Acid chlorides formation

Acid Chloride Formation. Monoacid chlorides of maleic and fumaric acid are not known. Treatment of maleic anhydride or maleic acid with various reagents such as phosgene [75-44-5] (qv), phthaloyl chloride [88-95-9] phosphoms pentachloride [10026-13-8] or thionyl chloride [7719-09-7] gives 5,5-dichloro-2(5JT)furanone [133565-92-1] (4) (26). Similar conditions convert fumaric acid to fumaryl chloride [627-63-4] (5) (26,27). NoncycHc maleyl chloride [22542-53-6] (6) forms in 11% yield at 220°C in the reaction of one mole of maleic anhydride with six moles of carbon tetrachloride [56-23-5] over an activated carbon [7440-44-4] catalyst (28). 

Pigment Red 144 [5280-784] 20735 disa2o condensation coupling of dia2oti2ed 2,5-dichloroaniline with 3-hydroxy-2-napthoic acid, foUowed by acid chloride formation and reaction with 2-chloro-/)-phen5iene- diamine... 

Esterification, Amidation, and Acid Chloride Formation. Amino acids undergo these common reactions of the carboxyl group with due regard for the need for A/-protection. 

Reactions of the carboxyl group include salt and acid chloride formation, esterification, pyrolysis, reduction, and amide, nitrile, and amine formation. Salt formation occurs when the carboxyUc acid reacts with an alkaline substance (22)... 

Acid Chloride Formation. Neopentanoic acid can be converted to neopentanoyl chloride [3282-30-2] by reaction with thionyl chloride (2), phosgene (3), phosphoms pentachloride, phosphoms trichloride, or by the reaction with henzotrichloride ia the presence of Eriedel-Crafts catalysts (4). A laboratory procedure usiag tetramethyl-a-halogenoenamines at room temperature has also been reported (5). 

Condensa.tlon, This term covers all processes, not previously iacluded ia other process definitions, where water or hydrogen chloride is eliminated ia a reaction involving the combination of two or more molecules. The important condensation reactions are nitrogen and sulfur heterocycle formation, amide formation from acid chlorides, formation of substituted diphenyl amines, and misceUaneous cyclizations. 

Pyrimidinecarboxylic acid chlorides formation, 3, 80 Pyrimidinecarboxylic acids acidic pK , 3, 60 decarboxylation, 3, 80 esterification, 3, 80 esters... 

The TBDMS ester can be converted directly to an acid chloride [DMF, (COCl)2, It, CH2CI2] and then converted to another ester, with different properties, by standard means. This procedure avoids the generation of HCl during the acid chloride formation and is thus suitable for acid-sensitive substrates. ... 

The PCBM methyl ester can be used for coupling amine-containing ligands after removal of the methyl group and activation of the carboxylate using a number of different reaction strategies. Hummelen et al. (1995) successfully coupled cholestanol and histamine to the fuller-ene-PCBM derivative (after acid chloride formation) for use in fabrication of photodetectors and biological studies, respectively. For specific applications of PCBM-fullerenes, see Shaheen et al. (2001), Brabec et al. (2001), Yu et al. (1995), Mecher et al. (2002), Meijer et al. (2003), van Duren et al. (2004), and Anthopoulos et al. (2004). 

Phosphorus trichloride and phosphorus pentachloride are also suitable reagents for acid chloride formation, but their use is largely restricted to aromatic carboxylic acids. (Section 6.14.1, p. 1073). 

A serendipitous synthesis of the l,4-dioxepin-5-one derivative 228 has been reported based on acid chloride formation from the acid 227, followed by a ring opening and ring closing sequence on exposure of the acid chloride to 48% HBr solution [01TL2305]. 

Sulfinic acids and sulfoxides are not particularly common, being readily oxidized to the sulfonic acids and sulfones, respectively. Sulfonic acids have high melting points and probably exist as zwitterions. They are amphoteric, but mainly display the characteristics of weak acids. The sulfonic acid group activates an adjacent halogen to nucleophilic displacement, and may itself be displaced, e.g. reaction of alkylamines with benzimidazole-2-sulfonic acid. Imidazolesulfonic acids resist esterification and acid chloride formation, and are only hydrolyzed by concentrated hydrochloric acid at 170 °C the 2-isomers are more resistant than the 4- or 5-isomers. Aqueous alkali converts the free acids into hydroxy derivatives. Sulfonyl chlorides are accessible via the thiols (Section 4.07.3.6.1) which react with ammonia to form sulfonamides, or are reduced by tin(II) chloride to thiols (77JHC889). 

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