1OGS
VOL. 26
NOTES
I)eg:rn to separate in a few minutes. After the mixturc had stood at room temperature for about 20 hr. with occasional aeration, filtration afforded 0.30 g. (937, yield from 2mcthylthio-2-thiazoline) of fine white crystals, m.p. 144145.5'. Ilccrystallization from 1 : 1 aqueous ethanol gave glistening plates, m.p. 145-146.5'. The infrared spectra of this product and of the disulhde from the rearrangement were identical; there was no mixed melting point depression. The dihydroiodide of the disulfide, m.p. 244.5-246', wm isolated from an attcmptcd preparation of the mercaptan (111) from 2-methylthio-2-thiazoline hydroiodide' and 2mercaptoethylamine in refluxing methanol. The same compound waa obtained from IV and hydrogen iodide. Anal. Calcd. for CloHm12N4S4: C, 20.76; H, 3.49; S, 22.17. Found: C, 20.88; H, 3.57; S, 22.41.
Acknowledgment. The authors are indebted to
Mr. C. DiPietro and Mr. W. A. Sassaman for the microanalyses and to Mr. F. H. Bissett for the
that they are monomeric in benzene solution in the concentration range studied. A number of related organoboron compound8 containing the five-membered dioxaborolane ring (11) have been reported in the literature, and their physical properties have been described in some detail. Although they have generally been assumed to be monomeric in the liquid state, the only simpIe dioxaborolane for which an experimental molecular weight has been reported is 2-n-butoxy-1,3,2dioxaborolane (IIc), which was found to be monomeric in cyclohexane solution.6 The concentration used in this molecular weight determination was not specified. IIa. R = C1IIb. R t CiHs 0IIc. R a ~z-CIHI 0IId. R (CH& N-
infrared spectra. PIONEERING RESEARCH DIVISION A N D ENGINEERING CENTER QUARTERMASTER RESEARCH NATICK,MASS.
=i
o - R I1
The Molecular Weights of Some Simple Recently 2-chloro- (Ira): 2-n-butoxy-(IIc), and Borolanes and Borinanes 2-dimethylamino-l,3,2-dioxaborolanes(IId) have been prepared in this laboratory, and their physical R. J. BROTHERTON AMI A. L. MCCLOSKEY properties agreed with those reported by previous ~ v o r k e r s . ~It~was 6 ~ ~noted, however, that the chloroReceived June 27, 1960 borolane, IIa, is an extremely viscous compound with a boiling point which suggests a high degree Only a few s'imple derivatives of the six-membered of association in the liquid state. For example, dioxaborinane ring (I) have been reported in the chlorodimethoxyborane, (CHaO)ZBCl, which has a l i t e r a t u r ~ , ~and - ~ none of the materials described molecular weight of 108.3 compared to 106.3 for IIa, has a vapor pressure of 1 mm. a t -47'8 while IIa boiled a t 74" a t 1mm. Cryoscopic molecuIa. R=CIlar weights of the borolanes, IIa, IIc and IId, were I b. R = n-C4H,Odetermined in benzene solution, and the results I are shQwn in Table I. The chloro compound (IIa) apparently exists has been characterized by molecular weight de- in the dimeric form in benzene solutions in the con(Ia) was centration range studied. The only other examples terminations. 2-Chloro-l,3,2-dioxaborinaiie prepared from equivalent amounts of trimethylene of alkoxyhaloboranes which were reported to be glycol and boron trichloride. Conklin and Morris2 strongly associated in the liquid state are di~ ~ ~ ~n-butoxydifluoro~ originally described this reaction but did not char- f l u o r o m e t h o ~ y b o r a nle3 ~and acterize the chloro compound. Finch, ei aL.,3 who borane'* which were originally reported to be dihave prepared I a independently by a similar meric. Latcr M ~ C u s k e r ' ~suggested that these method, described it as a viscous liquid, whereas compounds were complexes having the general the product obtained in the present work was not formula, (RO)aB.2BFz. However, recent studies a viscous material at room temperature. Reaction of l a with n-butyl alcohol gave 2-n-butoxy-1,3,2(6) J. A. Blau, W. Gerrard, and M. F. Lqpcrt, J . Chem. dioxaborinane (Ib), a reaction which was also SOL,4116(1957). noted by Finch. The experimental molecular ( 7 ) R. L. Letsinger and I. H. Skoog, J. Am. Chem. SOC., weights of these borinsnes given in Table I show 76,4174 (1954). ( 1 ) The research reported in this document was supported in part by JVright Air Development Division of the U. S. Air Force under Contract A F 33(616)-5931. (2) G. W. Conklin and R. C. Morris, Brit. Patent 790,090 (1958). (3) P. J. Garner, Brit. Patent 722,538 (1955). (4) P. J. Garner, U. S. Patent 2,839,564 (1958). ( 5 ) A. Finch, J. C. Lockhart, and J. Pearn, Chem. 62 Ind., 471 (1960).
(8) E. Wiberg and W. Sutterlin, Z. anotg. Chem., 202, l(1931). (9) The extremely viscous nature of 2-chloro-1,3,2-dioxaborolane suggests that it is even more highly associated in the pure liquid state. (10) J. Goubeau and I
