1287a.    GUNDERMANN, E.  [Residues From Distillation of Synthetic Fatty Acids (Oxide Pitches).]  Bitumen, Terre, Asphalte, Peche, vol. 5, 1951, pp. 114-117; British Abs., 1951, B, I, p. 1202.

          In Germany fatty acids are produced by oxidation of Fischer-Tropsch slack wax (b. p. >350°) containing the maximum amount of C₂₅-C₃₅ paraffins.  The oxidized product contains 30-35% of mixed fatty acids and aldehydes, alcohols, dicarboxylic acids, ketones.  The complex mixture of acids is separated by conventional methods and fractionally distilled in a vacuum into C₄-C₉ fatty acids and C₁₀-C₂₀ (soap) fatty acids.  The residue of oxide pitch (7-15% of the original mixture) resembles tar or pitch; extensive distillation does not produce a hard pitch.  The material reacts with S to form materials of high molecular weight, the rise in softening point depending on the amount of S, reaction time and temperature; the maximum reaction temperature is 190°-200°.  With 10% of S, polymerization mainly occurs; with 20% of S, crosslinking with combination of S takes place and infusible products are formed.  Addition of 5% of 62% HNO₃ to oxide pitch has a pronounced polymerizing effect.  The S and HNO₃ products of the pitch are gummy and tough but are not hard.