DEPENDENCE OF OPTICAL ROTATORY POWER ETC. 1699 CLXXVII1.-Studies on the Dependence (4 Optical Rotatory Power on Chemical Constitution. Part IIL I ; 4- Naphthylenebisiminoca~p~or. By BAWA KARTAR SINGH and MAHAN SINGH. THE highest recorded molecular rotation is that of p-phenylene-bisiminocamphor which has [MI, 6173O in pyridine (Forster and Thornley T. 1909 95 ,942). In the present communication is recorded the molecular rotatory power of another similarly constituted compound namely, 1 4-naphthylene bisiminocctmpkor which is endowed with a far higher rotatory power than any compound hitherto known. The marked effect of conjugated linkings on the optical rotation of compounds has already been demonstrated by Rupe (Annulen, 1910 369 311) and Hilditch (T. 1909 95 1570).It is furthe 1600 SINGH AKT) SINGR STUDIES ON THE DEPENDENCE OF ernphasised by the rotation-constants of a series of compounds, similar to the one under discussion described by Forster (Zoc. cit.) and Singh (T. 1919 115 19; this vol. p. 980) and their collaborators. One of the necessary conditions for producing compounds of high molecular rotation appears to bel t o have within a relatively narrow molecular compass the optimum association of unsaturated groups. It is brought out very clearly by counting the number of double linkings in the structural formulae of 1 4-naphthylenebis-iminocamphor y -phenylenebisiminocamphor and 4 4'-diphenylene-bisiminocamphor and comparing the molecular rotatory powers in chloroform : \-/ Nine double linkings. Seven double linkings.Ten double 1inl;ing.s. This illustrates the effect of the optimum association of azethenoid groups conjugated linkings and benzene rings within a given molecular compass. The narrower the molecular compass containing a given number of conjugated linkings the higher is the rotation. Ths effect of solvent on the magnitude of rotation of 1 4-naphthylenebisiminocamphor is remarkable. It is shown in t lie following table r m . Chloro- Methyl Ethyl form. alcohol. alcohol. Pyridine. I 4-Naphthylenebisiminocamphor . . 817ij3 9052' 12071' 13416' p-Phenylenebisiminocanlphor . . . . . . . . 6096 * 6009 5289 61 73 * Difference ........................ 2079 4043 6782 7243 * Forster and l'hornloy (Zoc. cit.) OPTICAL ROTATOIZY POWER ON CHEMICAL CONSTIT'UTION.160 1 E X P E R I M E N T A L. 1 ; 4-Naphthylenebisiminocamphor. When camphorquinons (2 mols.) 1 4-naphthylenediamine dihydrochlorids (1 mol.) and excess of sodium acetate are thoroughly mixed a red colour is developed almost immediately. The mixture after being heated for half an hour on the water-bath a t 60-70° is extracted with alcohol and on diluting with water a red substance is deposited which crystallises from alcohol in red rectangular plates melting at' 228-229O (with blackening). It is solirblei in pyridine chloroform ethyl alcohol or methyl alcohol and insoluble in ether or water (Found N=6*33. C,,H,O,N requires N= 6.16 per cent.). The rotatory power deterniinations were made by dissolving the given weight of the substance in the given volume of the solvent, and the following results without any mutarotation were obtained.Ths length of 'the tub0 was O.5-dcm. in the case of pyridine and in the case of the remaining solvents it was 2-dcm. Sub-8 tance. Solvent. Gram. Chloroform ........................... 0.0213 ........................ 0.0186 Methyl alcohol ..................... 0.0181 Ethyl dcohol ........................ 0.0132 ........................ 0.0168 Pyridine ........................... 0.0 122 9 9 9 9 Volume. C.C. 40 100 100 100 100 50 Tem-perature. a,. [MI,. 18.1' 1,914' 8187' 18.8 0.668 8196 18.4 0,732 9052 18.4 0.706 12071 18.4 0.905 12239 30 0.36 13416 All attempts to reduce this compound have failed. For comparison with the foregoing substance the following measurements were made with p-phenylensbisiminocamphor : Sub-stance. Volume. Tem-Sol vent . Gram. C.C. perature. a,. [MI,. Chloroform ........................... 0.0286 20 24.5' 4-31' 6088 Methyl alcohol ..................... 0.0357 20 21.7 4-41 6009 ..................... 0-0254 20 21.7 3.15 5005 Ethyl dcohol. ....................... 0.0264 20 21-7 3.46 6289 9 9 THE CHEMICAL LABORATORY, GOVERNMENT COLLEGE, LAHORE PUNJAB INDIA. [Receiued November 9th 1020.1 VOL. cxm. 3