ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Reaction sites of N,N′-substituted p-phenylenediamine antioxidants

I. Kortišová, M. Breza, and Z. Cibulková

Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia

E-mail: breza@cvt.stuba.sk

Received: 6 June 2006  Revised: 25 July 2006  Accepted: 31 July 2006

Abstract: The geometries of N,N′-diphenylbenzene-1,4-diamine (DPPD), N-phenyl-N′-(1-phenylethyl)benzene-1,4-diamine (SPPD), N-(4-methylpentan-2-yl)-N′-phenylbenzene-1,4-diamine (6PPD), N-propan-2-yl-N′-phenylbenzene-1,4-diamine (IPPD), N-(2-methoxybenzyl)-N′-phenylbenzene-1,4-diamine (MBPPD), and N-phenyl-N′-(2-phenylpropan-2-yl)benzene-1,4-diamine (CPPD) as well as of their dehydrogenation products were optimized by the semiempirical AM1 method. The results support the idea of stable N_B=C_X structures formation during the consecutive dehydrogenation of SPPD, 6PPD, IPPD, and MBPPD antioxidants. The biradicals formed during the second step of dehydrogenation of substituted phenylenediamines might be important for their antioxidant effectiveness.

Keywords: antioxidants - N,N′-substituted p-phenylenediamines - semiempirical AM1 method of quantum chemistry - geometry optimization

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-006-0097-6

Chemical Papers 61 (1) 61–65 (2007)