Manual De Diagnostico De Plaguicidas

J.ORG.CHEM.1991, 56, 5111-5113
KINECS AND MECHANISM OF THE OXIDATION OF AROMATIC ALDEHYDES BY PYRIDINIUM FLUOROCHROMATE
SARSWATI AGARWAL, KAKULI CHOWDHURY,AND KALYANK. BANERJI*
DEPARTAMENT OF CHEMISTRY, UNIVESITY OF JODHPUR, 342 001, INDIA
RECEIVED FEBRUARY 7, 1991

KINETICS OFOXIDATION OF A NUMBER OF ORTHO-, META-, AND PARA –SUBSTITUTED BENZALDEHYDES BY PYRIDINIUM FLUOROCHOROMATE (PDC), IN DIMETHYL SULFOXIDE, WERE STUDIED. THE MAIN PRODUCT OF OXIDATION IS THE CORRESPONDINGBENZOIC ACID. THE REACTION IS FIRS ORDER WITH RESPECT TO PFC. MICHAELIS-MENTE-TYPE KINETICS WRE OBSERVEDE WITH RESPECT TO THE ALDEHYDE. THE FORMATION CONSTANTS OF THE INTERMEDIATE PFC- ALDEHYDECOMPLEXES AND THE RATES OF THEIR DECOMPOSITION WERE DETERMINED AT DIFFERENT TEMPERATURES. THE THERMODYNAMIC AND ACTIVATION PARAMETERS WERE ALSO DETERMINED. THE OXIDATION OF (2H) BENZALDEHYDE( PHCLDO)EXHIBITITED A SUBSTANTIAL PRIMARY KINETIC ISOTOPE EFFECT. THE RATES OF OXIDATION OF PARA- AND META –SUBSTITUTED COMPOUNDS, THE BEST CORRELATION IS OBSTAINNED WITH TAFT’S 61 AND 6R+; THEMETA-SUBSTITUTED BENZALDEHYDES CORRELATED BEST WITH 61 AN 6R0 .
THE RATES OF OXIDATION OF THE ORTHO COMPUNDS CORRELATED BEST WITH A TRIPARAMETRIC EQUATION INVOLVING TAFT’S 61 AN 6R+ AND CHARTON’S STERICPARAMETER, V. ANALYSIS OF THE RATE OF OXIDATION OF BENZALDEHYDE IN 19 ORGANIC SOLVENTS INDICATED THE GREATER IMPORTANCE OF CATION- SOLVATING POWER OF THE SOLVENTS. A MECHANISM INVOLVING TRANSFER OF AHYDRIDE ION FROM THE ALDEHYDE TO PFC HAS BEEN PROPOSED.

PYRIDINIUM FLUOROCHROMATE (PFC) IS A VERSATILE OXIDANT.1 KINETICS OF OXIDATION OF ALIPHATIC ALDEHYDES BY PFC HAVE BEEN REPORTED PREVIOUSLYFROM THIS LABORATORY.2HOWEVER, AROMATIC AND ALIPHATIC ALDEHYDES ARE REPORTED TO FOLLOW DIFFERENT MECHANISTIC PATHWAYS IN REACTIONS WITH MANY OXIDANTS,E.G., CHROMIC ACID,3 PERMANGANATE ION,4 AND...