Loading...
Please wait, while we are loading the content...
Similar Documents
Silylations of some polyhalogenated compounds
| Content Provider | Semantic Scholar |
|---|---|
| Author | Ballard, David H. Brennan, Thomas Fearson, F. W. G. Shiina, Kyo Haiduc, Ionel Gilman, Henry |
| Copyright Year | 1969 |
| Abstract | INTRODUCTION The search for thermally stable polymers has led to an expanding study of organosilicon compounds. Among the most promising types seem to be those including polyhalogenated aromatic nuclei linked to the organosilicon moieties. In an effort to obtain monomeric model compounds of various structures, whose chemical and physical properties could suggest new routes to polymers of the types mentioned above and would permit a priori evaluation of the properties of such polymers, an extensive investigation of the silylation of polyhalogenated organic compounds was initiated in this laboratory. The results were rewarding, especially in the sense that several unusual and unexpected reactions were found. Two main approaches for the silylation of polyhalogenated compounds were considered: (a) the direct reaction of polyhalogenated compounds with lithium or magnesium and chiorotrimethylsilane or other chiorosilanes; and (b) metalation or halogen-metal exchange between the halogenated aromatic compounds and organolithium reagents, followed by derivatization with chiorotrimethylsilane and other chlorosilanes. It was found that the first approach, (a), gave polysilylated compounds (via Wurtz-Fittig type couplings) only when a haloaromatic compound was treated with stoichiometric amount or a slight excess of lithium (or magnesium) and chiorotrimethylsilane. When attempts were made to force the silylation, in order to obtain highly silylated derivatives by reacting polyhaloaromatic compounds with a large excess (ten to twenty fold) of lithium and chlorotrimethylsilane, an unusual formation of tetrakis(trimethylsilyl)allene was observed with the cleavage of the aromatic ring. This happened when the aromatic parent compound contained at least four halogen atoms and/or some trimethylsilyl substituents on the ring. With p-dihalobenzenes reductive silylation occurred under similar conditions, with the formation of cyclohexadiene derivatives. Aliphatic polyhalogenated compounds, with an excess of lithium (or magnesium) and chlorotrimethylsilane, also gave tetrakis(trimethylsilyl)allene, but monoand di-acetylenes were obtained in certain cases. The second approach, (b), afforded the synthesis of polysilylated halobenzcnes without difficulty. In connection with these studies selective action of certain organolithium reagents was observed, as well as simultaneous halogen-metal and hydrogen-metal interconversions in a polyhalogenated benzene. |
| Starting Page | 449 |
| Ending Page | 472 |
| Page Count | 24 |
| File Format | PDF HTM / HTML |
| DOI | 10.1351/pac196919030449 |
| Alternate Webpage(s) | http://media.iupac.org/publications/pac/1969/pdf/1903x0449.pdf |
| Alternate Webpage(s) | https://doi.org/10.1351/pac196919030449 |
| Volume Number | 19 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
