The Phenolysis of Tetrahydrolinalyl and 2-Octyl Systems. The Rates, Steric Courses, and Product Distributions
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概要
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As tertiary and secondary systems with optical activity, tetrahydrolinalyl (methylethylisohexylcarbinyl) chloride or <I>p</I>-nitrobenzoate and 2-octyl <I>p</I>-toluenesulfonate have been selected, and their titrimetric and polarimetric rate constants (<I>k<SUB>t</SUB></I> and <I>k<SUB>p</SUB></I>) for <I>S</I><SUB>N</SUB>1 phenolyses have been measured in the presence of triethylamine (or sodium phenoxide) in 50 wt% phenol–benzene. At higher amine (or phenoxide) concentrations, the <I>k<SUB>t</SUB></I> and <I>k<SUB>p</SUB></I> coincide with each other for tetrahydrolinalyl chloride (at 25.0°C) or <I>p</I>-nitrobenzoate (at 100.0°C), and also for 2-octyl tosylate (at 75.0°C), exhibiting the typical features of the <I>n</I><SUB>N</SUB>1 solvolysis rate constant. In the absence of the amine (or sodium phenoxide), the <I>k<SUB>t</SUB></I> diminishes to show a gap between the <I>k<SUB>p</SUB></I> and the <I>k<SUB>t</SUB></I>, indicating the occurrence of an ion-pair return in the phenolysis for both systems. Under the same reaction conditions as those of the rate measurement, tetrahydrolinalyl chloride and <I>p</I>-nitrobenzoate yield the phenyl ether, with a predominant racemization accompanied by some net inversion of the configuration, whereas 2-octyl tosylate gives 2-octyl phenyl ether, <I>o</I>-, and <I>p</I>-2-octylphenols, with a net inversion of the configuration accompanied by a slight racemization. These steric results indicate that phenol can be considered as a typical solvolytic solvent. The product distributions have been assessed for the reactions of 2-octyl chloride (200°C) and of tetrahydrolinalyl chloride (25.0°C) with the molecule of phenol under the <I>S</I><SUB>N</SUB>1 phenolysis conditions, by extrapolating the product composition curves to a zero concentration of the phenoxide. For both systems, the phenol molecule is predominantly <I>O</I>-alkylated (74 and 99% respectively), accompanied by minor amounts of <I>C</I>-alkylation. In contrast to the phenol reaction, the phenoxide ion undergoes more <I>C</I>-alkylation (42 and 50% respectively).
- 公益社団法人 日本化学会の論文
著者
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KINOSHITA Tomomi
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University
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Okamoto Kunio
Department of Fuel Chemistry Faculty of Engineering Kyoto University
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