Silicon amines, tertiary

Synthesis of Silicone Monomers and Intermediates. Another important reaction for the formation of Si—C bonds, in addition to the direct process and the Grignard reaction, is hydrosdylation (eq. 3), which is used for the formation of monomers for producing a wide range of organomodified sihcones and for cross-linking sihcone polymers (8,52—58). Formation of ether and ester bonds at sihcon is important for the manufacture of curable sihcone materials. Alcoholysis of the Si—Cl bond (eq. 4) is a method for forming silyl ethers. HCl removal is typically accomphshed by the addition of tertiary amines or by using NaOR in place of R OH to form NaCl. 

Formulations for one-shot polyether systems are similar to those used for flexible foams and contain polyether, isocyanate, catalyst, surfactant and water. Trichloroethyl phosphate is also often used as a flame retardant. As with polyesters, diphenylmethane di-isocyanate is usually preferred to TDI because of its lower volatility. Tertiary amines and organo-tin catalysts are used as with the flexible foams but not necessarily in combination. Silicone oil surfactants are again found to be good foam stabilisers. Volatile liquids such as trichlorofluoro-methane have been widely used as supplementary blowing agents and give products of low density and of very low thermal conductivity. 

Summary New lyophilic cationic silicone surfactants have been synthesized by direct quatemization of halogenated siloxanyl precursors or by transformation of these precursors into tertiary amines with a subsequent quatemization step. After transformation of the precursors into secondary amines, reaction with maleic anhydride and neutralization, new anionic products were obtained. 

Irradiation at 77 K in trichlorofluoromethane of cyclic tertiary amines also affords radical cations that can be trapped indefinitely. In these systems there apparently is no reaction between the radical cations and free amine. The EPR spectra of the radical cations were recorded. The cations produced under these conditions can be trapped indefinitely and do not undergo proton loss to give the corresponding carbon-centred radical. Several systems (20-24) were examined in this way and all were found to be stable. In the bis amine (22, n = 1) evidence was obtained from the EPR study that there was weak N-N interaction4. The influence of silicon in 25 was also examined16. 

The decomposition of arenediazonium tetrafluoroborates in the resulting fluoroarene as solvent has also been utilized.179 This method is very fruitful in the synthesis of fluorobenzene (96% yield) or fluorotoluenes (85-88% yield for the three isomers) but fails with substrates such as anisolediazonium tetrafluoroborates which probably arylate the reactive fluoroaromatic solvent. In contrast, perfluorinated tertiary amines (EF-L 174, F-C 40), perfluorinated alkyl tetrahydropyran (EF-L 102), perfluorodecahydronaphthalene (Flutec PP7) or other per-fluorocycloalkanes (Flutec s) are claimed to be the best media for fluorodediazoniation of all types of diazonium tetrafluoroborates.224 These media seem to be more efficient, at least in the synthesis of 1,2-difluorobenzene, than silicone oil which has also been claimed to improve fluorodediazoniation.225... 

While tertiary amines often form quite stable adducts with N— Si bonds (see Section III,D), ammonia and primary or secondary amines normally cleave silicon-metal bonds intermediate adducts are either not observed or found only at low temperatures 134, 235). Typical behavior is shown by 28, 30, 31)... 

In addition to pyrolysis, transamination, and dehydrohalogenation with tertiary amines several other reactions have been described which yield access to the 1,3,2-diazaboracycloalkane system. For example, Abel and Bush 19> reported the ready replacement of silicon by boron in certain heterocyclic systems as illustrated in Eq. (6). It seems quite likely that this procedure can be developed into a general synthesis. On the other hand, the interaction of trialkylboranes with bis(l,3-diphenylimidazolid-... 

Vinylchlorosilanes also have been prepared by the direct reaction of vinyl chloride with silicon, but the comparative unreactivity of the chlorine attached to a vinyl group keeps the yields low. However, vinyltrichlorosilane and divinyldichlorosilane both have been isolated from the reaction mixture,63 and their constants appear in the table. Both compounds also may be made by chlorinating the corresponding ethylchlorosilanes (which may be made by the direct reaction) and then extracting hydrogen chloride with a tertiary amine such as quinoline ... 

The simultaneous protection of the 3 and S hydroxy groups of nucleosides and the 4,6- or 3,4-hydroxyls of hexopyranoses is a common problem in organic synthesis. In the case of hexopyranoses, we have already seen that benzylidene acetals and, in certain circumstances, isopropyiidene acetals can be used to good effect. An alternative silicon-based group would offer a wider repertoire of conditions for mild deprotection and such a group was devised by Markiewicz the 1,1,3,3-tetraisopropyldisiloxanylidene group (abbreviated TIPDS),22 229 TIPDS groups are stable to water, 0.3 M p-toluenesulfonic acid in dioxane, 10% tri-fluo mace tic acid in chloroform, 5 M ammonium hydroxide in dioxane-H20 (4 1), and tertiary amines in pyridine,... 

In the early 19th century, Gay-Lussac discovered F Si 2 NHj. Three years later Davy obtained the same compound and Davy and Berzelius synthesized other compounds of six-coordinate silicon fluorosilicic acid, HjPiFg], and its salts, the hexafluorosilicates In the second half of the last century adducts of silicon tetrahalides with tertiary amines were synthesized . In 1903 Dilthey investigated silicon diketonates containing six-coordinate silicon In the first half of our century the possibility of the presence of Si(OH)g ions in silica was widely discussed Interest in five- and six-coordinate silicon compounds increased in the second half of the present century. As a result, new classes of silicon compounds with an expanded coordination sphere were discovered and were studied by various physical and chemical methods. Specific biological activity was observed for some of the compounds and promising ways of their practical application were planned... 

Ammonio- and phosphoniohexafluorocyclobutanide ylides 11, prepared from pcrfluorocy-clobutene and tertiary amines or phosphanes, are soluble in a wide range of (even nonpolar) organic solvents and transfer fluoride, and therefore can be used as an easily soluble source of fluoride anions. Although they contain no ionic fluoride they react with fluoride anion acceptors such as silicon derivatives with elimination of thermodynamically favored fluoro-trimethylsilane to produce carbanions which can be quenched with suitable electrophiles. The reaction proceeds upon slightly heating the reactants in tetrahydrofuran or dimethylform-amide solution. 

Silicon tetrafluoride reacts with epoxides in the presence of a tertiary amine to give fluorohydrins by a mechanism that probably involves five- or six-coordinate silicon species (equation 21). The ionization of Sip4 by electron impact affords SiFj + (where x = 1, 2, or 3), which can form clusters with neutral Sip4 and react with a range of small inorganic molecules. ... 

In addition to the formation of silyl enol ethers, isomerization of epoxides to allylic alcohols is another highly typical transformation performed by combination of a silicon Lewis acid with a tertiary amine. Reaction with la was examined, and its scope and limitation reported, by Noyori [61]. Epoxide 44 can be successfully converted into the corresponding allyl silyl ether 45 (Sch. 34). 

The chemistry of trichlorosilane—tertiary amine combinations Reactions of elementary silicon... 

Auxiliary blowing agent - Fluorocarbon Catalyst - Organotin salt Catalyst - Tertiary amines Surfactant - Silicone copolymer... 

Although there are no informations available concerning the structure of the dilithiated 1,3-diamines in solid phase or in solution, subsequent reactions of la,b with di- and trichlorosilanes support the existence of these dianions. la,b are important building blocks in organoelement synthesis, not only restricted to the field of silicon chemistry. Remarkable results have been achieved in reactions with N- or C-substituted dichlorophosphanes. An extension to germanium and tin is possible, but side reactions or lower yields are often observed. Nevertheless, the facile double metalation of TMMDA and CMMDA is unique for tertiary amines (e g., the phosphorus homologue (CH3)2PCH2P(CH3)2 is only metalated at the methylene carbon atom [8]). 

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