Hydrolysis of benzyl chloride

Table V. Hydrolysis of Benzyl Chloride in Sediment/Water Systems at 25°C...

When treating the overall transformation kinetics of an organic compound as we have done for the hydrolysis of benzyl chloride (Eq. 12-11), we assume that the reverse reaction (i.e., the formation of benzyl chloride from benzyl alcohol) can be neglected. For many of the reactions discussed in the following chapters we will make this assumption either because the reverse reaction has an extremely small rate constant (i.e., the reaction is practically irreversible), or because the concentration ) of the reactant(s) are very large as compared to the concentration(s) of the product(s). There are, however, situations in which the reverse reaction has to be taken into account. We have already encountered such a reaction in Illustrative Example 12.1. To demonstrate how to handle the reaction kinetics in such a case, we use the hydration of an aldehyde to yield a diol (Fig. 12.3). This example will also illustrate how the equilibrium reaction constant, Kn is related to the kinetic rate constants, kY and k2, of the forward and reverse reaction. 

Benzyl Alcohol Phenylmethanol or Hydroxytol-uene (called l -Oxy-T-methyl-benzol and benzyl chloride with Na or K carbonate in soln or by other methods. There are two commercial products technical grade and "FFC (free from chlorine) grade(Ref 3). Toxicity and fire hazard are discussed in Ref 5. It is used extensively in many branches of the chem industries, such as, for the manuf of esters(acetic, benzoic, sebacic, etc), as a solvent for cellulose esters ethers, etc. During WW I, it was used in a "dope for airplane fabrics... 

Benzyl alcohol is manufactured by hydrolysis of benzyl chloride. 

Analogous uncertainties apply to the analysis of the dependence of rate constant on pressure. Golinkin et al. (1966) discuss the various equations used to describe this dependence in the context of the hydrolysis of benzyl chloride in aqueous mixtures. 

The exciting suggestion that AH for the hydrolysis of benzyl chloride is negative at temperatures below 277 K (Hills and Viana, 1971) turned out to be incorrect (Albery and Curran, 1972). The more recent proposal that in the hydrolysis of t-butyl chloride there is an induction period which depends on the hydrogen ion concentration (Adams et al., 1973) is puzzling. The possibility that these observations arise from practical problems associated with the low solubility of t-butyl chloride in water warrants consideration. 

With reference to the dependence on co-solvent of the kinetics of one reaction, the hydrolysis of benzyl chloride (Golinkin and Hyne,... 

The dependence of volumes of activation, AV, on solvent composition for the hydrolysis of benzyl chloride in aqueous mixtures (Golinkin et al., 1966 Hyne et al., 1966) has been analysed using the solvent dependence of the partial molar volume of the initial state (Golinkin et al., 1967). In aqueous alcohols, as x2 increases, AV decreases to a minimum value at a mole fraction characteristic of the alcohol, e.g. x2 =0-1 for t-butyl alcohol, the intensity of the extremum increasing on going from methyl alcohol to t-butyl alcohol. The dependence of AV on x2 is a consequence of quite marked changes in the quantities 5m Vf and 8m V (Dickson and Hyne, 1971). For example, in ethyl alcohol + water mixtures, 5m V for benzyl chloride in the initial state has a maximum near x2 = 0-3, whereas 5m V has a shallow minimum near x2 = 0-1 (cf. V2 for Me4N+Cl- in these mixtures Lee and Hyne,... 

The rate constant for the hydrolysis of t-butyl chloride at 298 K decreases as x2 increases in DMSO + water mixtures (Heinonen and Tommila, 1965). A clear-cut contrast between TA and TNAN mixtures is shown by the volumes of activation and related parameters for the solvolysis of benzyl chloride in acetone + water (TA) and DMSO + water mixtures (Fig. 57). Thus, in the latter system, the curves show no marked extrema but there is a shallow minimum in AV near x2 = 0 4. Extrema in Sm AH and T. 5m AS for the hydrolysis of benzyl chloride are also smoothed out when the co-solvent is changed from acetone to DMSO (Tommila, 1966). A similar trend is observed in the kinetic parameters for the hydrolysis of chloromethyl and methyl trifluoroacetates (Cleve, 1972a). For example, in the case of the chloro derivative, 6mACp decreases gradually over the range 0 < x2 < 0-2 for DMSO + water mixtures, whereas a minimum is observed in this range for acetone + water mixtures. 

In the hydrolysis of benzyl chloride, the leaving group is chloride anion. When benzyl fluoride is hydrolyzed in alkaline or neutral media, the leaving group is fluoride anion, which is a worse leaving group than chloride anion because the carbon-fluorine bond is much stronger than the carbon-chlorine bond 443 kJ (106 kcal/mol) vs. 328 kJ (78 kcal/ mol), respectively. 

Derivation (a) By hydrolysis of benzyl chloride (b) from benzaldehyde by catalytic reduction or Cannizzaro reaction. 

Yadav, G. D., and P. H. Mehta, Theoretical and Experimental Analysis of Capsule Membrane Phase Transfer Catalysis Selective Alkaline Hydrolysis of Benzyl Chloride to Benzyl Alcohol, Catal. Lett., 21, 391 (1993). 

Allyl chloride, crotyl chloride, and 1,3-dichloropropane show bimolecu-lar reactions with water and are 8x2 reactions. The effect of solvent is shown by the hydrolysis of benzyl chloride which is bimolecular in 50 per cent aqueous acetone and almost unimolecular in water. The formation of ethylene oxide from ethylene chlorohydrin is a reversible reaction ... 

Benzaldehyde can also be synthesized by the oxidation of toluene or by the hydrolysis of benzyl chloride in the presence of an alkali. 

Hydrolysis of benzyl chloride with water in microwave oven gives 97% yield of benzyl alcohol in 3 min (Scheme 2). The usual hydrolysis in normal way takes about 35 min. 

The hydrolysis of benzyl chloride is catalyzed by the presence of Hg" salts. The electrophilic salts are here behaving as acids and react with the organic halide to form a carbonium ion ... 

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