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Summary Treatment of alkaline phosphatase(s) from dog intestine with cysteine causes the complete destruction of its enzymatic activity without impairing its ability to combine with and be precipitated by its antiserum. Treatment of the enzyme with acetic anhydride, although leaving its catalytic properties largely intact, destroys the ability of the enzyme to be precipitated by antiserum. However, combination with antibody, in the form of soluble complexes still takes place. These complexes are precipitated upon the addition of horse antirabbit γ-globulin antibodies. The relation of these observations to the chemical nature of the catalytic and antigenic sites of alkaline phosphatase is discussed.

The formylation of amino acids with acetic formic anhydride has been studied. This anhydride is prepared by the reaction of acetyl chloride with sodium formate or, preferably, from ketene and formi...

When acetic acid is handled in aluminum, it is important, for reasons of corrosion resistance, that the acid be not completely anhydrous, a condition that results if traces of acetic anhydride are present. A quick colorimetric test depending on the reaction between acetic anhydride with aniline has been developed by which it is possible to detect 0.05% acetic anhydride in acetic acid.

This reaction at 35°C. exhibits a behavior indicative of the presence of an intermediate in the reaction. Reaction of paraformaldehyde and ammonium nitrate in glacial acetic acid resulted in the isolation of hexamine dinitrate. Evidence is presented to indicate that formation of hexamine dinitrate, accompanied by the production of nitric acid, is responsible for the production of RDX in the acetic anhydride system.

The specificity of the Barrnett-Seligman method for the histochemical demonstration of α-acylamido carboxyl groups (C terminal) of proteins is dependent on the conversion of such groups to ketones by the action of acetic anhydride and absolute pyridine. Studies on model compounds show that the side-chain carboxyl groups also react in the method and that most of the final color developed can be attributed to these carboxyls, rather than to the C terminal carboxyl groups. It is postulated that the side-chain carboxyls react by formation of mixed anhydrides in the presence of acetic anhydride and pyridine. This mixed anhydride then could link with a hydrazide to form a dihydrazide, which is capable of coupling with a diazo dye. Acetic anhydride treatment alone, without pyridine, also yields mixed anhydride. The mixed anhydride derived from the side-chain carboxyls can be destroyed by base, whereas the methyl ketone derived from the C terminal carboxyl is unaffected, and this treatment makes the method specific for C terminal carboxyl groups. Tissues treated in such a fashion demonstrate that all the color reaction obtained in the method is due to side-chain carboxyls, and that C terminal groups yield little or no staining as would be expected for "average" molecular weight proteins.

FOR the synthesis of esters from carboxylic acids and alcohols or phenols, it is customary to heat the reactants for several hours in the presence of a strong mineral acid catalyst, or else to proceed via the acid chloride or the acid anhydride. We now report a method of esterifleation which obviates the necessity of a two-stage process and, at the same time, enables a rapid direct reaction to occur between the acid and the hydroxy-compound under mild conditions. The new method, which entails the use of the anhydride of trifluoracetic acid, gives the purified esters in yields of 60–90 per cent.