105735-34-0Relevant articles and documents
Mechanism of 1H,1H; 1H,13C; 13C,13C spin-spin coupling constants in benzyl cyanide and some derivatives. Experimental and theoretical estimates of internal rotational potentials.
Schaefer, Ted,Penner, Glenn H.
, p. 2013 - 2020 (2007/10/02)
The mechanisms of longe-range spin-spin coupling constants involving the methylene protons and 13C nucleus of the cyano group are discussed for benzyl cyanide.Analysis of the 1H nmr spectrum of benzyl cyanide-8-13C in benzene-d6 solution yields nJ(H,CH2) and nJ(H,13CN) for = 4-6.Similar data are reported for the 2,6-dichloro and 2,6-difluoro derivatives, together with some sign determinations. nJ(13C,13CN), n = 1-5, are given for the three compounds.It is shown that all these parameters are consistent with a small barrier to internal rotation about the Csp2 - Csp3 bond in benzyl cyanide in solution.Computations at various levels of molecular orbitael theory agree that this barrier is small.The nJ(13C,13CN) imply a stabilization in polar solvents of the conformation in which the cyano group of benzyl cyanide lies in a plane perepndicular to the benzene plane.The molecular orbital calculations indicate a predominantly twofold nature of the internal barrier, although a significant fourfold component is also present.The coupling constants cannot discern the presence of the fourfold component for benzyl cyanide nor for its 2,6-difluoro derivate. 1J(13C,13CN) is solvent dependent.A table of the computed sidechain geometries is appended.
