- Synthesis of 2,2,5,5-Tetrasubstituted 1,4-Dioxa-2,5-disilacyclohexanes via Organotin(IV)-Catalyzed Transesterification of (Acetoxymethyl)alkoxysilanes
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(Acetoxymethyl)silanes 2, 7 a-c, and 10 a-c with at least one alkoxy group, of the general formula (AcOCH2)Si(OR)3-n(CH 3)n (R: Me, Et, iPr; n=0, 1, 2), were synthesized from the corresponding (chloromethyl)silanes 1, 6 a-c, and 9 a-c by treatment with potassium acetate under phase-transfer-catalysis conditions. These compounds were found to provide 2,2,5,5-organo-substituted 1,4-dioxa-2,5- disilacyclohexanes 3, 8 a-c, and 11 a-c if treated with organotin(IV) catalysts such as dioctyltin oxide. The reaction proceeds through transesterification of the acetoxy and alkoxy units followed by ring-closure to form a dimeric six-membered ring. The corresponding alkyl acetates are formed as the reaction by-products. With these mild conditions, the method overcomes the drawbacks of previously reported synthetic routes to furnish 2,2,5,5-tetramethyl-1,4-dioxa-2, 5-disilacyclohexane (3) and even allows the synthesis of 1,4-dioxa-2,5- disilacyclohexanes bearing hydrolytically labile alkoxy substituents at the silicon atom in good yields and high purity. These new materials were fully characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and X-ray analysis (trans-8 a). Tin makes the ring! Easily accessible (acetoxymethyl)silanes with at least one alkoxy group give 2,2,5,5-organo- substituted 1,4-dioxa-2,5-disilacyclohexanes (see figure) in good yields and high purity when treated with organotin(IV) catalysts. The mild reaction conditions even allowed the synthesis of cyclic silanes with hydrolytically labile alkoxy substituents. Copyright
- Erhardt, Sascha A.,Hoffmann, Florian,Daiss, Juergen O.,Stohrer, Juergen,Herdtweck, Eberhardt,Rieger, Bernhard
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p. 4818 - 4825
(2013/05/09)
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- METHOD FOR PRODUCING ESTER-FUNCTIONAL SILANES
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Silanes containing an ester group are produced in high yield and purity by reacting a salt of a carboxylic acid with a silane containing a carboxylate substitutable leaving group following by distilling the product mixture to obtain a distillate containing the ester group containing silane product, wherein a solvent having a boiling point higher than the product is contained in the product mixture during at least a terminal portion of the distillation.
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Paragraph 0094; 0095
(2013/03/26)
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- Hydroxymethyltrialkoxysilanes and methods of making and using the same
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Novel hydroxymethyltrialkoxysilanes of the formula: STR1 are produced by transesterifying a carboxylic acid ester of hydroxymethyltrialkoxysilane with an alcohol, and distilling the reaction mixture to remove the carboxylate of the alcohol. The carboxylic acid ester of hydroxymethyltrialkoxysilane is prepared by the reaction of an alkali metal carboxylate with chloromethyltrialkoxysilane, which in turn is prepared by the reaction of a trialkylorthoester with chloromethyltrichlorosilane by heating to reflux with removal of alkylchloride, followed by distillation to remove alkyl ester. The hydroxymethyltrialkoxysilanes and carboxylic acid esters thereof, as well as carboxymethyltrialkoxysilanes, are particularly useful in sol-gel processing by undergoing hydrolysis to yield hydroxymethylsilanetriol, and subsequent hydrolysis and polycondensation products.
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