“…The authors showed that the C 2 v structure was more stable than the D 3 h one by 22.3 kJ mol -1 , in agreement with experimental data and preliminary EHT calculations . The calculated enthalpy of hydrogenation for the C 2 v species of 27.4 kJ mol -1 is close to the two available experimental values of 19.7 and 16.9 kJ mol -1 and agrees with the experimental observation that Co 2 (CO) 8 is readily converted to HCo(CO) 4 10a…”
Section: Generation Of the Active Speciessupporting
confidence: 88%
“…Due to the importance of this process, the study of its mechanism has always given rise considerable interest from both experimental and theoretical points of view. ,, The most widely accepted mechanism for the hydroformylation reaction of eq 1 catalyzed by HCo(CO) 4 is due to Heck and Breslow and involves five steps (see Scheme ). The same basic steps, but with the implication of a binuclear cobalt species in the last step of the mechanism, have been proposed by Orchin. 10a,c Likewise, the mechanism proposed by Wilkinson et al for the catalytic cycle mediated by HRh(CO) 2 (PPh 3 ) 2 consists of the same five steps: (i) ligand dissociation, (ii) olefin coordination, (iii) olefin insertion and PPh 3 addition, (iv) CO insertion, and (v) H 2 oxidative addition and aldehyde reductive elimination. 1 Heck and Breslow Mechanistic Proposal for the Hydroformylation Process…”
Section: Organometallic Reactions Involving Co or Co2mentioning
confidence: 53%
“…Hydroformylation allows the functionalization of CC bonds, and consequently it can be seen as an efficient synthetic route for the preparation of fine chemicals. It involves low-valent cobalt , and rhodium , complexes as catalysts, although other metals such as platinum, ruthenium, iridium, and palladium have also been employed, especially in the field of asymmetric hydroformylation . The overall equation for the formation of aldehydes from alkenes, dihydrogen, and carbon monoxide can be written as …”
Section: Organometallic Reactions Involving Co or Co2mentioning
confidence: 99%
“…Aldehydes react with HCo(CO) 4 to yield alcohols. , This is a side reaction in industrial catalytic processes. In fact, at T = 183 °C alcohols are the main product of alkene hydroformylation in a process called hydroxymethylation 10a. Alcohol formation is normally assumed 7,99 to result from further reaction of the aldehyde formed in step e with the catalyst HCo(CO) 3 to form a hydroxyalkyl complex which can react with H 2 to eliminate the alcohol and regenerate the catalyst HCo(CO) 3 …”
Section: Oxidative Addition Of H2 and Aldehyde Reductive
Eliminationmentioning
“…The authors showed that the C 2 v structure was more stable than the D 3 h one by 22.3 kJ mol -1 , in agreement with experimental data and preliminary EHT calculations . The calculated enthalpy of hydrogenation for the C 2 v species of 27.4 kJ mol -1 is close to the two available experimental values of 19.7 and 16.9 kJ mol -1 and agrees with the experimental observation that Co 2 (CO) 8 is readily converted to HCo(CO) 4 10a…”
Section: Generation Of the Active Speciessupporting
confidence: 88%
“…Due to the importance of this process, the study of its mechanism has always given rise considerable interest from both experimental and theoretical points of view. ,, The most widely accepted mechanism for the hydroformylation reaction of eq 1 catalyzed by HCo(CO) 4 is due to Heck and Breslow and involves five steps (see Scheme ). The same basic steps, but with the implication of a binuclear cobalt species in the last step of the mechanism, have been proposed by Orchin. 10a,c Likewise, the mechanism proposed by Wilkinson et al for the catalytic cycle mediated by HRh(CO) 2 (PPh 3 ) 2 consists of the same five steps: (i) ligand dissociation, (ii) olefin coordination, (iii) olefin insertion and PPh 3 addition, (iv) CO insertion, and (v) H 2 oxidative addition and aldehyde reductive elimination. 1 Heck and Breslow Mechanistic Proposal for the Hydroformylation Process…”
Section: Organometallic Reactions Involving Co or Co2mentioning
confidence: 53%
“…Hydroformylation allows the functionalization of CC bonds, and consequently it can be seen as an efficient synthetic route for the preparation of fine chemicals. It involves low-valent cobalt , and rhodium , complexes as catalysts, although other metals such as platinum, ruthenium, iridium, and palladium have also been employed, especially in the field of asymmetric hydroformylation . The overall equation for the formation of aldehydes from alkenes, dihydrogen, and carbon monoxide can be written as …”
Section: Organometallic Reactions Involving Co or Co2mentioning
confidence: 99%
“…Aldehydes react with HCo(CO) 4 to yield alcohols. , This is a side reaction in industrial catalytic processes. In fact, at T = 183 °C alcohols are the main product of alkene hydroformylation in a process called hydroxymethylation 10a. Alcohol formation is normally assumed 7,99 to result from further reaction of the aldehyde formed in step e with the catalyst HCo(CO) 3 to form a hydroxyalkyl complex which can react with H 2 to eliminate the alcohol and regenerate the catalyst HCo(CO) 3 …”
Section: Oxidative Addition Of H2 and Aldehyde Reductive
Eliminationmentioning
“…[CA] t ϭ 0.287 Ϫ 0.0227t 0.5 (13) [HCA] t ϭ Ϫ 0.008 ϩ 0.0164t 0.5 (14) [STY] t ϭ 0.004 ϩ 0.0063t 0.5 (15) average r 2 ϭ 0.967 equations for Expt. 8 can be seen in Figure 3.…”
The reaction of HCo(CO) 4 (HT) or DCo(CO) 4 (DT) with excess cinnamaldehyde (CA) in methylcyclohexane (RH) at 22.2°and under 1 atm of CO follows pseudo-first-order kinetics in HT or DT with an inverse isotopic effect of 0.54. Identified products of the reaction are hydrocinnamaldehyde (HCA) and styrene (STY). The STY is believed to be an artifact of the thermal decomposition of the true product PhCH 2 CH 2 C( ϭ O)Co(CO) 4 (X) or its isomer. Reduction of the carbon-carbon double bond in CA is effected by hydrogen from both the cobalt compound and RH. It is proposed that the reaction involves a free-radical chain mechanism in which the rate of the slow step is proportional to [CA] 0 n , the initial molar concentration of CA raised to a power of 1.5 -1.8. Additionally the rate of conversion of CA to HCA and X meets the criteria of a homocompetitive reaction with [CA], [HCA], and [STY] simple functions of t 0.5 (where t is reaction time) for use of DT or (in a single case) a function of (t 0.5 ϩ t) for use of HT.
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