Anionic polymerization of vinyl monomers with xanthates

Abstract

The polymerization of vinyl monomers with various xanthates (potassium tert‐butylxanthate, potassium benzylxanthate, zinc n‐butylxanthate, etc.) were carried out at 0°C in dimethylformamide. N‐Phenylmaleimide, acrylonitrile, methyl vinyl ketone, and methyl methacrylate were found to undergo polymerization with potassium tert‐butylxanthate; however, styrene, methyl acrylate, and acrylamide were not polymerized with this xanthate. In the anionic polymerization of methyl vinyl ketone with potassium tert‐butylxanthate, the rate of the polymerization was found to be proportional to the catalyst concentration and to the square of the monomer concentration. The activation energy of methyl vinyl ketone polymerization was 2.9 kcal/mole. In the polymerization, the order of monomer reactivity was as follows: N‐phenylmaleimide > methyl vinyl ketone > acrylonitrile > methyl methacrylate. The initiation ability of xanthates increased with increasing basicity of the alkoxide group and with decreasing electronegativity of the metal ion in the series, lithium, sodium, and potassium tert‐butylxanthate. The relative effects of the aprotic polar solvents on the reactivity of potassium tert‐butylxanthate was also determined as follows: diethylene glycol dimethyl ether > dimethylsulfoxide > hexamethylphosphoramide > dimethylformamide > tetrahydrofuran (for methyl vinyl ketone); dimethyl sulfoxide > hexamethylphosphoramide > dimethylformamide ≅ diethylene glycol dimethyl ether (for acrylonitrile).

Crosslinking of Starch Xanthate. V. Redox Grafting with Hydrogen Peroxide and Vinyl Monomers in Water

“…11, No.2, 1979 Since there is an excess alkali present, this possible side reaction is discounted. These observations broaden those of Dimov and Pavlov and provide a stronger base for eliminating possible side reactions to the main reaction of AN graft polymerization initiated by xanthated polysaccharide and leave reaction 5 as sole portrayal of our system. It is possible though that the mechanism of grafting could be considered as an anionic polymerization since we have used water as the solvent, which has a higher dielectric constant than any of the organic solvents which Yamaguchi, et a!., used.…”

“…5ROCSSNa+NaOH+25H202 +3(n+1)CH2=CHR'->3RO(CH2CHR')n CH2CH2R' + ROCSSSSCOR + 3Na2S04 +3H2S04+21H20+3C02 t (5) This final reaction reflects the predominance of the grafting reaction over crosslinking, in keeping with the analytical findings, and the product can be visualized as were color loss and slight turbidity development but no heating, gas evolution, or precipitation in either xanthate and AN or xanthate and H202 mixtures, although the pH in the latter fell to 2.6-3.8 within the first hour, correlating indirectly with the xanthate D. S. These pH levels are consistent with an oxidative pathway of peroxide, without excess alkali present, on a xanthate as per eq 6.…”

Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes

“…Based on these observations, we decided to revise our experimental procedure for the synthesis of MIC·CS 2 zwitterions by using a mixture of NaO t -Bu and CS 2 from the onset of the reaction in THF at 60 °C. These two reagents were added in large excess to compensate for the possible formation of sodium O - tert -butyl xanthate [ 72 – 74 ]. We reasoned that these conditions should favor a quantitative deprotonation of the starting triazolium salts and the concomitant trapping of the free carbenes by CS 2 prior to their potential decomposition.…”

The Alkali Metal Salts of Methyl Xanthic Acid

“…tively sparingly characterized, and the CSD [10] contains not more than two sodium xanthates and five potassium xanthates. Lithium xanthates are only briefly mentioned in the previous literature [21] and have never been characterized in detail to the best of our knowledge. Regarding the heavy alkali metals, the literature holds one very brief report on the crystal structure of Rb(SSC-OEt), [16] and caesium xanthates seem to be entirely unknown so far.…”