Polymeric structure of coal. 2. Structure and thermoplasticity of sulphur-rich Ra?a lignite

The methods of reduction and reductive alkylation with potassium in tetrahydrofuran and sodium in liquid ammonia have been applied to sulphur-rich, highly fluid (in carbonization) Ra?a lignite. The results indicate that solubilization of coal by alkylation of the coal anion formed in liquid ammonia is a clean and defined process. It is concluded that the highly thermoplastic properties of Ra?a coal result mainly from cleavage of CSC(COC) bridges, low contents of OH and lack of SH groups. In contrast to ‘normal’ bituminous coals investigated until now and characterized by wide distribution of the molecular weight of clusters formed on cleavage of ether bridges, about 80% (w/w) of Ra?a lignite is built of units of almost uniform molecular weight (MW 500).