A comparative LFER study of the reactivity of pyridineacetic, pyridineacetic acids N-oxide and substituted phenylacetic acids with diazodiphenylmethane in various alcohols

Abstract

Rate constants have been determined for the reactions of diazodiphenylmethane (DDM) with 3- and 4-pyridineacetic acid, 3- and 4-pyridineacetic acid N-oxide and some meta- and para-substituted phenylacetic acids in twelve alcohols. The determined rate constants, together with literature data, were used for calculation of Hammett ρ values in a series of alcohols. Secondary ρ constants have been calculated for substituents in meta and para-position of phenylacetic acids not given in literature, and also ρ constants for 3N, 3N-O, 4N and 4N-O in pyridineacetic acids, in alcohols used. The transmission of electronic effects through the phenylacetic acid system and pyridineacetic system is compared with that in benzene and pyridine. The multiple correlation of log k values for reaction of above acids in 12 alcohols with group of suitable solvent parameters was very successful. .

Određene su konstante brzine reakcije esterifikacije 3- i 4-piridinsirćetne kiseline, 3- i 4-piridin-N-oksid-sirćetne kiseline i nekih meta i para-supstituisanih fenilsirćetnih kiselina sa diazodifenilmetanom na 30 ºC u dvanaest alkoholnih rastvarača. Na osnovu dobijenih konstanti brzina reakcija piridinsirćetnih kiselina i supstituisanih fenilsirćetnih kiselina izračunate su nove sekundarne ρ konstante supstituenata. Takođe su korišćenjem Hammett-ove jednačine određene reakcione konstante ρ za navedene kiseline i diskutovan je efekat prigušenja metilenske grupe. Višestrukom regresionom analizom uspostavljena je zadovoljavajuća zavisnost konstanti brzina reakcija kao i reakcione konstante ρ sa parametrima rastvarača kao što su: Kirkwood-ova funkcija relativne permitivnosti f(ε), Taftova ρ* konstanta za alkil grupe alkohola i nγH koji predstavlja broj γ-vodonikovih atoma u alkoholu. .