These comparisons suggest that the low value of k2"/k, for reaction of pNPDPP with OHis caused by a relatively deeper penetration of this substrate into the micelle as compared with that of DNCB. A similar conclusion has been made for reactions in functional micelles.53 Values of kz"/kw for reactions of DNCB with phenoxide ion and pNPDPP with aryloxide and oximate ions are close to ~n i t y , 3~~p~~v~~ probably because the hydrophobicities of substrates and nucleophiles are such that both reside in the same region of the micelle.% Similar conclusions have (53) Bunton, C. A. in ref 32, Vol. 2, p 519. Bunton, C. A.; Sepulveda, L. Isr. J. Chern. 1979, 18, 298. (54) The second-order rate constants for reactions of several nonionic nucleophiles in the micellar pseudophase are smaller than in but these rate differences are understandable in terms of the lower polarity of the Stern layer as compared with water.Sb,S6
The adsorbed state of water on TiO2 was studied by temperature programmed desorption (TPD) in the range 0–1000 °C. Pure anatase and rutile samples, the TPD spectra of water from which were not affected by any contaminant, could be obtained by the hydrolysis of titanium oxalate and tetrachloride solutions, respectively. Two desorption peaks were observed for anatase with the peak maxima at 69–127 (I) and 191–256 °C (II), and three for rutile at 32–90 (I), 188–265 (II), and 310–356 °C (III). The sum of adsorbed amounts for peaks II, and III are within a monolayer coverage, that of peak I exceeding it. The enthalpies of adsorption were evaluated to be 36 and 55–69kJ·mol−1 for peaks I and II of anatase, and 36, 64, and 104 kj·mol−1 for peaks I, II, and III of rutile, respectively. From these results, the corresponding adsorbed species of peak I was tentatively assigned to physical adsorption, that of peak II to chemisorption on surface oxygen ion by hydrogen bond, and that of peak III to chemisortpion on Ti4+ by the coordination of oxygen atom of water molecule. The last species may be dissociated into surface OH groups.
synopaisThe monomer reactivity in the complexed copolymerization of vinyl compounds with alkylaluminum halides has been extensively surveyed. Equirnolar copolymers were obtained in various combinations of monomers which are classified into two monomer groups, A and B. The group B monomers are conjugated vinyl compounds having nitrile or carbonyl groups in the conjugated position and form complexes with alkylaluminum halides. The group A monomers are donor monomers having low e values, such as olefins, haloolefins, dienes, and unsaturated esters. These A monomers belong to the same group of monomers which give alternating copolymers in conventional radical copolymerization with rnaleic anhydride, SOz, and so on. In addit.ion the complexed copolymerization has the same specific characteristics as the conventional alternating copolymerization, i.e., high reactivities of allyl-resonance monomers and inner olefins and no transfer of halogen atom to the copolymers in CCl,. These features suggest little or no participation of the A monomer radical. The &-e scheme is also discussed in terms of the monomer reactivity. More than two monomers selected from groups A and B give multicomponent copolymers in which alternating sequential structures hold with respect to A and B. Anomalous mutual reactivities between two B monomers in the terpolymerization were observed and indicate that the nature of radical in the complexed copolymerization may be different from that expected by the Lewis-Mayo equation. The complexed radical mechanism previously proposed is discussed in connection with the specific behavior mentioned above.
EXPERIMENTAL
MaterialsMonomers. Ethylene, propylene, butadiene, vinyl chloride, and acrylonitrile were polymerization-grade reagents of the Sumitomo Chemical
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