1062 (s), 998, 973 (s), 956 (s), and 902 (s) cm-1; nmr (CHCla) 6 3.9 (br s, 2 H), 3.5 (br unresolved m, 2 H), 2.0 (m, 5 H), and 1.61 (br s, 7 H). A sample of 10 was prepared according to the directions of Appleton, et aZ.,* and spectral comparison showed it to be idenlical with the 5% diol above.The 2% component (11) was not isolated in pure form, being contaminated with stopcock grease and traces of alumina. This crude material (84 mg) was stirred at 25' with 75 ml of 0.0125 M potassium periodate solution and 7.5 ml of 2.0 N sulfuric acid for 24 hr. Titration according to the directions given by Jacksonz4 showed that periodate equivalent to 17.4 mg of diol was consumed.The 46% component (9) was isolated as a crystalline solid and was purified by sublimation: mp 118-121"; ir (KBr) 3320, 1150 (w), 1074, 1052 (s), 1034, 1008 (s), 996, 906, and 720 cm-l; ir (CClr) 2930, 2872, 2856, 1468, and 1466 cm-'; nmr (CHCla) 6 4.05 (br s, 2 H), 3.49 (m, 2 H), 2.16 (m), 1.93 (br s), 1.58 (br s), and 1.0-2.4 (12 H). A sample (118 mg, 0.76 mmol) of this diol was oxidized with periodate as described above. In 24 hr a t 26", ll3Y0 of the theoretical amount of periodate was consumed. The reaction mixture was concentrated in vacuo, saturated with sodium chloride, and extracted with chloroform. The extracts were dried (MgSOI) and the solvent was evaporated to give 130 mg of solid, mp 154-156', which reacted with dinitrophenylhydrazine and showed bands in the infrared at 2710 and 2810 cm-1. Treatment of the crude material with 30% hydrogen peroxide gave a crystalline acid, mp 153-155' (lit.16 mp 150-152').Enol Fraction.-Glpc examination of the enol fraction showed three components. The major component (23% of the solvolysis product or 50y0 of the enol fraction) was shown by glpc compari-(24) E. L. Jackson, Ow. Reactions, 2, 341 (1944). son (12 ft x 0.125 in. 5% FFAP column at 145') to be identical with the main component of the trifluoroacetolysis, L e . , 3 + 4.The minor component (3% of the solvolysis product or 6% of the enol fraction) was not isolated, but was shown by glpc comparison to be different from the hydride reduction products of either 5 or 6.A sample of the enol fraction (110 mg) was hydrogenated over palladium on charcoal in methanol solution. The main product was collected from a preparative gas chromatographic run: mp 176-178'; ir 3400, 2980, 1480, 1040, 982, 963, and 910 cm-1. The spectral data and melting point identify this as 2.Partial separation of the two main enol components was achieved in a preparative scale gas chromatography run on 5 ft X 0.25 in. 20% SE-30 on Chromosorb W column at 90". A crude sample enriched in component 7 (21% of the solvolysis mixture) was obtained: mp 127-131'; ir (CC11) 3620, 3360 (br), (m), and 985 cm-l (s); nmr (CClr) 6 5.5-6.0 (m, 2 H), 3.82 (unresolved, 1 H), 2.23 (m), 2.08 (s, 1 H), 2.0 (m), 1.5 (br s), and 1.2-2.4 (11 H). Compound 7 is reported" to melt a t 103-103.5', but the overlap between the peaks for enols 3 + 4 and 7, even on an analytical level, prevented isolation of p...
The yields and purity of the crude disulfides were determined by weight and analytical method^.^^' Their disulfide and thiol contents were determined and the results are shown in Table I, along with melting points of the crude and purified disulfides.Oxidation of Benzenethio1.-Two-tenths of a mole of benzenethiol was dissolved in 100 ml. of dimethyl sulfoxide and the solution was maintained a t 85 f l o . Samples were removed a t various intervals and analyzed for thiol and disulfide content.617The following conversions of thiol to disulfide were found: 85Y0 after 30 min., 92.47, after 1 hr., 96.77, after 2 hr., 98.3% after 4 hr., and 98.9y0 after 6 hr.Oxidation of Benzenethiol in the Absence of Air .-A 250-ml. three-necked flask was equipped with a magnetic stirrer, thermometer, a nitrogen gas inlet tube, and an outlet to a trap cooled in Dry Ice. The flask was charged with 11 g. (0.1 mole) of benzenethiol and 50 ml. of dimethyl sulfoxide under a blanket of nitrogen and the solution was heated with stirring a t 80" for 18 hr. with a continuous flow of nitrogen through the system. The disulfide isolated in almost theoretical yield by procedure A weighed 10.8 g. and melted a t 61-62",The liquid condensed in the Dry Ice trap separated in two layers. The upper one proved to be the expected dimethyl sulfide by infrared spectrum and boiling point; the lower layer was mainly water.Similar results were obtained when the experiment was carried out with a-toluenethiol with the by-products being identified as dimethyl sulfide and water. The disulfide was obtained in 88% yield with m.p. 71-72".
Der Ablauf der Lactonisierung bei Camphen‐8‐carbonsäure (II) wird wesentlich durch die Reaktionsbedingungen bestimmt.
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