No abstract

Contribution to the study of the behaviour of catechin in alkaline medium SummaryWhen catechin (1) is warmed with aqueous alkali it first undergoes rapid epimerisation. After some time a novel bridged carbocyclic enol, catechinic acid (3) separates out and may be isolated in excellent yield. Eventually catechinic acid isomerises to 2-(3', 4'-dihydroxyphenyl)-3,9-epoxy-6-oxo-bicyclo[3,3,l]-non-7-en-8,9diol (4) via an open chain anion (5) which is also involved in the epimerisation of catechin. Assignments of structure are given and the equilibria observed are discussed. En 1830, Nees von Esenbeck [I] a montrt qu'un extrait vCgCtal, le catechu, dont le constituant principal est la cattchine, applelCe Cgalement cyanidanol-3, devient brun-rouge foncC dans une solution aqueuse de carbonate de potassium. Plus tard, Freudenberg et al. [2-41 ont trouvk qu'en milieu aqueux faiblement alcalin, la (+)catkchine ( l a ) est tpimkrisee en (+)-kpicattchine ( l b ) et la (-)-catkchine ( l c ) en ( -)-CpicatCchine (1 a). OH OH l a 2 R , 3 S l b 2 S , 3 S l c 2 S , 3 R I d 2 R , 3 R Metha & Whalley [ 5 ] ont proposC que la catichine s'epimbrise par ouverture et fermeture de la liaison 0(1)-C(2) avec la participation de l'ion phCnate en position 4', form6 en milieu alcalin. En effet, ils ont montrC que la O-tCtramCthyl-5,7,3', 4'-(+)-catCchine, dans laquelle il ne peut pas se former de phCnate en 4', ne s'CpimCrise pas. 122,O (d) 131,8 (s) 144,1 (s) 144,6 (s) 191,5 (s) 193,l (s) 212,2 (s) 36,7 ( t ) 53,6 id) 579 (dl 653 (4 6 6 3 (4 106,4 (d) 117,l (d) 117,2 (d) 121,9 (d) 131,6 (s) 144,2 (s) 144,7 (s) 190,6 (s) 192,5 (s) 211,4 (s) a) Multiplicitt du spectre partiellement dtcouple.

In schwach alkalischem Medium erfolgt Epimerisierung von (+)‐Catechin (Ia) zu (+)‐Epicatechin (Ib) und von (‐)‐ Catechin (Ic) zu (‐)‐Epicatechin (Id).

The adsorption of a water-soluble surface-active agent at the solution/air interface has been measured by taking advantage of the soft beta-radiation from the radioactive isotope of sulphur, 35 S. The method depends upon the fact that, because of 'self-absorption ’ of the radiation by the solution, and because the molecules of a surface-active agent are preferentially adsorbed at the interface, the radioactivity above a solution containing such an agent labelled with radiosulphur should be higher than that from a solution (e. g., of sodium sulphate) in which no surface adsorption occurs. Carefully purified di- n -octyl sodium sulphosuccinate and sodium sulphate were each synthesized with 35 S. Measurements on solutions of these showed that the radiotracer technique permitted a successful quantitative determination of the adsorption. Counting rates over the solutions of agent were 1.1 to 20 times those of the corresponding sodium sulphate, and for some 29 different solutions covering a range of specific activities (1 x 10 12 to 5 x 10 9 ) counts/min./mol.) and of concentrations (0.1 to 150 x 10 -8 mol./ml.) a well-defined adsorption isotherm resulted. The surface excess obtained from the tracer measurements agreed with that calculated from surface-tension measurements by the Gibbs equation if it was assumed that no Na + and only H + were associated with the long-chain ions adsorbed in the interface. The radioactivity measurements suggested further that, after the agent had formed a uni-molecular layer, a further increase in bulk concentration caused further adsorption at the interface. An interesting aspect is that the rate of adsorption was followed in the low concentration ranges. The method promises to be useful for studying the kinetics of such adsorption processes. The radiotracer method outlined above seems to be generally applicable to surface phenomena involving adsorbed layers, either mono- or multimolecular in nature. Although this paper describes the use of 35 S, it is evident that other radioisotopes having sufficiently soft radiation, such as 14 C, 45 Ca, 59 Fe, etc., could be employed. Moreover, the method appears to open considerable possibility for examining interaction in surface layers.

THE JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY 831 for anaesthetic purposes should comply with the following requirements:1. Boiling Point.-Ethyl chloride should possess a boiling point of +12.5°C .2. Odor.-On allowing 30 cc. of ethyl chloride to evaporate from a filter paper 1 21 /2 cm. in diameter, no foreign or unpleasant odor, especially a garlic odor (indicating phosphorus compounds), should be apparent either during or subsequent to evaporation.3. Residue.-When 60 cc. of ethyl chloride are allowed to evaporate in a platinum dish at room temperature. there should be left no weighable residue.4. Alcohol.When 10 cc.of ethyl chloride are agitated with 10 cc. of distilled water, both of which are at about 10o C., in a glass stoppered tube, and the supernatant layer of ethyl chloride is allowed to evaporate spontaneously from the opened tube at room temperature, and then 3 drops of potassium dichromate T. S. are added to the remaining water, followed by 5 drops of dilute sulfuric acid, and the mixture is then boiled, no odor of acetaldehyde should be apparent and no greenish or bluish color should be produced in the liquid. j. Hydrochloric Acid and Metallic Chlorides.-On dissolving 10 cc. of ethyl chloride in 10 cc. of 95 per cent alcohol U. S. P., and then adding 3 drops of silver nitrate T. S., no turbidity, even faint, should result, and no precipitate should form.A simple combination test for the purity of ethyl chloride consists in attaching a 30 cc. ethyl chloride container to a glass tube vial containing 35 cc. of water kept at 40°C . A slow stream of ethyl chloride is passed through the water until the container is emptied, and then 10 cc. of the water are tested with litmus paper, to which it should impart no acid reaction; 10 cc. with silver nitrate T. S.. as in test 5 above; and 10 cc. are finally tested for alcohol as in test 4 above.