OPTICALLY ACTIVE PINENE NITROSOCHLORIDE, ETC.
36p
beating requires great care and considerable experience in order to avoid an undue amount of breakage. They must be heated over, not on the :;ide of a burner, the marked side toward the flame. It is our opinion that a muHe should be used where a large amount of slides are to be marked, using a strip of zinc (map. 4x2’ c.)and a Seger cone 0 2 2 , to indicate the temperature limits- Since a muffle furnace was not available, we were unable to carry out this experiment. The marked slides, after being thoroughly dried, may be sent to some shop where glass firing one and finished there for a nominal charges1 JOSBPH C. BOCK. [CONTRIEIUTION FROM
EXPGRIMENT STATION ]
T H WISCONSIN ~ PHARMACEUTICAL
TICALLY ACTIVE PINENE NITROSOCHLORIDE AND SYNTHETICAL ACTIVE PZRENE. BY E. V. LYNN. Received November 4, 1918.
The nitroso compounds, characterized by the group --N = 0, were first prepared by Cahours,2 in 1842. The discovery by Tilden,$ in 1875~ that they could be prepared by addition to unsaturated compounds, and Ihe subsequent improvement in the method by Walls( h,4 in 1888, first placed these nitroso cornpounds in the important position they have since occupied. Although a blue coloration generally accompanies the commencement of the reaction, the compounds which result are, in most instances, colorless. The latter have been shown to be isonitroso compounds,6 characterized by the group = N-OH, or hisnitroso compounds,6R’-NzOz-R’. Since the blue substances which have been isolated’ are shown to be true nitroso in character, and since they readily change t o the isomers8 A semi-permanent marking medium can be obtained by mixing a pigment (lead oxid, lampblack, etc.) with a good spar varnish, Canada balsam or collodion varnish (banana liquid). It will resist the ordinary cleaning and has been found useful for marking stock bottles and similar containers. A m Z .41, , 76-77 (1842). J . Chem. SOL., [ 2 ] 13, 514-518 (1875); Ibid., 31, 554-561 (1877); Pharm. J., [IIIj 8, 188-191 (1878). Ann., 241,241-254 (1888); 253, 249-267 (1889). 6 Goldschmidt, Bey., 18, 1729 and 2 2 2 0 (1885); Krerners and Urban, Am. Chem, J., r 4 , 395-404 (1894); Meyer, Bey., 21, 1291-1295 (1888); Krerners and Mead, Am. Chem. J,, 17,607-611 (1895). Kremers, InazLg. Diss., Gottingen, 1890;Baeyer, Ber., 28, 639-652 (~8953. 7 Wallach, Ann., 241,312 (1887); Baeyer, Ber., 27, 436-454 (1894); Thiele, Ibid., 27, 454-456 (1894); Chapman, J. Chem. SOL.,67, 780-784 (1895);Piloty, Ber., 31, 218-220 (1898); Kremers and Schreiner, Pharm. Arch., 2, 273300 (1899); Schmidt, Bey., 35, 3373 and 3727 (11902); Piloty and Steinbock, Ibid., 35, 31013117 (1902); Schmidt, Paid., 36, 1765-1768 (Sg03). 8 Kremers and Schreiner, Pharm. Arch., 2 , 273-300 (1899).
mentioned above, it is assumed that the initial blue color indicates the formation of true ni troso compounds. 'Whenever these true compounds may be expeiied because of the reagents employed, they seldom crystallize out, but in most instances, isonitroso or bisnitroso compounds are obtained. That side reactions likewise take place is not at all surprising; indeed this is to be expected by one who has worked a t all extensively with these compounds and the reaction mixtures from which they are obtained. Sometimes the crystalline products are formed with almost theoretical yield (nitrosothymol 100%~limonene nitrosochloride 8 0 % ) ~ but mostly they are obtained in smaller amounts (pinene nitrosochloride o to 50%). The capacity for reaction which these crystalline compounds manifest is so great that chemists quite generally have been content to follow the lines of least resistance, and have given their time and attention to them, paying but little heed to the mixtures from which they arise. It is true that Wallachl has isolated pinol and cymene from pinene nitrosochloride mother liquor, and that Kremers and Hanf2 have found a compound, analogous to pinol, in that from limonene nitrosochloride, but in both eases it was the decomposed liquid which was examhed. In 1891 Kremers3 observed a wide difference in yield of nitrosochloride from pinene of different sources and, in 1892, showed4 that .the yield varies inversely with the optical rotation of the pinene, a result which has been confirmed in the present work and by many other investigato~s.~ In order to account for this variation we must consider the facts that: ( I ) the nitrosochloride obtained is always inactive; ( 2 ) an increase in optical rotation of the pinene diminishes the yield; (3) the mother liquor remains blue for some time; (4) there is frequently a wide difference in solubility between .the inactive and active modifications of nitroso derivatives. fi With these facts in mind, it was but natural for us to suppose that it is the nitrosochloride from the inactive pinene which crystallizes out. A pinene which is naturally inactive gives the largest yield, and this inactivity andl consequent increase in amount oE product can also be: brought about by mixtures of levo and dextro pinene^.^ All attempts, however, to obtain derivatives of the active nitrosoWdliach, Anla., 253, 249-267 (1889);336, 8 (1904). Kremers and Hanf, Proc. Wisconsin Pharm. Assoc., 1893, pp, 47-49. Ibid., 1891,pp. 39-41 and 41-43. Ibbid., 1892, pp. 66-yo and 72-73. 6 Fox, Thesis, Univ. of Wisconsin, 1903;Tilden, J . Chem, SOL,85, 759-764 (1904); Gildemeister and Kohler, Wallach Festschr., 1909,p. 432 ; Schimmel & Co., Report, April, 19x0,p. 164; Lynn, Thesis, Univ. of Wisconsin, 1910;Brandel (1903), Unpublished results; Bandt ( I ~ I O )Unpublished , results. 6 Kremers, Znaug. Diss., Gottingen, 1890. 7 Kremers and Smith, Proc. Wisconsin Pharm. Assoc., 1892,p. 72-73.
OPTICALLY ACTIVE PINENE XITROSOCHLORIDE,
ETC.
363
chloride from the mother liquor gave negative results. Even the mixing sl fresh mother liquors from dextro and from levo pinene gave no precipitate of inactive nitro: ,chloride. I Later, Tilden? investigated the cause of this variation of yield with optical activity of the pinene and came to a very different conclusion. Since Baeyer3 had suggested that the crystalline nitrosochloride is a bisnitroso compound, Tilden decided that the poor yield with pinene of high rotation is due to the destructive eflects of the heat generated in the inversion of one-half of the product as soon as formed. On this basis, howe ~ e ra, difference in external conditions should alter the amount of nitrosochloride obtained, which is contrary to experience. for Preparing Pinene It was assumed, therefore, that the persistent blue color of the mother liquor is due to optically active pinene nitrosochloride in solution. Since the presence of acetic acid and of water in Wallach's method4 might easily alter this active compound, making it impossible of isolation, the method was modified by elimination of the acetic acid and by substitution of alcoholic hydrogen chloride for the aqueous hydrochloric acid. The method T L Q W used to prepare pinene nitrosochloride is as follows : Equal volumes of pinene, ethyl nitrite, and absolute alcohol are mixed mrb cooled in a freezing mixture. A solution of hydrogen chloride in absolute alcohol is added, in amount corresponding to the theoretical requirements for the pinene used. A thermometer is held in the reaction nd the temperature maintained below -5 by constant agitaregulation of the addition. The hydrogen chloride solution may be added quite rapidly, but the temperature regulation is essential rmtil the filtration is completed. After standing about one-half hour the crystals are filtered off. I n the preparation of larger quantities, the absolute alcohol used as a solvent may be replaced by 95% alcohol. The yield is slightly better than by the old method, but the principal advantage is that the reaction is easier to control. If the alcohol is omitted, the mother liquors can be kept for days without noticeable change in color, a t least in the dark and if slightly deficient in acid. In fact, one fJtrate was preserved with a blue-green color a t oo for over three weeks. Optically Active inene Nitrosochloride. The filtrates from the above method, after the further addition of one to two volumes of alcohol, were exposed to temperatures below -IO'. After a longer or shorter time, depending upon the temperature and upon the optical rotation of the pinene used, crystals separated in the form of 2
Giidemeister and Kohler, Wallach Pestschr , 1909,p 432. J Chew S o c , 85,759-764 (1904) Be? , 28, 639-652 (1895) A n n , 245, 241-254 (188G), 253, 249-267 (1889)
E. v. LYNN.
3%
colorless, transparent needles or cotton-like needles, the latter from samples containing more alcohol. The product was purified by washing with cold alcohol. The best yield, as night be expected, was from pinene of high rotation. Thus, a pinene from Chamaecyparis lawsoniana (Murr.) Parlatone, with a specific rotation of $47 7 O , gave no trace of inactivell but about 15% yield of the active nitrosochloride. In this case the crystals separated in a few minutes. ~
I. Subs., 0.5862 g.; AgCI, o .4180 g. 11. Subs., o .4213 g.; Age?, o .3009 g. :%I. Subs., o ,5787g.; at 21 and 732 mm., 36 .g cc. moist N. IV. Subs., o ,6001 g.; a t 20' and 732 mm., 40.I cc. moist N. W. Subs., 0.2670 g.; HaO, 5.1975 g.; COa, 0.5863 g. O
Pound.
