No abstract

The rates of reaction of various alkyl chlorides (i) in 80 :,& ethanol and (ii) in almost absolute formic acid, have been measured conductometrically .For the reactions in 80 yo ethanol, the AH+ and 4S* values have been obtained.The results are briefly discussed.were made. The thermostat temperatures were held constant to within 0.01 " C, and checked by N.P.L. standardized thermometers. The initial concentration of RCl in these experiments was usually of the order of 0 -2 mole/l.Materials .-ETHYL ALcoHoL.-Absolute ethyl alcohol was refluxed with calcium oxide and distilled. FORMIC AcID.-Hopkin and Williams' go yo A.R. formic acid was subjected to fractional crystallization. Eight crystallizations gave an acid of m.p. 8.2' C. CARBON TETRACHLORIDE.-Albright and Wilson's CCI, was distilled h-Om CaCl, ; b.p. 77" C/760 mm. BENZAL CHLORIDE.-B.D.H. C,H,CHC12 was vacuum-distilled from CaC1, ; b.p. 85' C/II mm. BENZOTRICHLORIDE.-B.D.H. C,H,CCl, was fractionated under reduced pressure ; b.p. 101' C/15 mm. BORNYL CHLoRIDE.-Kahlbaum's C,,H,,Cl was sublimed under reduced pressure.No data were available for the conductivity of HCl in 80 yo ethanol.

We have studied the ESR spectra of methanol solutions of the radical cation (1) of ethylquat (1,1 '-diethyl-4,4'-bipyridylium diiodide) from +30 to -90 °C. The values of the splitting constants obtained at -80 °C are /I(pyridyl N) 0.414, A (pyridyl H(3)) 0.164, A (pyridyl H(2)) 0.136, A (NCH2) 0.232, and ^(CHj) 0.007 mT. Proton hyperfine splitting constants have been determined using electron-nuclear double-resonance (ENDOR) spectroscopy. Assignments of the splitting constants were made by reference to the paraquat radical cation and computer simulation showed excellent agreement. On decreasing the temperature the concentration of the radical cation decreases until at -90 °C the ESR signal intensity is very low. This process is reversible and concentration studies indicate that the radical cation is in equilibrium with a diamagnetic dimer species. AH°for this equilibrium is found to be -8.19 ± 0.4 kJ mol-1. The AG°and AS°values at 25 °C are -15.94 kJ mol-1 and +26.01 J mol-1 K-1, respectively.

Butyl-lithium with 1,l-diphenylethylene in benzene gives the ion pair BuCH,CPh,-Li+, which has an absorption peak a t 428 mp (E 1-6 x 104).The order of this reaction is unity in 1,l-diphenylethylene, and 0.18 in butyllithium. Since it is known that butyl-lithium is highly associated (some six-fold) in benzene, we interpret the low order in this reagent by assuming (i) that equilibrium in this association lies well towards the associated side, and (ii) that only monomeric butyl-lithium reacts with 1,l-diphenylethylene.Butyl-lithium does not react with 1,1,3,3-tetraphenylbut-l-ene or with tetraphenylethylene, although both these olefins give carbonium ions with dilute acids. We assume that steric hindrance here inhibits formation of an anion by addition of a butyl group. THE action of cationic catalysts on 1,l-diphenylethylene was studied earlier; 1 we have extended this work to anionic catalysts. Following a preliminary communication 2 this paper gives a detailed account of the spectrophotometric part of this work. EXPERIMENTALApparatus.-The apparatus used was of all-glass construction, without taps. Contamination with tap grease or air was impossible. The glass was cleaned by soaking it for a few minutes in concentrated nitric acid, followed by a rinse with water and a soaking for some minutes in 5% aqueous sodium hydroxide; it was then washed in a stream of water for a t least an hour, and after a final rinse with distilled water was dried in an oven at 120". Each piece of apparatus was baked under a high vacuum for a t least 3 hr. before contact with any of the reagents.

The heats of polymerization of acrylic acid, methyl acrylate, methacrylic acid, and methyl methacrylate have been measured. Values for the heat of polymerization of unstrained polymer molecules have been calculated, and the low heat of polymerization of methyl methacrylate has been attributed to the presence of steric hindrance in the polymer molecule.