Computational analysis of the solvent effect on the barrier to rotation about the conjugated C-N bond in methyl N,N-dimethylcarbamate

被引:76
作者
Rablen, PR [1 ]
机构
[1] Swarthmore Coll, Dept Chem, Swarthmore, PA 19081 USA
关键词
D O I
10.1021/jo000945z
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
It is known experimentally that, in contrast to the case of amides, barriers to rotation about the conjugated C-N bonds of carbamates show very little solvent dependence. Calculations of the relative solvation energies of the equilibrium and transition state structures of methyl N,N-dimethylcarbamate (MDMC) and N,N-dimethylacetamide (DMA) were carried out using a continuum reaction field model in order to investigate the reason that bulk solvent polarity raises the barrier for DMA but leaves the barrier for MDMC unchanged. The results confirmed that MDMC is insensitive to bulk solvent polarity, probably as a result of the relatively small molecular dipole moment. Calculations of proton affinities and of the strength of association with a single water molecule were then performed in order to investigate why hydrogen-bond-donating solvents affect DMA but not MDMC. These calculations showed that MDMC is a less capable hydrogen-bond acceptor than DMA, and that the rotational barrier of MDMC does not increase in response to protonation or hydrogen-bonding nearly as much as the barrier of DMA does. Both of these factors contribute to making the rotational barrier of MDMC insensitive to solvent hydrogen-bond donor ability.
引用
收藏
页码:7930 / 7937
页数:8
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共 51 条
[41]   NUCLEAR MAGNETIC RESONANCE STUDIES OF AMIDES [J].
STEWART, WE ;
SIDDALL, TH .
CHEMICAL REVIEWS, 1970, 70 (05) :517-&
[42]   SEMIANALYTICAL TREATMENT OF SOLVATION FOR MOLECULAR MECHANICS AND DYNAMICS [J].
STILL, WC ;
TEMPCZYK, A ;
HAWLEY, RC ;
HENDRICKSON, T .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1990, 112 (16) :6127-6129
[43]   PROTON NMR-STUDIES OF SYMMETRICALLY SUBSTITUTED N,N-DIALKYLTRIFLUOROACETAMIDES - MEDIUM EFFECTS [J].
SUAREZ, C ;
LEMASTER, CB ;
LEMASTER, CL ;
TAFAZZOLI, M ;
TRUE, NS .
JOURNAL OF PHYSICAL CHEMISTRY, 1990, 94 (17) :6679-6683
[44]   MOLECULAR-INTERACTIONS IN SOLUTION - AN OVERVIEW OF METHODS BASED ON CONTINUOUS DISTRIBUTIONS OF THE SOLVENT [J].
TOMASI, J ;
PERSICO, M .
CHEMICAL REVIEWS, 1994, 94 (07) :2027-2094
[45]   THEORETICAL CHEMISTRY IN SOLUTION - SOME RESULTS AND PERSPECTIVES OF THE CONTINUUM METHODS AND IN PARTICULAR OF THE POLARIZABLE CONTINUUM MODEL [J].
TOMASI, J ;
BONACCORSI, R ;
CAMMI, R ;
DELVALLE, FJO .
JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM, 1991, 80 :401-424
[47]   SOLVENT EFFECTS ON 1,2-DIHALOETHANE GAUCHE/TRANS RATIOS [J].
WIBERG, KB ;
KEITH, TA ;
FRISCH, MJ ;
MURCKO, M .
JOURNAL OF PHYSICAL CHEMISTRY, 1995, 99 (22) :9072-9079
[48]   RESONANCE INTERACTIONS IN ACYCLIC SYSTEMS .3. FORMAMIDE INTERNAL-ROTATION REVISITED - CHARGE AND ENERGY REDISTRIBUTION ALONG THE C-N BOND ROTATIONAL PATHWAY [J].
WIBERG, KB ;
BRENEMAN, CM .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1992, 114 (03) :831-840
[49]   AMIDES .3. EXPERIMENTAL AND THEORETICAL-STUDIES OF THE EFFECT OF THE MEDIUM ON THE ROTATIONAL BARRIERS FOR N,N-DIMETHYLFORMAMIDE AND N,N-DIMETHYLACETAMIDE [J].
WIBERG, KB ;
RABLEN, PR ;
RUSH, DJ ;
KEITH, TA .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1995, 117 (15) :4261-4270
[50]   HARTREE-FOCK 2ND DERIVATIVES AND ELECTRIC-FIELD PROPERTIES IN A SOLVENT REACTION FIELD - THEORY AND APPLICATION [J].
WONG, MW ;
WIBERG, KB ;
FRISCH, MJ .
JOURNAL OF CHEMICAL PHYSICS, 1991, 95 (12) :8991-8998