Direct conversion of amines to the corresponding halides by deamination with t-butyl thionitrite or t-butyl thionitrate and copper(II) halides
✍ Scribed by Yong H. Kim; Kōichi Shinhama; Shigeru Oae
- Book ID
- 104246292
- Publisher
- Elsevier Science
- Year
- 1978
- Tongue
- French
- Weight
- 197 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0040-4039
No coin nor oath required. For personal study only.
✦ Synopsis
We reported recently that both t-butyl thionitrite')and t-butyl thionitrate')can be prepared simply by treating t-butyl mercaptan with dinitrogen tetraoxide.
We now have found that various arylamines reacted readily with either t-butyl thionitrite or t-butyl thionitrate and copper(I1) halides under mild conditions to afford the corresponding halides in good yields(eq 1).
t-Bu
-S-N=0 1 + ArNH2 + CuX2 CH3CN or t-Bu-SNO, o-25°c p ArX + N2 + (t-Bu-)2S2 + (t-Bu-)2S3 -----(1) L X=Cl, Br Both thionitrites and thionitrates are generally known to be unstable, however, t-butyl derivatives.i.e., t-BuSNO and t-BuSN02, which can be readily synthesized quantitatively by mixing the thiol and N204, are stable enough to be used for these reactions. Although other nitrosyl compounds such as nitrosyl halide 3) and alkyl nitrite 4) have been successfully used for the same reaction, thionitrites or thionitrates are considered to be better reagents for deaminative halogenation of arylamines due both to the relatively weaker S-N bond of t-butyl thionitrite or t-butyl thionitrate than the O-N bond of nitrites and also to the stronger complexation of thio-derivatives with copper salt than the oxygen and chloro analogs. Indeed, this was found to be the case. After a solution of t-BuSNO(0.899, 7.5 mnol, CH3CN:20 ml) was added onto well-dried CuC12(0.85g, 6 mnol) under argon with vigorous stirring, a solid or liquid aromatic amine was slowly added over a period of 15 min. at 25°C and then hydrochloric acid solution (20%, 100 ml) was added. The solution, after saturated with NaCl, was extracted with ether. The extract was washed 3 times with water saturated with NaCl and then concentrated. Purification by TLC or recrystallization gave the pure mono-halogenated product. Other products were t-butyl disulfide(ca. 0.35 mnol) and t-butyl trisulfide(ca. 2.0 mn01)~) t-Butyl trisulfide was identified by elemental analysis.
Quantitative evolution of N2 collected during the reaction was identified by mass-spectroscopy.