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Страница 87.

Oxidation of the sugar with sodium metaperiodate in the presence of sodium hydrogen carbonate gave 0. 04 mol. of formaldehyde. Hydrolysis of the diketo-ester (II; R = Me) with 5% alcoholic potassium hydroxide gave the diketo-acid (II; R = H), but treatment with 10% aqueous sodium hydroxide led to a phenolic acid. When this procedure failed to provide crystalline sulphone, the mixture was decomposed by ice and dilute hydrochloric acid, and the ethylene dichloride layer was separated and dried after being washed successively with water, dilute sodium hydroxide solution, and water again.
In control experiment, treatment of e-galactan with N-sulphuric acid at room temperature for 30 min. afforded no detectable reducing sugars. However, Kulkarni and co-workers obtained mixtures of cis- and trans-3, 4-diols on reduction of dihydrofisetin and dihydro 4'-methoxy-6-methylflavonol by lithium aluminium hydride. Bognar and Rakosi found that the reduction of dihydroflavonol by hydrogen over a supported palladium catalyst gives the trans-3,4-diol in
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both solvents. Reduction of the derived methyl ester methyl glycosides with potassium horohydride, followed by hydrolysis, gave galactose only. Oxidation of the disaccharide with periodate gave only traces of formaldehyde, whereas oxidation of the acidic disaccharide alcohol (from reduction by borohydride) gave 0,85 mol. of formaldehyde, a result consistent only with the presence of a 1,5-or 1,6-linkage. Conversion into the methyl ester methyl glycosides, reduction with potassium borohydride, and hydrolysis gave arabirio-se and galactose (chromatography). Similar treatment of the disaccharide alcohol (from reduction by potassium borohydride) gave only arabinose. Aliquot (arabinose) were withdrawn at intervals, excess of periodate was destroyed by ethylene and the liberated acid was titrated with 0,015 N-sodium hydroxide. The ether was removed and replaced by xylene, and the solution heated at 90° overnight. In contrast to the rapid reaction of these anilides, the quinoxalines (VI a-d) and the pyrazine (VII) were all unchanged by concentrated sulphuric acid at room temperature. In pyridine solution the 5'-hydroxyl group was phosphorylated by P1P2-dibenzyl P1P2-diphenyl pyrophosphate, tetra-allyl pyrophosphate, and tetrabenzyl pyrophosphate in that order of reactivity. The normal wave-guide connected to the heat-break was warmed by a small heater, to prevent condensation of moisture.
§ 140. Нередко вместо предлогов by и with употребляется сочетание by means of.
Например:
The magnetic field was measured by means of a marginal oscillator proton resonance meter.
The second harmonic of the frequency of the resonance was measured by means of a T74 frequency meter, manufactured by Telemechanics Ltd.
The values of «g» were calculated directly, the microwave frequency being measured by means of a Philips wavemeter, type RP4290X.
Exinite and micrinite, which are richer and poorer respectively than vitrinite in hydrogen, differ in density and can be fracti-oned, though with difficulty, by means of liquids differing in specific gravity.
§ 141. Следует также отметить, что предлог by входит в состав некоторых глагольных сочетаний и отвечает на вопросы: кем. чем. (например: to be followed by, to be accompanied by, to be provided by, to be substituted by, to be affected by, и т. п. ). Например:
То, что за раскрытием эпоксидного кольца не следует перемещение брома к алкоксидному кислороду, не является
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неожиданностью. «That opening of the epoxide ring is not followed by displacement of the bromine by the alkoxide oxygen is not surprising*.
Реакция сопровождалась бурным выделением тепла. «The reaction was accompanied by violent evolution of heat».
Водородные атомы СН2-групп замещаются углеводородной группой обычным способом.

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