product is the ortho, meta or para compound. The meta acids are made by direct action of a halogen on the aromatic acid. 

---