Studies on the Water-Soluble Polymers. X. Copolymerization of Maleic Acid or Fumaric Acid with Acrylamide. Seishi MACHIDA* and Hiroshi NARITA* Copolymerization of acrylamide (AA) with maleic acid (MA) or fumaric acid (FA) in dimethylformamide was investigated. The monomer reactivity ratios in the copolymerization were determined and the Q and e values were calculated as follows; for AA(1)-MA(2) r1=12.8, r2=0.01; Q2=0.095, e2=2.31 for AA(1)-FA(2) r1=7.0, r2=0.09; Q2=0.081, e2=1.53The difference in reactivity between MA and FA was discussed from the stand-point of their configurations.
Gamma-alumi na has proved to serve as an effective and durable catalyst for the reaction between hydrogen sulfide and methyl alcohol. No change in crystalline structure was observed in the used catalyst by the X-ray diffraction tests. The reacton velocity was extremelyhigh and thus was affected to a great extent by the particle size of the catalyst. When alumina was used as catalyst, rough chemical equilibrium seemed to be attained between methyl mercaptan and dimethyl sulfide. With cadmium sulf ide-alumina catalyst, the product mixture was rich in methyl mercaptan than when alumina was used. Aalumina-thoria catalyst was as active as alumina, and silica was less activ.
Vapor phase reaction of hydrogen sulfide with methyl alcohol over gamma-alumina to form methyl mercaptan and dimethyl sulfide was studied at 330, 370, 410, and 450°C; under pressures of 1, 4, and 5 kg/cm2; and in the mole ratios of hydrogen sulfide to methyl alcohol of 1 and 5. When the reaction was conducted above 400°C, formation of a small amount of permanent gases was observed. Below 400°C, however, the product consisted practi-cally of dimethyl ether, methyl mercaptan, dimethyl sulfide, and water. As the contact time was Prolonged, the amount of product dimethyl ether reached its maximum and then raduallv decreased to zero. Methyl mercaptan and dimethyl sulfide seemed to be formed simultaneously on the catalyst surface. The apparent activation energies were 10 kcal/mol as calculated based on the reaction rate of methyl alcohol, and 25 kcal/mol as cal-culated based on the rate of formation of methyl mercaptan and dimethyl sulfide.
The relation between methyl mercaptan and dimethyl sulfide, two product com-pon entsobtained from the vapor phase reaction of hydrogen sulfide and methyl alcohol over gamma-alumina catalyst, agreed with the equilibrium calculated from the equation 2 CH3SH CHCH3SCHCH3+HCH2S, assuming that Kp is 1.57 at 370°C. The true equilibrium states were confirmed by carrying out the reaction from both sides of the equation. A 2.2 kcal difference was noted in the value of free energy of formation of the reaction between the value calculated from the measured equilibria and that reported in the literature. This may be attributed to the probable errors in estimating the heat of formation of methyl mercaptan and dimethyl sulfide. The velocity of formation of methyl mercaptan and dimethyl sulfide from hydrogen sulfide and methyl alcohol over gamma-alumina catalyst of 2 mm diameter at 390°C was shown as follows:
Mechanism of the reaction between hydrogen sulfide and methyl alcohol over gamma-alumina catalyst can be shown as follows : The rate determining steps are (1) chemical absorption of methanol to the catalyst surface, and (2) surface reaction of surface methoxyl compound formed by abso-rption with absorbed hydrogen sulfide. When the formation of dimethyl ether is high, the principal rate determining step is (2); when the formation of dimethyl ether is negligible, the principal rate controlling step is (1).