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H NMR chemical shifts d OH of the proton in the hydroxyl group of n-butanol and tert-butanol have been measured as function of mixture composition in the binary mixtures n-butanol + cyclohexane, tertbutanol + cyclohexane, and n-butanol + pyridine at 303, 313 and 323 K. In addition the molar excess enthalpy H E of n-butanol + pyridine has been determined as a function of the mixture composition at 298 K using a flow calorimeter. The ERAS (extended real associated solution) model has been applied for describing simultaneously the data of d OH and H E for n-butanol + cyclohexane accounting for self association of n-butanol via hydrogen bonding. The mixture of n-butanol + pyridine was treated similarly using the ERAS model considering self association of n-butanol as well as cross association of n-butanol with pyridine. The results obtained indicate that self association in n-butanol and tert-butanol as well as cross association between n-butanol and pyridine play an important role in these mixtures. The ERAS model is able to describe the dependence of d OH and H E on mixture composition and temperature for all mixtures with a minimum of adjustable parameters providing a realistic insight into the liquid structure of these systems.y Electronic supplementary information (ESI) available: Experimental chemical shifts d OH of alcohol mixtures referred to TMS (Table S1) and molar excess enthalpies H E of n-butanol(1) + pyridine(2) mixtures at 298 K (Table S2). See

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The standard molar enthalpies of vaporization ∆ l g H°m of 1-methylcyclohexene, 4-methylcyclohexene, 2,4-dimethyl-2-pentene, cis-2-heptene, trans-4-octene, 1-nonene, 2,6-dimethylheptene, 1-undecene, trans-2,2,4,6,6-pentamethyl-3-heptene, and cis-2,2,4,6,6-pentamethyl-3-heptene at the temperature T ) 298.15 K were obtained from the temperature dependence of the vapor pressure measured by the transpiration method. The values of ∆ l g H°m(298.15 K) for these compounds and additionally for 3-methylcyclohexene were also measured using the correlation gas-chromatography method. The results from both methods are indistinguishable within the experimental uncertainties of less than (0.5 kJ‚mol -1 . Results from this work together with the data available from the literature were used to derive correlations for the prediction of the standard molar enthalpies of vaporization ∆ l g H°m(298.15 K) of monoolefins with linear and branched hydrocarbon chains.

(3‐Hydroxy‐1‐propenyl)tris(trimethylsilyl)silanes (Me3Si)3SiCH=CHCR2OH (8b,c) (b: R = Me; c: R = Ph) undergo a rapid rearrangement involving a 1,2‐Si,C migration of one trimethylsilyl group from the central silicon atom to a cationic neighboring carbon atom and a shift of the olefinic double bond, in the presence of acid, to afford (1‐trimethylsilyl‐2‐propenyl)bis(trimethylsilyl)silanols (Me3Si)2Si(OH)CH(SiMe3)CH=CR2 (13b,c). Treatment of 8b,c with sulfuric acid in methanol gives the methoxysilanes (Me3Si)2Si(OMe)CH(SiMe3)CH=CR2 (14b,c). In a related reaction, 8b,c are converted by boron trifluoride into the fluorosilanes (Me3Si)2SiFCH(SiMe3)CH=CR2 (15b,c). A possible mechanism of the isomerization reaction, involving the rearrangement of the silylcarbenium ions [(Me3Si)3SiCH=CHCR2]+ into the silylium ions [(Me3Si)2SiCH(SiMe3)CH=CR2]+, is proposed. This is supported by calculations, which indicate the higher stability of the silylium ion 10b compared with the isomeric silylcarbenium cation 9b. For 14c the results of an X‐ray structural analysis are given.

Keywords: Silenes / Ab initio calculations / Donor-acceptor systems Ab initio calculations were performed to predict geometric structures, stabilizing energies and rotational barriers of some intramolecularly donor-stabilized silenes. Calculations were performed using the HF, MP2, and B3LYP method with the 6-31G(d) and 6-31++G(d,p) basis set. Results were compared to experimentally available X-ray structures and energy barriers known from temperature dependent 1 H NMR