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6593348 
Journal Article 
SYNTHESIS OF THE MONOMERIC ANTIOXIDANT - 3,5-DI-TERT-BUTYL-4-HYDROXY-STYRENE BY THE THERMAL-DECOMPOSITION OF TRANS-3,5-DI-TERT-BUTYL-4-HYDROXYCINNAMIC ACID 
Munteanu, D; Csunderlik, C; Tincul, I; , 
1991 
JOHN WILEY & SONS LTD 
W SUSSEX 
37 
2 
411-426 
English 
WOS:A1991FT27100017 
The thermal decomposition of trans-3,5-di-tert-butyl-4-hydroxy-cinnamic acid (BHC) in the solid state, in aqueous solution and in solutions in organic solvents was studied in order to develop a preparative method for the synthesis of the monomeric antioxidant 3,5-di-tert-butyl-4-hydroxystyrene (BHS). Thermal methods of analysis showed that, during the solid-state decomposition of BHC, its decarboxylation was accompanied by desalkylation and polymerization of the styrenic decomposition products. BHC decarboxylation is aqueous solution was also accompanied by polymerization. A kinetic study of BHC decomposition in organic solvents by H-1-NMR spectrometry revealed that only the decomposition of BHC in aprotic dipolar solvents such as dimethylsulphoxide and dimethylformamide, at temperatures lower than 150-degrees-C, could be used as a preparative method for the synthesis of BHS. The decarboxylation of BHC took place by zero-order kinetics through a mechanism involving the ionization of BHC in the aprotic dipolar solvent. The reaction rate increased drastically with increasing solvent polarity and in the presence of trace amounts of BHC sodium salt. Both monomeric antioxidants, i.e. BHS and BHC, may be used to obtain polymer-bound antioxidants, e.g. by melt-grafting onto polyethylene.