Absorption spectroscopic investigations on M[Al (OC₃H₇ⁱ)₄]₃(M = Pr, Nd) - catalysed reduction of ketones

Bimetallic isopropoxides M[Al(OC3Hi7)4]3 (M = Pr, Nd)—catalyzed reduction of 2-octanone and benzophenone

“…Hence a simple kinetic equation, k obs = d[1]/dt, was assumed for calculation of reaction rates. Similarly these rates were also calculated [25] by plotting oscillator strengths (P ) with time and are given correspondingly in parentheses in (3)) involves the reduction of the keto (>C=O) group to the corresponding secondary alcoholic (>CH-OH) group using aluminum isopropoxide as the catalyst [32,33]. After completion of the reaction, the reaction mixture is acidified with sulfuric acid and then the product is distilled off: The reaction proceeds through coordination of ketone and alcohol by forming a 6-membered cyclic transition state complex as shown in reaction (4) Hence the increase in the intensity of the bands with time is assigned to the formation of the intermediate complex 1, as given in reaction (4), which results in the formation of the final reduced product alcohol and oxidized product acetone.…”

“…The values of both P and T λ corresponding to all the transitions seen in Tables 1 and 2, were found to increase with time, accounting for the coordination of ketone and alcohol to form an intermediate complex which leads the reduction of ketone. (Table 3) spectrophotometrically [25] by obtaining the maximum absorbances reached at the end of each kinetic run. Timedependence absorbances were noted corresponding to all the said bands and these absorbances were converted into concentrations in which the concentrations corresponding to maximum absorbances were considered to be equivalent to initial concentrations of bimetallic isopropoxide.…”

“…These spectral investigations have helped in following the kinetics of simultaneous complexation of two [21,22], three [23], or even four [24] chemically different metal ions with large multidonor biomolecular ligands cited above and we could determine the rate constants for these multimetal complexation reactions. We therefore considered it worthwhile to investigate the Pr[Al(-OC 3 H i 7 ) 4 ] 3 -and Nd[Al (-OC 3 H i 7 ) 4 ] 3 -catalyzed MPV reduction [25] of 2-octanone and benzophenone to the corresponding secondary alcohols, probed through comparative absorption and their spectral intensities involving 4f -4f transitions. These spectral investigations have the potential to help in the determination of rate constants for these reactions with respect to the individual 4f -4f bands as well as for the spectra as a whole.…”