66239-88-1Relevant academic research and scientific papers
Storing of the Labile Silaethene Me2Si=C(SiMe3)2 with Benzophenone
Wiberg, Nils,Preiner, Gerhard,Schurz, Klaus,Fischer, Gerd
, p. 1468 - 1474 (2007/10/02)
Benzophenone Ph2C=O is able to "store" the silaethene Me2Si=C(SiMe3)2 (1), produced from Me2SiX-CLi(SiMe3)2 (X = F, Br, Ph2PO4), under formation of a cycloadduct (2b).At about 100 deg C, 2b by way of 1 transfers into the cycloadduct of 1 and Ph2C=O (3b), which in the course of transformation decomposes visibly (in the absence of Me3SiCl) or only by traces (in the presence of Me3SiCl) to secondary products.In the presence of ROH (R = H, Me, tBu, MeCO) or PhN=NSiMe3 or RN3 (R = tBu, Me3Si) or 2,3-dimethylbutadiene (dmb) about 100 deg C 2b and 3b form by way of 1 insertion products of 1 into the OH bond of ROH or a cycloadduct of 1 and PhN=NSiMe3 or cycloadducts of 1 and RN3 or cycloadduct and an ene reaction product of 1 and dmb.The rate constants/half lives of the first order transformation of 2b into 3b or of the first order decomposition of 2b or of 3b in the presence of reactive traps for 1 (ROH, Me3SiN3; benzene as solvent) are in the order of 0.3E-4 s-1/τ1/2 = 7 h (2b --> 3b; 90 deg C) 3E-4 s-1/τ1/2 = 3/4 h (2b + traps; 90 deg C), 0.4E-4 s-1/τ1/2 = 5 h (3b + traps, 110 deg C). - Keywords: Silaethene Me2Si=C(SiMe3)2, Insertions, Cycloadditions, Kinetic Studies
Storage of Silan- and Germanimines Me2E=NR (E = Si, Ge) by Way of Sila- or Germadihydrotetrazoles
Wiberg, Nils,Karampatses, Petros,Kim, Chung-Kyun
, p. 1213 - 1222 (2007/10/02)
Silan- and germanimines Me2E=NR (1, 2) ntBu3-n, SiPh3, EMe2N(SiMe3)2> react with azidoalkanes or -silanes R'N3 ntBu3-n, SiPh3, SiMe2N(SiMe3)2> by cycloaddition to form sila- or germatetrazoles 5, 6 (in addition, insertion products of Me2E=NR in the R'N bond of the azides and others are formed in some cases).The sila- or germadihydrotetrazoles decompose at raised temperatures in a first-order reaction, reversing their formation by cycloreversion into azides R'N3 or RN3 and imines Me2E=NR or Me2E=NR' (rate constants: Table 1).Consequently, azides operate as stores for silan- and germanimines.The unsaturated systems are formed only as short-lived intermediates.Their stabilization, as a rule, takes place by dimerization and/or insertion of the imines into the RN or R'N bond of the azides, formed as well by thermolysis of dihydrotetrazoles.
Reactivity of the Labile Silaethene Me2Si=C(SiMe3)2, Stored as Ph2C=NSiMe3 Adducts
Wiberg, N.,Preiner, G.,Wagner, G.,Koepf, H.
, p. 1062 - 1074 (2007/10/02)
Silaethene Me2Si=C(SiMe3)2 (1), stored as Ph2C=NSiMe3 adducts and regenerated from the adducts at about 100 deg C as a reaction intermediate, combines with reactants a-b (e.g.HO-H, RO-H, RCOO-H, RS-H, RHN-H, Ph2CN-H, RO-SiR3, R2N-SiR3, Ph2CN-SiR3, Cl-GeR3, Cl-SnR3) with insertion into the a-b bond, with a=b (e.g.O=CPh2, Me3SiN=CPh2, CH2=CHOMe, cis-piperylene), a=b=c (e.g.RN=N=N, O=N=N), a=b-c=d (e.g. butadiene, isoprene, trans-piperylene, 2,3-dimethylbutadiene, cyclopentadiene, anthracene, benzophenone, N-trimethylsilylbenzophenoneimine) under -, - as well as -c ycloaddition and with a=b-c-H (e.g. propene, butenes, isoprene, 2,3-dimethylbutadiene, acetone) under ene reaction.According to relative reaction rates, insertion and -cycloadditions seem to proceed in two reaction steps, whereas -cycloadditions and ene reactions with organic dienes and enes obviously are one step reactions.For reactivities cf.Table I. - Key words: Silaethene Me2Si=C(SiMe3)2, Insertions, Cycloadditions, Relative Reactivities
