Alcohol formation

Optimum conditions for allylic alcohol formation ( 65% yield of olefin mixture) appear to be those originally described by Wharton, rather than strongly basic forcing conditions. The pyrazole (147) is a by-product. 

Alcohols are the most frequently formed products of ester hydrogenolysis. The hydrogenation of esters to alcohols is a reversible reaction with alcohol formation favored at high pressure, ester at low pressure (/). Copper chromite is usually the catalyst of choice. Details for the preparation of this catalyst (/7) and a detailed procedure for hydrogenation of ethyl adipate to hexamethylene glycol (/[Pg.80]

Nucleophilic Addition of Grignard and Hydride Reagents Alcohol Formation... 

The Claisen condensation of t-butyl acetate with a methyl ester is a general route for the preparation of complex P-ketoesters.4 The reaction requires an excess of the enolate of t-butyl acetate to rapidly deprotonate the product and prevent tertiary alcohol formation. Some workers have also used excess LDA or t-butoxide for this purpose. 

An enzymatic process using partially purified pyruvate decarboxylase (PDC) with added pyruvate overcomes the problems of benzyl alcohol formation and limiting availability of pyruvate [3]. As a result increased concentrations, yields and productivities of PAC were achieved with concentrations of PAC in excess of 50 g f (330 mM) in 28 h and yields on benzaldehyde above 95% theoretical [4-6]. Screening of a wide range of bacteria, yeasts and other fungi as potential sources of stable, high activity PDC for production of PAC confirmed a strain of the yeast Candida utilis as the most suitable source of PDC [7]. 

G. M. Grineva, Alcohol formation and excretion by plant roots under anaerobic-conditions. 5oi Plant Physiology I0 36 (1963). 

The fabrication of colloidal silica and optical glasses by the sol-gel process has attracted a great deal of attention (8). The process relies on the hydrolytic polycondensation reactions of alkoxysilanes, usually (EtO)4Si, in which the reactive silanols (EtO)4 Si(OH)n (n = 1-4) are formed. These then undergo acid- or base-catalyzed condensation with both water and alcohol formation, as shown in Scheme 2. 

The preparation of ketones proceeds conveniently by reaction of imidazolides with organomagnesium reagents, as shown in Table 14-6 for several examples of purely aromatic, aromatic-aliphatic, and purely aliphatic ketones. The yields are very satisfactory even for purely aliphatic ketones, since in this case, too, alcohol formation is completely suppressed.t851,t861... 

One of the main consequences of this change concerns the branching toward the formation of the alcoholate or the release of aldehyde and hydrogenation toward the alkyl intermediate formation. Coordination of the alkali cation weakens the O-C bond, favoring the hydrogenolysis of this bond. Correspondingly, it reduces the chance of alcoholate formation and aldehyde release. This assumption may explain why a2 is only marginally affected by the nature of A (A = Li, Na, K, Cs). 

As normally practiced in a cobalt process, the aldehyde product contains about 10% alcohol, formed by subsequent hydrogenation. Marko (34) reported that the hydrogenation is more sensitive to carbon monoxide partial pressure than is the hydroformylation reaction and, in the region between 32 and 210 atm, is inversely proportional to the square of the partial pressure. The full kinetic expression for alcohol formation is expressed by Eq. (17). 

Dioxygen retards the decay of peracids. For example, kobs = 4.0x 10 6 s 1 in a dioxygen atmosphere and kohs = 1.3 x 10 5 s-1 in an Ar atmosphere (T 345 K, decane, [RSO4H]0 = 9.0 x 10 mol L-1 [25,39]). The decay of peracid is accompanied by the consumption of dioxygen. The ratio of v0/vd> 1 and decreases with an increase in the initial peracid concentration. All these facts prove that peracid decomposes with free radical formation and radicals R formed from the solvent (RH) induce the chain decomposition of peracid with alcohol formation. The decay of peracid to free radicals involves hydrocarbon and bimolecular peracid associates [25,28]. 

Recent work, focused on some mechanistic aspects of this reaction, revisited the fundamental allylic alcohol formation reaction.181 Pyridine easily replaced DME of 118 to give bis(pyridine) complex 120 (Scheme 51). 

Consider a trialkoxysilane as co-precursor for an initial 1 1 mixture of alkoxysilane and organoalkoxysilane, and recall that in the case of ORMOSIL condensation takes place only through elimination of water27 and not by alcohol formation. The mechanism involves hydrolysis and condensation reactions ... 

Methacrylonitrile process, 16 256—257 Methacryloyl chloride, in polyhydric alcohol formation, 2 46 Methacycline, 24 592 Methallyl chloride, production from butylenes, 4 427... 

Houston TE, Mutter LC, Blanke RV, et al. 1981. Chlordecone alcohol formation in the Mongolian gerbil (Meriones Unguiculatus) A model for human metabolism of chlordecone (Kepone). Fundam Appl Toxicol 1(3) 293-298. 

The other reactions of the aldehydes, which are extraordinarily reactive substances, need only he mentioned here. Such reactions are reduction to alcohols, formation of hydrazones, oximes, semicarbazones, bisulphite compounds, acetals and cyanohydrins (by addition of hydrogen cyanide). 

We performed a computational study [69] to assess which interaction (H bonding, metal-alcoholate formation, or metal-alcohol coordination between the allylic hydoxyl moiety and the Re complex) affects the TS and to determine which oxygen of the Re peroxo moiety acts as H-bond acceptor in the case of an H-bonded TS. A summary of the results with propenol as model allylic alchohol is presented in the following. 

Alcohol coordination and metal-alcoholate formation and the corresponding transition structures... 

J. E. Bailie, and G. J. Hutchings, Promotion by sulfur of gold catalysts for crotyl alcohol formation from crytonaldehyde hydrogenation, Chem. Commun. 21, 2151-2152 (1999). 

Biological. Soil water cultures converted l,2-dibromo-3-chloropropane to 1-propanol, bromide, and chloride ions. Precursors to the alcohol formation include allyl chloride and allyl alcohol (Castro and Belser, 1968). 

During oxidation of 4,5-dimethylimidazol by peroxydisulfate in water, the reaction is stopped just at the alcohol-formation step. The alcohol is stabilized due to intramolecular hydrogen bonding. This keeps the alcohol safe from further oxidation (Citterio and Minisci 1982 Scheme 7.51). 

C02(CO)8 SiOj Adsorption from solution and thermal treatment under hydrogen High metal dispersion, small Co clusters favor alcohol formation in the CO hydrogenation [138]... 

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