- The Synthesis of Ketones via α-Silyl Sulphides
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α-Phenylthiosilanes (2) have been prepared by alkylation of the anion (4) derived from the 1-phenylthio-1-trimethylsilylalkane (1).These anions (4) have benn prepared by a variety of methods including, direct deprotonation of (1), displacement of a phenylthio group by lithium naphthalenide addition of an alkyl-lithium to 1-phenylthio-1-trimethylsilylethene (7), and transmetallation of a tributylstannyl moiety.The formation of an alkyl-lithium by reaction of lithium naphthalenide with a phenyl sulphide provided an additional route to (2) from bis(phenylthio)acetals (8).An alternative path to the α-phenylthiosilanes (2) was to reduce the corresponding α-phenylsulphonylsilane (15); these, in turn, being readily available from alkylation or silylation of α-sulphonyl anions.The α-phenylthiosilanes (2) were converted into the O-trimethylsilylphenylthioacetal (18) by the sila-Pummerer rearrangement, although this was complicated by vinyl sulphide (20) formation in certain cases.Subsequent hydrolysis of (18) and (20) gave the ketone (3).
- Ager, David J.
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p. 195 - 204
(2007/10/02)
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- Kinetics and Mechanism of Oxidation of Alcohols by Ceric Ammonium Nitrate
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The main product of the oxidation of secondary alcohol by ceric ammonium nitrate is the corresponding ketone.The reaction is of first-order with respect to the oxidant but exhibit a Michaelis-Menten type kinetics with respect to the alcohol.The formation constants of the alcohol-CeIV complex and its thermodynamic parameters have been calculated.The rate of decomposition of the complex and the activation parameters have also been evaluated.The rates of decomposition of the complex correlate with Taft's ?* values with a low negative reaction constant.The oxidation induced polymerisation of acrylonitrile.The retardation of rate with increasing acidity has been explained on the formation of kinetically inactive protonated alcohol.The protonated constants for the various alcohol have been calculated.The presence of a small primary kinetic isotope effect, kH/kD = 2.3, confirms that the rate-determining step involves a C-H bond rupture in a non-symmetrical transition state.
- Mathur, Dwarka, L.,Agarwal, Anupma,Banerji, Kalyan K.
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p. 519 - 522
(2007/10/02)
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