Analysis of the telomerization of acrylic acid by mercaptans, 1 -: Telomerization of acrylic acid by thioglycolic acid;: Influence of the natural of the solvent on the value of the transfer constant and kp/kte1/2

The telomerization of acrylic acid (AA) with thioglycolic acid (TGA) initiated with 2,2'-azoisobutyronitrile (AIBN) was first investigated in organic medium (THF, 65 degreesC). The kinetic study of this telomerization led to the determination of the TCA transfer constant (C-r = 3.2) and to the ratio k(p)/rootk(te) equal to 0.48 L-1/2.mol(-1/2).s(-1/2). Then, the same study was performed both in aqueous medium and in water/THF mixture in order to investigate the solvent effect on the transfer constant. From these works it is emphasised that the nature of the solvent plays an important role on the kinetics parameters. First, this research underlined an increase of the k(p)/rootk(te) value by raising the water proportion in water/THF mixtures. Then, the kinetic study showed the highest value for the k(p)/rootk(te) constant, equal to 2.48 L-1/2.mol(-1/2).s-(1/2) when the telomerization proceeded in water. Consequently, the value of C-T, which is directly influenced by the k(p)/rootk(te) constant, presented a decrease from CT = 3.2 in THF to a value equal to 0.5 in water. By this way, the a ideal,, case of telomerization (C-T = 1) was reached for a mixture of solvents; 80% water/20% THF (v/v). [GRAPHICS]