ABSTRACT
The influence of carbon monoxide concentration on the kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a phosphite-modified rhodium catalyst has been studied for the pressure range p(CO)=0.20-3.83â MPa. Highly resolved time-dependent concentration profiles of the organometallic intermediates were derived from IR spectroscopic data collected in situ for the entire olefin-conversion range. The dynamics of the catalyst and organic components are described by enzyme-type kinetics with competitive and uncompetitive inhibition reactions involving carbon monoxide taken into account. Saturation of the alkyl-rhodium intermediates with carbon monoxide as a cosubstrate occurs between 1.5 and 2â MPa of carbon monoxide pressure, which brings about a convergence of aldehyde regioselectivity. Hydrogenolysis of the acyl intermediate is fast at 30 °C and low pressure of p(CO)=0.2â MPa, but is of minus first order with respect to the solution concentration of carbon monoxide. Resting 18-electron hydrido and acyl complexes that correspond to early and late rate-determining states, respectively, coexist as long as the conversion of the substrate is not complete.
ABSTRACT
An environmentally friendly and mild procedure to obtain 2,3-dihydroquinazolin-4(1H)-ones from 2-aminobenzonitriles and aromatic aldehydes has been developed. The reactions took place in water with inorganic base (K3PO4) as the only promoter. Various desired products have been prepared in moderate to good yields under identical conditions. Further transformation of dihydroquinazolinones to quinazolinones was carried out as well with TBHP as the oxidant.
