72761-87-6

Upstream product

• 766-08-5 methylphenylsilane 
• 75-65-0 tert-butyl alcohol 
• 40907-20-8 1,1,1,2,3,4,4,4-octamethyl-2,2-diphenyl-tetrasilane 
• 75843-96-8 1-Phenylsilaethen 

Relevant academic research and scientific papers

Hydrosilane σ-Adduct Intermediates in an Adaptive Zinc-Catalyzed Cross-dehydrocoupling of Si?H and O?H Bonds

Three-coordinate PhBOX (Formula presented.) ZnR (PhBOX (Formula presented.) =phenyl-(4,4-dimethyl-oxazolinato; R=Me: 2 a, Et: 2 b) catalyzes the dehydrocoupling of primary or secondary silanes and alcohols to give silyl ethers and hydrogen, with high turnover numbers (TON; up to 107) under solvent-free conditions. Primary and secondary silanes react with small, medium, and large alcohols to give various degrees of substitution, from mono- to tri-alkoxylation, whereas tri-substituted silanes do not react with MeOH under these conditions. The effect of coordinative unsaturation on the behavior of the Zn catalyst is revealed through a dramatic variation of both rate law and experimental rate constants, which depend on the concentrations of both the alcohol and hydrosilane reactants. That is, the catalyst adapts its mechanism to access the most facile and efficient conversion. In particular, either alcohol or hydrosilane binds to the open coordination site on the PhBOX (Formula presented.) ZnOR catalyst to form a PhBOX (Formula presented.) ZnOR(HOR) complex under one set of conditions or an unprecedented σ-adduct PhBOX (Formula presented.) ZnOR(H?SiR′3) under other conditions. Saturation kinetics provide evidence for the latter species, in support of the hypothesis that σ-bond metathesis reactions involving four-centered electrocyclic 2σ–2σ transition states are preceded by σ-adducts.

Seeking Heteroatom-Rich Compounds: Synthetic and Mechanistic Studies into Iron Catalyzed Dehydrocoupling of Silanes

A detailed synthetic investigation into the dehydrocoupling of silanes with amines, phosphines, and alcohols using an iron precatalyst (1) is presented. We have furnished over 30 examples of aminosilane synthesis along with kinetic studies using MeBnNH and MePhSiH2 as coupling partners. The kinetic studies suggest a reversible reaction with silane which generates aminosilane and an Fe-hydride dimer that undergoes rate-limiting protonolysis with amine with N-H bond cleavage in the transition state, consistent with a primary KIE of 2.42(3). The presence of dimers as on-cycle intermediates was analyzed in depth. Beyond this we have explored the substrate scope of phosphinosilane formation which shows a preferential heterodehydrocoupling to give the phosphinosilane with primary and secondary silanes. Silylethers can also be prepared and alcohols that contain alkene functionality do not show any tendency to reduce the double bond.

Steady state and time-resolved spectroscopic studies of the photochemistry of 1-arylsilacyclobutanes and the chemistry of 1-arylsilenes

Direct photolysis of 1-phenylsilacyclobutane and 1-phenyl-, 1-(2-phenylethynyl)-, and 1-(4'-biphenylyl)-1-methylsilacyclobutane in hexane solution leads to the formation of ethylene and the corresponding 1-arylsilenes, which have been trapped by photolysis in the presence of methanol. Quantum yields for photolysis of the three methyl-substituted compounds have been determined to be 0.04, 0.26, and 0.29, respectively, using the photolysis of 1,1-diphenylsilacyclobutane (Φ(silene) = 0.21) as the actinometer. The corresponding silenes have been detected by laser flash photolysis; they have lifetimes of several microseconds, exhibit UV absorption maxima ranging from 315 to 330 nm, and react with methanol with rate constants on the order of (2-5) x 109 M-1 s-1 in hexane. Absolute rate constants for reaction of 1-phenylsilene and 1-methyl-1-phenylsilene with water, methanol, tert-butanol, and acetic acid in acetonitrile solution have been determined, and are compared to those of 1,1-diphenylsilene under the same conditions. With the phenylethynyl- and biphenyl-substituted methylsilacyclobutanes, the triplet states can also be detected by laser flash photolysis, and are shown to not be involved in silene formation on the basis of triplet sensitization and (or) quenching experiments. Fluorescence emission spectra and singlet lifetimes have been determined for the three 1-aryl-1-methylsilacyclobutanes, 1,1-diphenylsilacyclobutane, and a series of acyclic arylmethylsilane model compounds. These data, along with the reaction quantum yields, allow estimates to be made of the rate constants for the excited singlet state reaction responsible for silene formation. 1-Methyl-1-phenylsilacyclobutane undergoes reaction from its lowest excited singlet state with a rate constant 10-80 times lower than those of the other three derivatives. The results are consistent with a stepwise mechanism for silene formation, involving a 1,4-biradicaloid intermediate that partitions between product and starting material.

Conversion of hydrosilanes to alkoxysilanes catalyzed by Cp2TiCl2/nBuLi

The combination of Cp2TiCl2 and nBuLi provides an effective catalyst for alcoholysis of the model silanes n-HexSiH3, PhMeSiH2, Ph2SiH2 and PhMe2SiH by ethanol, isopropanol, t-butyl alcohol and phenol.Increasing the steric bulk of the substituents on either the alcohol or the silane generally requires longer reaction periods and/or increasing temperature.All SiH bonds are converted to SiOEt groups by ethanol and a single SiH bond in secondary silanes and two SiH bonds in tertiary silanes are replaced by t-butyl alcohol.Diols including pinacol, 2,4-pentanediol and 2,5-hexanediol react with PhRSiH2 (R = Me, Ph) to give 1,3-dioxa-2-silacyclopentanes, -hexanes and -heptanes, respectively.Attempts to form caged structures by condensation of primary silanes and triols was unsuccessful.Hydrolysis of PhRSiH2 is promoted by Cp2TiCl2/n-BuLi and the siloxane is produced in quantitative yield when R = Ph and a mixture of linear disiloxanes and trisiloxanes in addition to cyclopolysilanes are produced when R = Me.Other protic reagents including acids, mercaptans, amines and enolizable ketones did not react.The effects of reaction parameters such as temperature, silane to catalyst ratio, solvent, transition metal and replacements for nBuLi were also determined.

INSERTION OF DIMETHYLSILYLENE INTO O-H AND N-H SINGLE BONDS

Dimethylsilylene, generated by photolysis of dodecamethylcyclohexasilane, inserts efficiently into O-H single bonds of alcohols to yield alkoxydimethyl-silanes.Use of ethanol-O-d1 yields ethoxydimethylsilane-Si-d1.Dimethylsilylene also inserts into O-H single bonds of water or D2O to yield respectively tetramethyldisiloxane or tetramethyldisiloxane-Si2-d2.Dimethylsilylene also inserts into N-H bonds of primary and secondary amines to yield aminodimethylsilanes.This reaction provides an efficient route to difunctional silanes.