As an acetylation agent accompanied with antioxidative action, reactiveness of thioacetic acid with alcohol has been investigated. Since it has been said that only the secondary alcohol forms a regular ester, isopropyl alcohol was chosen as a sample and the effects of using of catalysts, its molar ratios, the temperature and time of reaction have been investigated. In case of using of no catalyst, the reaction was extremely slow as reported by F. B. Stewart, et al. The effective catalyst for this reaction was not basic substance but it found to be an acidic substance. Sulfuric acid showed a remarkable effect on the reaction at different temperatures and molar ratio of thioacetic acid and alcohol but hydrochloric acid showed no great change in results. In case of using sulfuric acid as the catalyst, the reaction was stopped at about 70% yieldof the ester regarless of the time of reaction. However, thioacetic acid is considered to be useful as an acetylating agent, especially for unstable compounds, from the reductive property of H2S given off.
Reactiveness of thioacetic acid with phenol has been investigated.β-Naphthol was used as a sample and the effects of using of catalyst, the temperature and time of reaction have been investigated. The reaction was extremely slow without catalyst as in the case of using alcohol. The acid as catalyst was entirely unsatisfactory while the basic substance (pyridine) was found to be effective, contrary to the case of using alcohol. The temperature had a marked effect and the reaction was proceeded smoothly with the elapse of time. The yield was above 90% under boiling condition for a comparatively short time. Although the amount of catalyst had less effect in case of reaction at high temperature but the reaction was accelerated by increasing the catalyst at low temperature. The amount of thioacetic acid showed a mutual effect of reaction at high temperature and with more catalyst and the reaction was almost quantitative.
An addition reaction of various reagents on a double bond of vinyl acetal (1, 1-dialkoxy-3-butene) has been investigated.(1) The addition of hydrogen halides was proceeded without catalyst and at room temperature towards the direction of Markownikoff's rule. The product was β-halobutyraldehyde acetal. The anti-Markownikoff type additive reaction by use of HBr was not successful due to predominance of ionic reaction.(2) Addition of halogen was proceeded smoothly at low temperature but the distillation of product was difficult, probably due to the presence of unstable side-reaction product.(3) Alcohol gave 1, 1, 3-trialkoxybutane by addition in the presence of hydrochloric acid catalyst.(4) Mercaptan gave an addition product composed of 4-alkylmercapto-butyraldehyde acetal with high yield by exposure to ultraviolet light or in the presence of mercuric oxide catalyst. In the presence of hydrochloric acid catalyst, a 3-substituted product was formed by Markownikoff type additive reaction.
The behaviors of the oxo-reaction of vinyl acetal, the dealcoholization and the reaction with ammonia have been investigated.(1) In the oxo-reaction, the aldehyde group was introduced at the terminal of the chain to give a product having a skeleton of glutaraldehyde but the product was not in a pure form as it was accompanied with cyclization and disproportionation Acetalization treatment for simplification of this procedure gave glutaraldehyde bisacetal as a main product or the cyclization gave 2, 6-dialkoxytetrahydropyran as amain product.(2) The vapor phase dealcoholization reaction from use of BaO-SiO2 catalyst caused the liberation of one molecule of alcohol and gave 1-alkoxybutadiene with high yield.(3) The reaction with ammonia in the presence of aqueous ammonia rammonium acetate catalyst or anhydrous ammonia Nieuwland catalyst (Cu2Cl2-NH4Cl) gave 2-methyl-5-ethylpyridine.
The rates of epoxidation of cis-and trans-α, α′-dimethylstilbene and 4, 4′-dimethoxy, 4, 4′-dimethyl, 4, 4′-dichloro, 4, 4′-dibromo, and 4, 4′-dinitro-derivatives with perbenzoic acid in benzene were determined at three temperatures, and the energies, free energies, and entropies of activation calculated. Values of the entropy of activation were nearly the same for all the cis-compounds and this was also the case for all the trans-compounds. The electron releasing substitueuts decreased and the electron attracting substituents increased, the free energy of activation. The Hammett treatment of the substituent effect gave an excellent straight line with the exception of the points for 4, 4′-dimethoxy derivatives in both cis- and trans-series. The difference in reactivity towards perbenzoic acid between cis-and trans-isomers was discussed.
The rates of epoxidation of trans-3, 3′-dimethyl, trans-3, 3′-dimethoxy, cisand trans-3, 3′-dibromo, cis- and trans-3, 3′-dinitro-α, α′-dimethylstilbene with perbenzoic acid in benzene were determined at three temperatures, and the energies, free energies, and entropies of activation calculated. Values of the entropy of activation were nearly the same for all cis-compounds and this was also the case for all the trans-compounds. The electron releasing groups decreased, and the electron attracting groups increased, the free energy of activation. The Hammett treatment of the substituent effect gave an excellent straight line with the exception of the point for trans-3, 3′-dimethoxy derivative for both cis- and trans-series. The Hammett line for the meta derivatives fell in a lower position than that for the para derivatives.
The rates of epoxidation of trans-4-brom-, trans-4-methoxy-4′-nitro-, trans-4-methyl-4′-nitro-, and trans-4-chloro-4′-nitro-cc, c′-dimethystilbene with perbenzoic acid in benzene were measured at three temperatures, and the energies, free energies, and entropies of activation calculated. Including the results of previous papers, general discussion was presented. Values of the entropy of activation were nearly the same for all the cis-compounds and this was also the case for all the trans-compounds. The substituent effect shows that the dimethylstilbenes behave as nucleophilic and perbenzoic acid as electrophilic reagent. There was satisfactory linear relation between the rate constants and the sum of the Hammett's “sigma” constants for the two substituents for both cis- and trans-series, respectively. Vurther, r-values for cis- and transseries calculated -from the Yukawa's equation were compared with each other, and the difference between them was discussed. The rates of the epoxidation of trans-stilbene and trans-ct-methylstilbene were also measured, and the effect of methyl group in the a-position of stilbene was discussed in terms of the steric and inductive effects.