Dehalogenation/dehydrogenative

SCHEME 43.5. Lee et al. s stereoselective radical dehalogenation/dehydrogenative cycUzation. 

Catalysts. In industrial practice the composition of catalysts are usuaUy very complex. Tellurium is used in catalysts as a promoter or stmctural component (84). The catalysts are used to promote such diverse reactions as oxidation, ammoxidation, hydrogenation, dehydrogenation, halogenation, dehalogenation, and phenol condensation (85—87). Tellurium is added as a passivation promoter to nickel, iron, and vanadium catalysts. A cerium teUurium molybdate catalyst has successfliUy been used in a commercial operation for the ammoxidation of propylene to acrylonitrile (88). 

Dehalogenating reduction Salt elimination Disproportionation Electrochemical formation Dehydrogenative catalytic coupling... 

The procedure described is essentially that of Ballard and Dehn.1 Stilbene has also been prepared by reduction of desoxy-benzoin,20 benzaldehyde,23 and benzil 2o-2c by dehydrogenation of ethyl benzene,30 toluene,30- 33- 3, and bibenzyl 33-3alkaline reduction of phenylnitromethane,40 phenylnitroacetonitrile,40 and desoxybenzoin 43 by distillation of benzyl sulfone,50 benzyl sulfide,60-63 calcium cinnamate,5 cinnamic acid,5d phenyl cinna-mate,6e-6/ and diphenyl fumarate ie by dehydrohalogenation of a,a -dichlorobibenzyl60 and benzyl chloride 63 by dehalogenation of a,a,c/,a -tetrachlorobibenzyl70 and benzal chloride 73 by the coupling of cinnamic acid and phenyldiazonium chloride 8 by de-... 

The methylamination is less selective. This lower selectivity is due to the stronger nucleophilicity of methylamine as also shown by the methylamino-dehalogenation occurring with 2-chloro-5-nitroquinoxaline and 2-chloro-7-nitroquinoxaline into 2-amino-5-nitroquinoxaline and 2-amino-7-nitroquinoxaline, respectively. Amino-dehydrogenations with these compounds were not observed (see Scheme 22). It is important to note that 5-nitroquinoxaline gives methylamination at position ortho and para... 

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