Benzoyl chloride, reaction with amino group

Acyl chlorides react readily with amino groups to form amides. The reactions (Figure 1) are carried out in an alkaline medium (Schotten-Baumann conditions). The use of amide derivatives for the HPLC analysis of amines has been widely studied. Clark and Wells [9] described several acyl chlorides such as p-nitrobenzoyl, p-methoxy-benzoyL p-methylbenzoyl and p-chlorobenzoyl chlorides. The spectrophotometric properties of their benzamides were investigated. The methoxybenzamides showed the most intense absorption at 252 nm, and therefore most fixed-wavelength (254 nm) UV detectors can conveniently be used for detection. The reaction of p-methoxybenzoyl chloride with some amines and the molar absorptivities of the derivatives are shown in Table I. 

Reaction of 2,3-dichlorobenzoyl chloride with cyanide ion leads to the corresponding benzoyl cyanide (141). Condensation of that reactive intermediate with aminoguanidine 142 leads to the hydrazone-like product 143. Treatment with base results in addition of one of the guanidine amino groups to the nitrile function and formation of the 1,2,4-triazine ring. The product, lamo-trigine (144), is described as an anticonvulsant agent [31]. 

The properties and reactions of amino-alcohols, obtained largely by hydrolysis of naturally occurring alkaloids, were investigated primarily for the purposes of structural analysis and the preparation of physiologically active derivatives. Many authors have described acylation of pyrrolizidine alcohols with benzoyl chloride and acetic anhydride (see, e.g., refs. 83 and 101). Trachelanthamidine benzoate and p-aminobenzoate were prepared especially for testing of their physiological activity.102 The p-aminobenzoate was obtained by treatment of trachelanthamidine with p-nitrobenzoyl chloride and subsequent reduction of the nitro group with iron in 20% acetic acid. The compound exhibited an anesthetic activity close to that of cocaine. 

We must keep in mind that ions II and III, which contain a free —NH2 or —COOH group, are in equilibrium with dipolar ion I consequently, amino acids undergo reactions characteristic of amines and carboxylic acids. As ion II is removed, by reaction with benzoyl chloride, for example, the equilibrium shifts to supply more of ion II so that eventually the amino acid is completely benzoylated. 

For the introduction of the benzoyl group (benzoylation) the procedure generally adopted is to use benzoyl chloride in dilute (10 per cent) alkaline solutions. Since benzoyl chloride reacts slowly with water at room temperature, the amino compound reacts fairly rapidly when shaken with it. The hydrogen chloride produced in the acylation is removed by the alkali. This method is known as the Schotten-Baumann reaction. The benzoyl derivatives nearly always crystallize well. The product is recrystallized to remove adsorbed and occluded impurities. If the derivative does not crystallize well, then a substituted benzoyl chloride is used, for example, p-nitrobenzoyl chloride. It will be recalled that for the characterization of the alcohols use was made of 3, 5-dinitrobenzoyl chloride. 

Aminoanthraquinones undergo acylation with acid chlorides, generally in organic solvent, and with carboxylic acids or anhydrides in oleum. Benzoylation is an important reaction, since many vat dyes contain benzamido groups in the a- (1-) position. The free amino groups may be diazotized to afford biaryl compounds. The great lability of substituents in anthraquinones, as compared with similar benzene and naphthalene compounds, offers a number of routes to aminoanthraquinones. 

Amino groups in dithioacetals undergo normal substitution reactions. Conventional reactions have been reported to occur with acetic anhydride,88,90,91 benzoyl chloride,46,92 l-fluoro-2,4-dinitrobenzene,250 p-toluenesulfonyl chloride,247 and benzyloxycarbonyl chloride92 the reported92 application of sodium chloride and methyl iodide to the conversion of 2-amino-2-deoxy-D-glucose diethyl dithioacetal hydrochloride into a pentamethyl derivative is presumed to be an error. Although crude 2-acetamido-2-deoxy-D-glucose diethyl dithioacetal was in one instance converted in low yield into a poorly... 

Acylation of the amino group at the 4-position of 3,4,5-triaminothiadia-zine 10b with trifluoroacetic acid, and with acetyl, benzoyl, caproyl, and p-toluenesulfonyl chloride, has been described (86FES862). The 4-aryl-diazonium salts have also been prepared (77JHC427), Reactions of 4,5-diaminothiadiazines are described with regard to the preparation of fused systems in Section II,C,2,a. 

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