Regioselective [3+3] Cyclization of 1,3‐Bis(silyloxy)buta‐1,3‐dienes with 1,1,1‐Trifluoro‐4‐(silyloxy)alk‐3‐en‐2‐ones: New and Convenient Synthesis of Functionalized 5‐Alkyl‐3‐(trifluoromethyl)phenols

Functionalized 5‐alkyl‐3‐(trifluoromethyl)phenols were prepared by formal [3+3] cyclization of 1,3‐bis(silyloxy)buta‐1,3‐dienes with 1,1,1‐trifluoro‐4‐(silyloxy)alk‐3‐en‐2‐ones derived from 1,1,1‐trifluoroalkane‐2,4‐diones. The latter were prepared by condensation of the dianion of 1,1,1‐trifluoropentane‐2,4‐dione with alkyl halides.     

Synthesis of poly(glycidol)‐block‐poly(N‐isopropylacrylamide) copolymers using new hydrophilic poly(glycidol) macroinitiator

New, water soluble poly(glycidol) (PGl) macroinitiators for atom transfer radical polymerization (ATRP) were synthesized. This new class of macroinitiators were prepared in a three‐step process. First, series of well‐defined ω‐hydroxyl functional poly(glycidol acetal)s with different molecular weights was synthesized via anionic polymerization followed by quantitative termination of anionically growing active sites. End capping was achieved by treatment of living chain ends with water. The living nature of the system and termination reaction is discussed. In the second stage, monofunctional poly(glycidol acetal)s were functionalized by esterification with 2‐chloropropionyl chloride. Finally, selective deprotection (hydrolysis) of acetal protective groups was performed. As simultaneous partial cleavage of ester bond of attached ATRP moieties was unavoidable, the final functionality of macroinitiator calculated from ¹H NMR varied in the range 85–95%. The obtained (2‐chloropropionyl) poly(glycidol) macroinitiator with DP = 55 and 90% functionality was successfully used in ATRP polymerization of N‐isopropylacrylamide (NIPAAm) at room temperature in the DMF/water mixture. Linear block copolymers with relatively narrow molecular weight distribution and controlled composition were obtained and characterized with ¹H NMR and SEC‐MALLS measurements. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2488–2499, 2008     

Dynamics of adiabatic electron transfer reactions at metal electrodes

We have investigated the dynamics of adiabatic electron transfer reactions at metal electrodes using a Hamiltonian suggested by Schmickler (J. Electroanal. Chem., 204 (1986) 31). We show that in the adiabatic limit the problem reduces to that of dynamics of a single variable, the shift of the ionic orbital caused by its interaction with the solvent. This variable is identified as the reaction co-ordinate for the problem and we show that in certain limits, it obeys a non-linear Volterra type integral equation, with a stochastic inhomogeneous term. For an inhomogenous term with the autocorrelation function decaying exponentially, this may be converted into a differential equation for Brownian motion. This equation can be analysed to obtain the rate, through the associated Fokker-Planck equation. The rate so obtained, has a correction to the pre-exponential factor obtained by Schmickler. A possible extension to inner sphere reactions is also discussed.     

Frequency tripling for resonance ionization spectroscopy (RIS) of Cd

1 =228.8 nm). Laser light with an average power of 2 mW was obtained after frequency tripling and was successfully used for RIS test measurements on cadmium with a time-of-flight mass spectrometer. The eight stable Cd isotopes could be identified unambiguously. Received: 6 October 1997     

An intercomparison of rotational loss measurements in non-oriented Fe–Si alloys

We report a comparison of rotational energy loss measurements in the same non-oriented Fe–Si laminations carried out by two laboratories Istituto Nazionale di Ricerca Metrologica (INRiM) in Torino, Italy and Wolfson Centre for Magnetics (WCM) in Cardiff, United Kingdom. The measurements were performed on disk samples at magnetizing frequencies between 5 and 200 Hz with controlled circular flux density loci ranging between 0.2 and 1.9 T. Energy loss was measured applying both the fieldmetric and the rate-of-rise of temperature methods. The latter, exploiting the rate of rise of temperature under quasi-adiabatic conditions, is conveniently adopted on approaching magnetic saturation. Results from the two laboratories agree well up to 1.4 T, despite the different physical principles of the fieldmetric vs. rate-of-rise of temperature methods and the different size of sample and measuring areas. The rate-of-rise of temperature method seems to be the natural approach at high induction values.     

Null Controllability for the Dissipative Semilinear Heat Equation

We consider the exact null controllability problem for the semi- linear heat equation with dissipative nonlinearity in a bounded domain of Rⁿ . The main result of the article asserts that if the nonlinearity is even mildly superlinear, then global null controllability in an arbitrarily short time fails; instead we provide sharp estimates for the controllability time in terms of the size of the initial data.