Abstract Poly(vinyl alcohol) (PVAc) composite porous membrane has been prepared from PVAc latex film by extraction with acetone. The PVAc latex was prepared by emulsion polymerization of vinyl acetate in the presence of PVA, employing the hydrogen peroxide–tartaric acid systemm as an initiator. The extraction degree of PVAc could be controlled in a wide range by changing the addition method of the initiator, and, acoordingly, PVA–PVAc omposite porous membranes which had variosu void volumes were obtained. The maximum void volume attained was ca. 90%. Permation characteristics of organic solvents wre investigated on the membranes whose extraction degrees were 95.6% and 80.7%. Thge feeds were benzene, n‐hexane, cyclohexane, and their mixtures. neither swelling nor shrinkage in tje appearance size of the while benzene hardly permeated even at 20 kg/cm 2 . The grafted PVAc in the mebrane was removed or converted into grafted PVA by treatment with sodium methylate, and then the depression of benzene permeation was lost. The grafted PVAc was suggested to be localizd on the cell wall and was found to function as a valve which closes with nenzene or a good solvent for PVAc and opens with n‐haxane or a poor solvent for PVAc.
Abstract As the basic research for the study of complex reactions in polymers, the complex formation of poly(vinyl alcohol) (PVA) with copper and other metals was tried. Spectroscopy, pH titration, and elementary analysis were employed in the reaction of PVA and Cu(II) ions in aqueous solution. The complexing protonation was found in the higher pH region (above 7.0), and the maximum absorptions at 640 and 260 nm were observed. These ϵ max were proportional to the concentrations of Cu(II) ions bound to the hydroxyl groups of PVA. Formation constants of the PVA–Cu(II) complexes were measured by applying a modified Bjerrum's method. The effects of the ratio Tcu 2+ /T HL , the anions in copper salts, and the degree of polymerization on the formation constants were studied. Four hydroxyl groups combined with one Cu(II) ion in the pH range above 7.0. The stability constants for the complexes of PVA with bivalent transition metallic ions were in agreement with the Irving‐William's series. The changes in viscosity, solubility, tacticity, mechanochemical phenomenon, and the other properties based on the complex formation are discussed.
cis-α,β-Unsaturated sulfoxides were predominantly formed in the Horner-Wittig reaction with bis(2,2,2-trifluoroethyl)phosphono sulfoxides and aromatic aldehydes, while the reaction of the corresponding sulfides showed trans- or lower cis-selectivity. The reduction of cis-α,β-unsaturated sulfoxides with tributylphosphine in carbon tetrachloride gave cis-vinyl sulfides with retention of stereochemistry.
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Various kinds of plasticizers such as dialkyl glycol ester were synthesized and tested as plasticizers of polyvinyl acetate films.Among these, as a result, dimethyl, diethyl glycol sebacate and dimethyl, diethyl, dibutyl glycol adipate had better plasticity effects and lower evaporation loss than the conventional dibutyl phthalate.
Photooxygenation of either (E,E)- or (E,Z)-1-aryl-1,3-pentadienes (1a−c) sensitized with tetraphenylporphine (TPP) in benzene gave almost all cis-endoperoxides (2a−c) (cis-3-aryl-6-methyl-1,2-dioxacyclohex-4-enes) in good yields. A time course study of photooxygenation of (E,Z)-rich dienes measured by 1H NMR showed that singlet oxygen added exclusively to (E,E)-dienes converted from (E,Z)-dienes by photoinduced isomerization, and both rates increased when electron-donating groups were attached to the aryl group. A concerted [4 + 2] cycloaddition mechanism is suggested by the exclusive formation of cis-endoperoxides from (E,E)-dienes, despite the small energy difference between cis- and trans-endoperoxides calculated by ab initio methods. Some experiments were made to explore the observed isomerization.
Following the discovery for a formation of 1-aryl-4-cyanopyrazole by the reaction of 2-(1-ethoxy-1-methoxymethyl)-3-ethoxypropionitrile (I) and arylhydrazine, the behavior of the nitrile group and the alkoxyl in 2-position in this condensation reaction was examined. The reaction of 2-(1-ethoxy-1-methoxymethyl) propionitrile (IV), 2-(1-ethoxy-1-methoxymethyl) propylamine (V), and 2-(1-ethoxy-1-methoxymethyl)-3-ethoxypropylamine (VI) with phenylhydrazine or p-nitrophenylhydrazine afforded 1-aryl-4-methyl-5-aminopyrazoles (XIII) and (VII) from (IV), 1-aryl-4-methylpyrazoles (XII and IX) from (VI), and (IX) from (V). The structure of these products was established from their infrared and ultraviolet spectra, and elementary analytical values. Deamination of (VII) by diazotization gives (IX), oxidation of (IX) with potassium permanganate gives 1-p-nitrophenyl-4-carboxypyrazole (X), nitration of (XII) gives (IX), and reduction of (IX) over palladium-carbon affords the amino compound (XI). These facts indicate the correctness of the structure of the reaction products (VII), (IX), (XII), and (XIII).Foregoing results indicate that the nitrile group in (IV) behaves in ordinary reaction type and the alkoxyl in (VI) does not take part directly in pyrazole condensation but acts toward aromatization. The compound (V) is somewhat less reactive than (VI) but both undergo cyclization to pyrazole compound accompanied by dehydrogenation. These facts are interesting in connection with results described in the preceding paper.
