The heats of formation of Cs and C, alkyl nitrites (RONO) have been determined via their heats of combustion by bomb calorimetry, thereby providing a complete set of values of AH'/ for CI-C, alkyl nitrites. The experimental values are in excellent agreement with values derived from group additivity rules. For branched compounds these calculations involve corrections for gauche interactions. In these cases, the gauche interactions are reflected in the activation energies El determined by recent kinetic studies, required for breaking the RO-NO bond.The hcats of formation of the alkoxy radicals involved together with AH",(NO) = 21.6 kcal/mole leads to the result D(R0-NO) = 41.5 f 1 kcal/mole. The concordance between D(thermochemica1) and D(kinetic), unlike previous kinetic studies, implies that E t = 0 =k 1 kcal/mole.
The synthesis and antiallergic activity of a series of 2-hydroxy-N-1H-tetrazol-5-ylbenzamides and isomeric N-(2-hydroxyphenyl)-1H-tetrazole-5-carboxamides is described. A relationship between structure and intravenous antiallergic activity in the rat passive cutaneous anaphylaxis (PCA) test has been established using a Hansch/Free-Wilson model and used to direct studies toward potent derivatives. The contribution of physicochemical properties to activity is discussed. One member of this series, N-(3-acetyl-5-fluoro-2-hydroxyphenyl)-1H-tetrazole-5-carboxamide (3f), which was selected for further evaluation, has an ID50 value of 0.16 mg/kg po and is 130 times more potent than disodium cromoglycate (DSCG) on intravenous administration.
1,3,4-0xadiazolium salts react with a wide variety of primary amines and ammonia to yield s-triazolium salts and s-triazoles, respectively; s-triazolo [I ,5-a] pyridinium salts and s-triazolo [1,5-a] pyridines are formed from 1,3,4-oxadiazolo[3.2-a] pyridinium perchlorates. Intermediate oxadiazolines or amidrazones resulting from attack of the amine a t C-2 of the oxadiazolium ring have been isolated from the reactions of triphenyloxadiazolium perchlorate with aniline, butylamine, secondary amines, and hydrazines. The subsequent fate of these intermediates depends on the nature of the amine and the conditions used.WE have recently described the synthesis of 1,3,4-When triphenyloxadiazolium perchlorate (1 a) is oxadiazolium salts (1) l p 2 and their conversion into heated with aniline in acetic acid the tetraphenyltri-N-aryl-s-triazolium salts (2) on treatment with primary azolium salt (2a) rapidly separates. The reaction was aromatic a m i n e ~. ~ This reaction resembles the form-extended to a wide range of oxadiazolium salts and ation of pyridinium salts from pyrylium salts and primary aromatic amines (see Table ) and at the time primary amines, a reaction that is widely applicable and constituted the first synthesis of lJ4-diaryl-1,2,4-trithat proceeds in both strongly and weakly basic media.4 azolium salts lacking functional groups.s Noteworthy Yield
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.