Transesterification of starch with methyl betainate was studied for the first time, both in aprotic media and solid state, under alkaline acidic conditions. Betaine hydrochloride esterified methanol, attaining a conversion 86%. Starch then converted into either N,N-dimethylformamide or dimethyl sulfoxide, using sulfuric acid as catalyst pre-activating polymer NaOH/ethanol. Furthermore, solid-st...