2972
NOTES
1701. 61
yield, 2.12 g. (38%) of white crystalline powder, rn. p 245.5-247.5" ( ~ o r r . ) . ~With Grote's reagent6 a faint orange color developed only after addition of potassium cyanide, as is characteristic of monosulfides. Anel. Calcd. for Cl~HaoC&N&:S, 10.53; C1, 23.33. Found: S, 10.24; C1, 23.31, 23.36.
supposedly pure substances of the mannose series might be compounds of this nature, an hypothesis which easily could account for the exceptional rotations. Many efforts by various ways to separate a-methyl manpopyranoside into components bis-(&DiethyIaminoetbythyl) sulfide dihydmbromide was and similar experiments on its tetraacetate and on prepared similarly to the dihydrwhlotide as a white the tetraacetate of b-methyl mannopyranoside, crystalline powder, 111. p. 237.3-237.8O (corr.). led to negative results; the hypothesis of the comAmZ. Calcd. for ClzHsOBr&S: Br, 40.56. Found: pound nature of any of these substances thus beBr, 41.06. came very improbable but nevertheless the fail(4) W. E. Lawson and E. E Reid, THISJOURNAL, 67,2821 (1925). ures did not eliminate it as a possibility. Posigive 247' (corr.) as the melting point of the compound prepared from tive proof that they are true chemical individuals, ,9, pY-dichlorodiethyl s a d e and diethylamine. (6) I. W. Grote, J. Bid. C h e m , 93, 25 (1931) not molecular compounds, was obtained in the RESEARCH LABORATORIBS course of experiments6on the oxidation of methyl INSTITUTUM DIVIT ~ O M A E RECEIVED Jtm 14, 1939 glycosides by periodic acid; their exceptional roCINCINNATI, OHIO tations, as compared with those of their glucose analogs, are not attributable either to ring-size or Relations between Rotatory Power and Structo any lack of chemical individuality. As was ture in the Sugar Group. XXXIV. The Pospointed out some years ago,' there are several rent Conformations of the differences of rotation in the mannose pyranoid Pyranoid Ring' series that conform closely with analogous differBY C. S. HUDSON ences in the glucose series, provided one compares In a preceding article by Eugene Pacsu2 he substances of a-classification only, or of 8-classisuggests that the exceptional character of the ro- fication only. Pacsu now iinds similar relationtations of the a-and b-forms of substances having ships in the fructose and sorbose pyranoid series. the pyranoid ring structure in the mannose series It would seem therefore that the agreement of romay be due to a difference in the conformation of tational differences within the a- or the b-series, the atoms forming the ring. I thank Dr. Pacsu, when coupled with the known disagreement auoss with whom I have conferred often during the prog- an a-/!? pair, probably indicates differences in pyress of his research, for this opportunity to pub- ranoid ring conformation. (6) Jackson and Hudson, ibid., 61, 969 (1939). lish concurrently thc reasons which have led me (7) Hudson, ibid., 48, 1424 (1926). to take the same viewpoint on this question. CONTRIBUTION FROM THE In 19303 I expressed the view that the excep- NATIONAL INSTITUTE OF HEALTH HEALTH SERVICE tional character of these rotations indicated that U. S. PUBLIC WASHINGTON, D. C. RECEIVED AUGUST11, 1939 the substances had different ring structures, and 1 assumed that the a-forms were of the furanoid and the @-formsof the pyranoid type. The ex- The Reparation of Seleno Ortho- and Metaperiments of Haworth and H i n t 4 and their colCresols laborators, designed to test this view, yielded reBY DUNCAN G. FOSTER sults which showed that it is not tenable and that In preparing a series of compounds for the the substances in question possess only the pymeasurement of vapor-phase absorption spectra ranoid ring. From then on I have searched for it developed that the two compounds seleno oan explanation of these unusual rotations that and m-cresol, CHsCeH*SeH, had never been dewould be compatible with a pyranoid ring strucscribed in the literature. The writer has prepared ture. The discovery6 of a crystalline molecular them by the standard method of treating the tolyl compound of the a- and @-formsof methyl xyloGrignard reagents with elementary selenium, side suggested the possibility that some of the operating in a current of hydrogen. When hydro(1) Publication authorized by the Surgeon General, U. S. Public Health Service. No. XXXIII w a s published in Tars JOURN.&, 81, gen was not used no selenocresols were obtained, 1658 (1939) but only high-boiling selenides, which perhaps (2) Pacsu, Tms JOUKNAL, 61,2669 (1839) 3 ) Hudson, zbzd , Sa, 1 G W (1930) explains why they are not reported. (4) Hnworth and Hirst, J . Chcm. SQC, 2615 (1930). el Seq Hor6ctt slid Hudsou. THXS J O U R ~ A L b9, 4454 (1931).
);,
(1) Tnboury, Aiira. chdnr. Phys , 16, 5 (1908)
Oct., 1939
NOTES
2973
TABLE I Product
Starting
compound
B E P A R A T I O N DETAILS AND ANALYSES Yield Mdz: or b.Gm. Physical form, G. G. % color
,
o-CH&&SeH m-CHsCsHSeH o-CH&HSeO*H
o-CHaCsH4Br m-CHsCeHrBr o-CH8CsH4SeH
85.5 85.5 4.0
35 40 3.3
41 47 72
99 89 123-125
m-CH&eHSeOzH
m-CHsCsH4SeH
7.0
5.7
96
118-119
The compounds are colorless liquids when absolutely pure, but rapidly turn yellow on contact with the air. Direct analyses were found to be impracticable because their acid nature renders the Parr bomb method inapplicable and their instability and toxic properties make handling for carbon and hydrogen determinations difficult. For identification, they were converted to the acids CH3CeH4Se02H2by dissolving in nitric acid and these compounds analyzed for carbon and hydrogen. This does not distinguish them from the ditolyl diselenides, which would behave in the same way, but the boiling points weremuch too low for them to have been diselenides. The copper salts were also prepared by standard means.3 They were blue crystalline solids without m. p.
25 16
Colorless liquid White needles White needles or plates
Analysis Calcd. Found
C 41.38 H 3.94
C H C H
41.03 3.91 41.46 4.07
Sample B-6712, also gave good results. We are not prepared to explain why these are better, but simply state the result of empirical observations and call attention to the importance of this detail. Secondly, we found that in the preparation of pectic (polygalacturonic) acid, it was quite necessary for the best yield to remove the last trace of the calcium chloride which we used for controlling the swelling of the pectin. This was accomplished as follows. After swelling the pectin in alcohol and calcium chloride, adding sodium hydroxide, acidifying and washing (until no precipitate resulted upon the addition of sodium oxalate or five volumes of alcohol), the resultant pectic acid was suspended again in a volume of water equivalent to that of the alcohol. About half as (2) Pyman, J . Chcm. Soc., [ l ] 116, 166 (1919). much sodium hydroxide was added as before. It (3) Stoecker and Krafft, Bet.., Sg, 2200 (1906). was then acidified and washed again. The pectic CHEMICALLABORATORY acid obtained has no contamination with pectin or SWARTHMORE COLLEGE SWARTHMORE, PENNSYLVANIA RECEIVED JUNE 7, 1939 calcium chloride. That the concentration of calcium chloride affects enzymic action is shown by the fact that addition of calcium chloride to Note on the Preparation of d-Galacturonic Acid the enzyme-pectic acid mixture will inhibit the BY IRAA. MANVILLE, FRANCIS J. REITHELAND PAULM. action of the enzyme. YAMADA Thirdly, we found that of those preparations In a recent article1 there was described a method tried, only Riihm and Haas Pectinase 46 AP for the enzymic preparation of d-galacturonic acid seemed to yield satisfactory results. This is the from polygalacturonic acid. We have had the enzyme contained in the preparation used by pre-publication privilege of using this method for Mottern and Cole. preparing the d-galacturonic acid necessary for Several other minor points should be mentioned. our work on its nutritional significance. It was After enzyme action is complete, we find it advanfound in our laboratory that the method, though tageous to add the sulfuric acid before filtration. far superior to former methods in many respects, Further, it is often wise to work up the sludge gave varying yields. Although this in no way de- from the alcohol precipitation by treating it with tracted from the excellence of the method, it posed small amounts of sulfuric acid and carrying it on in the question as to what factors should be con- the same manner as the original material. By carefully observing all these points in techsidered in improving the yield. First of all we tried different pectins. Of these, nique, we have been able to obtain yields as high there seemed to be considerable variation even as 36% of the theoretical and have had no di0ibetween “batches.” Most satisfactory in our culty in obtaining a very pure product which, work was General Food’s Certo Apple Pectin RX after recrystallization in the p-form from boiling 1 or 2. California Fruit Exchange Citrus Pectin, absolute alcohol, has a melting point of 160’. The purpose of this note is to aid those using ( 1 ) Mottern and Cole, THIS JOURNAL, 61, 2701 (1939).
