CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY

Activation parameters for the rotation around the methylene-nitrogen single bond found in a series of four 2,2´-disubstituted N-acetyl-N-phenylbenzylamines, dissolved in DMSO-d6, were measured employing the temperature dependence of the ¹H-NMR spectrum lineshape between 340 and 400 K. The results ar...

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Autores principales:	WEISS-LOPEZ,BORIS E, JULLIAN,CAROLINA, SAITZ,CLAUDIO, PESSOA-MAHANA,HERNAN, VALDERRAMA,JAIME, ARAYA-MATURANA,RAMIRO
Lenguaje:	English
Publicado:	Sociedad Chilena de Química 2001
Materias:	Conformational Dynamics ¹H-NMR N-AcetyPhenylbenzylamines AM1-MO
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442001000300005
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spelling	oai:scielo:S0366-164420010003000052002-02-05CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDYWEISS-LOPEZ,BORIS EJULLIAN,CAROLINASAITZ,CLAUDIOPESSOA-MAHANA,HERNANVALDERRAMA,JAIMEARAYA-MATURANA,RAMIRO Conformational Dynamics ¹H-NMR N-AcetyPhenylbenzylamines AM1-MO Activation parameters for the rotation around the methylene-nitrogen single bond found in a series of four 2,2´-disubstituted N-acetyl-N-phenylbenzylamines, dissolved in DMSO-d6, were measured employing the temperature dependence of the ¹H-NMR spectrum lineshape between 340 and 400 K. The results are : (I) 2 [N-acetyl -N- (2-acetamidophenyl) aminomethyl]phenylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 79.9±2.0 kJ/mol (370K), deltaH<FONT FACE=Symbol>¹</FONT > or = 96.2±6.0 kJ/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = +45±20 J/Kmol; (II) 2 - [N acetyl N - (2-acetyloxybenzyl)amino]benzylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 82.0±2.0 kJ/mol (370K), deltaH<FONT FACE=Symbol>¹</FONT > or = 79.1±6.0 kcal/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = -8±20 J/Kmol; (III) 2 - [N Acetyl N (2-nitrobenzyl)amino]benzylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 80.8±2.0 kJ/mol (380K), deltaH<FONT FACE=Symbol>¹</FONT > or = 60.7±6.0 kcal/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = -53±20 J/Kmol; (IV) 2-[NAcetylN-(2-acetyloxybenzyl)amino]phenylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 77.0±2.0 kJ/mol (370K), deltaH<FONT FACE=Symbol>¹</FONT > or = 65.3±6.0 kJ/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = -32±20 J/Kmol. Substitution at positions 2 and 2´ with bulky groups appears to be essential to freeze the gauche structure at room temperature and consequently, the main contribution to the barrier arises from the steric hindrance between these two groups. Structure I shows an anomalous behavior, possibly due to the formation of a hydrogen bond between the NH at position 2´ and the solvent. This interaction increases deltaHpi and freezes the rotation around the aryl-nitrogen bond, increasing deltaS<FONT FACE=Symbol>¹</FONT>info:eu-repo/semantics/openAccessSociedad Chilena de QuímicaBoletín de la Sociedad Chilena de Química v.46 n.3 20012001-09-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442001000300005en10.4067/S0366-16442001000300005
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Conformational Dynamics ¹H-NMR N-AcetyPhenylbenzylamines AM1-MO
spellingShingle	Conformational Dynamics ¹H-NMR N-AcetyPhenylbenzylamines AM1-MO WEISS-LOPEZ,BORIS E JULLIAN,CAROLINA SAITZ,CLAUDIO PESSOA-MAHANA,HERNAN VALDERRAMA,JAIME ARAYA-MATURANA,RAMIRO CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY
description	Activation parameters for the rotation around the methylene-nitrogen single bond found in a series of four 2,2´-disubstituted N-acetyl-N-phenylbenzylamines, dissolved in DMSO-d6, were measured employing the temperature dependence of the ¹H-NMR spectrum lineshape between 340 and 400 K. The results are : (I) 2 [N-acetyl -N- (2-acetamidophenyl) aminomethyl]phenylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 79.9±2.0 kJ/mol (370K), deltaH<FONT FACE=Symbol>¹</FONT > or = 96.2±6.0 kJ/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = +45±20 J/Kmol; (II) 2 - [N acetyl N - (2-acetyloxybenzyl)amino]benzylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 82.0±2.0 kJ/mol (370K), deltaH<FONT FACE=Symbol>¹</FONT > or = 79.1±6.0 kcal/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = -8±20 J/Kmol; (III) 2 - [N Acetyl N (2-nitrobenzyl)amino]benzylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 80.8±2.0 kJ/mol (380K), deltaH<FONT FACE=Symbol>¹</FONT > or = 60.7±6.0 kcal/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = -53±20 J/Kmol; (IV) 2-[NAcetylN-(2-acetyloxybenzyl)amino]phenylacetate deltaG<FONT FACE=Symbol>¹</FONT > or = 77.0±2.0 kJ/mol (370K), deltaH<FONT FACE=Symbol>¹</FONT > or = 65.3±6.0 kJ/mol and deltaS<FONT FACE=Symbol>¹</FONT > or = -32±20 J/Kmol. Substitution at positions 2 and 2´ with bulky groups appears to be essential to freeze the gauche structure at room temperature and consequently, the main contribution to the barrier arises from the steric hindrance between these two groups. Structure I shows an anomalous behavior, possibly due to the formation of a hydrogen bond between the NH at position 2´ and the solvent. This interaction increases deltaHpi and freezes the rotation around the aryl-nitrogen bond, increasing deltaS<FONT FACE=Symbol>¹</FONT>
author	WEISS-LOPEZ,BORIS E JULLIAN,CAROLINA SAITZ,CLAUDIO PESSOA-MAHANA,HERNAN VALDERRAMA,JAIME ARAYA-MATURANA,RAMIRO
author_facet	WEISS-LOPEZ,BORIS E JULLIAN,CAROLINA SAITZ,CLAUDIO PESSOA-MAHANA,HERNAN VALDERRAMA,JAIME ARAYA-MATURANA,RAMIRO
author_sort	WEISS-LOPEZ,BORIS E
title	CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY
title_short	CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY
title_full	CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY
title_fullStr	CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY
title_full_unstemmed	CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY
title_sort	conformational dynamics of substituted n-acetyl-n-phenylbenzylamines. 1h-dnmr and am1-mo study
publisher	Sociedad Chilena de Química
publishDate	2001
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442001000300005
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CONFORMATIONAL DYNAMICS OF SUBSTITUTED N-ACETYL-N-PHENYLBENZYLAMINES. 1H-DNMR AND AM1-MO STUDY

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