Benzyl Alcohol Derivatives Research Articles

Substituent effects in the hydrogenolysis of benzyl alcohol derivatives over palladium

A kinetic study of substituent effects in the liquid-phase hydrogenolysis of benzyl oxygen compounds has been made using carbon-supported palladium as the catalyst. The reaction is zero order in substrate and is progressively inhibited by its product. Proton catalysis is essential for the hydrogenolysis of benzyl alcohols and alkyl benzyl ethers. For the hydrogenolysis of benzyl alcohols and 2-aryl-3-methyl-2-butanols the effects of substituents in the aromatic ring may be expressed in terms of a Hammett-Yukawa relationship with ϱ = −0.37 and −1.43, respectively. α-Substituents retard the rate of hydrogenolysis of benzyl alcohol. The order of reactivity for different leaving groups is: OH, OAlkyl ⪡ OAryl < +OHAlkyl < +OH 2, OAc < OCOCF 3. It is concluded that the hydrogenolysis reaction involves hydride attack at the benzylic carbon displacing the leaving group as its anion. For primary alcohols an S N2 mechanism is operative, whereas tertiary alcohols show s N1 type character. The adsorbed state is discussed on the basis of deuterolysis experiments.

Mechanisms of hydrogenation. Part VI. Configurational inversion in the hydrogenolysis of benzyl alcohol derivatives

The hydrogenolysis: [graphic omitted], (R = H or Me) at palladium, in a non-polar solvent, occurs with inversion of configuration, and the rate of hydrogenolysis increases with the electronegativity of the displaced group X, i.e., X = OH < OAc < OCOCF3.The hydrogenolysis of 1-phenylcycloalkanols: [graphic omitted] n= 4–8, the change of rate with n follows a sequence closely similar to the relative ease of sp3→sp2 change in co-ordination. The rates of hydrogenation of cycloalkanones: [graphic omitted] n= 4–8, follow the converse order, i.e., of ease of sp2→sp3 change in co-ordination with increasing ring size.It is inferred that hydrogenolysis occurs via a metal benzyl complex, e.g., [graphic omitted] PdX formed with retention of configuration, which may add hydrogen with inversion or retention of configuration depending on the metal and the nature of the group X. A previously proposed catalyst model is shown to account for these phenomena.

Studies in organosilicon chemistry. XLII. Reactions of certain silylbenzaldehydes in concentrated base

AbstractA crossed Cannizzaro reaction using formaldehyde with m‐trimethylsilylbenzaldehyde and p‐trimethylsilylbenzaldehyde yields mostly the benzyl alcohol derivative. No formic acid was detectable but a small amount of the substituted benzoic acid was isolated. The corresponding triphenylsilylbenzaldehydes, meta and para, without formaldehyde gave good yields of hexaphenyldisiloxane or triphenylsilanol along with the substituted benzoic acid.

Effect of Acid and Base on the Hydrogenolysis of Benzylalcohol Derivatives

ベンジルアルコール,フェニルベンジルエーテル類,アルキルベンジルエーテル類,ペンジルエステル類および数種のカルボニル化合物をパラジウム炭またはラネーニッケルを触媒として接触還元したときの酸または各種塩基性物質添加の影響を調べた結果,パラジウム炭触媒では少量の酸の添加は水素化分解およびカルボニルの還元を促進し,一方塩基の添加は一般に水素化分解およびカルボニルの還元を抑制した。しかし水素化分解で酸性物質(フェノール類またはカルボン酸類)を生成する場合にはその速度を促進し,ラネーニッケル触媒も水酸化ナトリウムを添加したときは同様であるが,有機塩基では遅くなった。

Intramolecular Interaction between Hydroxyl Group and π-Eelctrons. V. Electronic Effect in Arylcarbinols and a Preliminary Note on the Interaction in Benzylaniline Derivatives

Abstract Absorption due to the O–H stretching vibration in the fundamental region was measured with fourteen benzyl alcohol derivatives to see the electronic effect of the substituent on the interaction between the hydroxyl group and the π-electrons and the following conclusions are deduced. 1) The nature of the interaction or the structure of the molecule which gives rise to the νO–H absorption at 3617 cm−1 is discussed and the interaction between the hydroxyl group and the π-electron on the carbon atom to which hydroxymethyl group is attached (structure III) is favored. 2) The consistency of the wave numbers at which two νO–H absorptions appear, gives further support to the idea that these absorptions originate in the existence of the two rotational isomers. 3) (Remark: Graphics omitted.) is in linear relation with Hammett’s σ values and the σ value of the m-benzyloxyl group is estimated as −0.204. A similar phenomenon is also observed in the substituted benzylanilines.

Pharmacology of Some Saligenin Derivatives

One of the authors reported the remarkable antispasmodic properties of benzyl benzoate and of the benzyl esters for smooth muscle,1 and the local anesthetic properties of benzyl alcohol.2 Numerous attempts were made by different investigators to prepare and study analogous benzyl esters and derivatives of benzyl alcohol, with the object of improving the therapeutic value of the original substances. Thus, Hirschfelder3 pointed out that hydroxy-benzyl alcohol, or saligenin, also produced local anesthesia and was water-soluble. While phenmethylol and saligenin were both potent local anesthetics they had also a mildly relaxant or antispasmodic effect on smooth muscle preparations. Starting with saligenin, we synthesized a series of halogenated and other derivatives, and studied them especially as to their local anesthetic properties and their antispasmodic effects on smooth muscle.The following compounds were prepared: amido saligenin, nitro saligenin, nitroso saligenin, mono-chlor saligenin, di-chlor saligen...