Pyrolysis of aminonitriles, cyanohydrazones, and cyanoacetamides. Part I. Elimination reaction of 1-arylmethyleneamino-1,2-dihydro-4,6-dimethyl-2-oxopyridine-3-carbonitriles and substituted benzaldehyde cyanoacetylhydrazones

Abstract

Pyrolysis of the Schiff bases of 1‐arylmethyleneamino‐1,2‐dihydro‐4,6‐dimethyl‐2‐oxopyridine‐3‐carbonitriles (1–5) has been studied. These compounds eliminate via a six‐membered transition state to produce substituted benzonitriles and 2‐hydroxy‐4,6‐dimethylpyridine‐3‐carbonitrile. These eliminations are unimolecular first‐order reactions. The kinetic data gave a good correlation with σ0 values of the substituents on the aryl group with ρ = 0.83 at 520 K. Utilization of the pyrolytic reaction in synthesis of various benzonitriles is considered, and mechanistic information has been obtained by comparing the kinetic data and product analysis of the Schiff bases with their open‐chain substituted benzaldehyde cyanoacetylhydrazones (6–9) analogues. © 1996 John Wiley & Sons, Inc.

Theoretical Study on the Pyrolysis of Sulphonyl Oximes in the Gas Phase

“…This is due to the fact that the repulsive interaction between lone-pair electrons of O 3 and N 4 atoms is the smallest as they point towards the opposite directions. Atoms S 1 , O 3 , N 4 , C 5 , and H 6 are almost in a plane. It can be seen from Table 1 that the substituent on Y-ring does not change the structure of reactants significantly.…”

“…1,2 Some similar reactions have also been studied for 3-phenylhydrazonopentane-2,4-dione, 3 ethyl (hetero) arylcarboxylate esters, 4 and heterocyclic hydrazone 5 systems experimentally. The common character of these reactions is that they were found to be homegeneous and unimolecular, and follow firstorder rate law.…”

Gas-phase pyrolysis of 2-heteroaromatic-1-dimethylaminoethylenes: Kinetic and mechanistic study

“…phenylpyrimidine-5-carbonitrile (7). A mixture of 5-cyano-6-methyl-2-phenyl(3H)-pyrimidine-4-thione (0.01 mol; 2.27 g) and ethyl iodide (0.01 mol) was treated in acetone (10 ml) and (0.01 mol; 1.38 g) K 2 CO 3 .…”

“…In conjunction with our recent interest in adopting the environmentally friendly gas-phase technique in synthetic organic chemistry, we have previously reported on the utility of this technique for synthesis of substituted nitriles [6,7], ketones [8], and functionally substituted heteroaromatics. In the present article we report results of our efforts aimed at utilizing the same technique for syntheses of condensed pyridines utilizing the readily obtainable compounds (1-6) as starting materials [9] (See Scheme 1 for compound structures).…”

Article

“…Experimental details of both kinetic and reaction product analysis have been described in an earlier communication (16). For the kinetic investigations, a custom-made chemical data pyrolysis system, HPLC (Bio-Rad model 2700), Shimadzu UV-vis detector, Bio-Rad HPLC accessories, and Comark microprocessor and platinum resistance thermometers are used.…”