Computational Study of Chemical Reactivity of Vinylpyrrole Derivatives

Abstract

The electrostatic potential V(r) and the average local ionization

energy. I(r) are discussed as a measure for the chemical reactivity

of 2- and 3-vinylpyrrole and their 1-methyl-2- or 4-formyl derivatives.

A survey of applications of DFT and ab initio SCF I(r)

computed on molecular surfaces defined by 0.00 1 au contour of the

electronic density  ρ(r)  was presented as a tool of chemistry. The

minima of both properties, V_s, _min and I_{s min},were located and

determined. Also, the energy gaps (LUMO_dienopbiles-HOMO_pyrrol)

were calculated, for three possible dienophiles and the pyrrole

derivatives. AM1//HF/3-21G based wavefunction was generated to

map both HOMO and LUMO of the derivatives to compare their

relative sizes. The electronic calculations showed that the 2-formyl-1-

methyl-4-vinylpyrrole, as a diene, is more reactive toward

dienophiles than the 4-formyl-1-methyl-2-vinylpyrrole. The

mapped orbitals indicated that a probable electrophilic attack would

be HOMO based.