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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 19, Number 10
BKCSDE 19(10)
October 20, 1998 

Acid-Catalyzed Benzidine Rearrangement of Unsymmetrical Hydrazoaromatics
Koon Ha Park, Moon-Kyeu Park, Yoon Hwan Cho
Acid-catalyzed benzidine rearrangements of new unsymmetrical diazanes 1-3, prepared from the reduction of corresponding diazenes 4-6, were carried out in ethanolic solutions. The results are as follows; rearrangement of (3-carbomethoxyphenyl)(3-methoxyphenyl)diazane 1 gave 4,4'-diamino-2-carbomethoxy-2'-methoxybiphenyl 12 (p-benzidine type) in 71% and 10-amino-3-methoxyphenanthridin-6(5H)-one 13, 8-amino-3-methoxyphenanthridin-6(5H)-one 14 in 7.1% and 3.4%, respectively. Product 13 and 14 were formed by the condensation reaction of primarily formed o-benzidine and diphenyline type product, respectively. (5-Carbomethoxy-2-chlorophenyl)(4-methoxyphenyl)diazane 2 and (5-carbomethoxy-2-methylphenyl)(4-methoxyphenyl)diazane 3 underwent mainly disproportionations to give fission amines and corresponding diazenes in about 53% and 40% yields, respectively. The results obtained from the rearrangements of diazanes 1-3 indirectly indicated the importance of disproportionations to understand the benzidine rearrangements. The structures of benzidine rearrangement products were determined by usual NMR techniques such as DEPT, 2D H-H COSY, H-C COSY, 2D NOESY, and Gaussian function multiplication.
1090 - 1094
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