| OBSERVATION'S |
The procedure described by Kumada Makoto [J. Org. Chem., 21, p. 1264 (1956)] for prepn of substituted disilanes through protonation of (Me)6Si2 with SO4H2 is still widely referenced Co.'s authors recently experienced an explosion during distn of crude DCTMDS (I). Investigation revealed that crude (I) contained silylsulfates or dissolved SO4H2. Increased reaction time with SO4H2 may have contributed to oversulfation. An ARC test on crude (I) under N2 atm showed an exotherm with onset at 145C that totaled over 600 J/g. A pressure rise with evolution of SO2 occurred with exotherm. A mixt of 10% concn H2SO4 & (I) showed similar exotherm. Pure (I) was found to be stable. The thermal decompn of crude (I) is autocatalytic, requiring 50 min at 150C, 10 min at 175C or sec at 190C to reach explosive conditions. This occurs in absence of air or water Winton Patnode & F.C. Schmidt reported the instability of silylsulfates during distn of bis( trimethylsilyl)sulfate [J. Am. Chem. Soc., 67, p. 2272 (1945)], which is currently available for use as a trimethylsilylating agent. Authors performed DSC analysis on this commercial material & observed an exotherm with onset at 225C & releasing 202 J/g Authors would like to reiterate the use of caution when following the Kumada procedure or similar procedures using SO4H2 to protonate organosilanes, as well as when using silylsulfate reagents |
| UPDATE | 06.01 |
| AUTHOR | This data is not available for free |
| COMPANY | This data is not available for free |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |