“…Similar polymerization of ethylene carbonate leads to ether linkages due to loss of carbon dioxide 103 Organocatalytic Retention of thiocarbonyl 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD, organocatalyst) and 4-methyl benzyl alcohol (initiator) 104 Proceeds via retention of the thiocarbonyl bond, without an S-O isomerism, different to 17, reportedly due to the use of an organocatalyst; 18a was shown to polymerize the fastest due the additional ring strain of the trans configuration of the xanthate ring; 18b was thought to be faster than 18c due to C-S bonds being weaker and easier to break than C-O bonds Organocatalytic S-O isomerism BEMP, r.t 105. Produces only the thioester polymer, through an irreversible mechanism; similar to the DBU ringopening of ε-thionocaprolactone 16, however no trace of the thionoester is found Organocatalytic Retention of thiocarbonyl DMAP, DBU, thiourea106 …”