Asphaltene sulfonic acids

Resin sulfonic acids Asphaltene sulfonic acids... 

It is not possible to dissolve the asphaltenes in water by treatment of the halo derivatives with aqueous sodium hydroxide or with aqueous sodium sulfite (II). The hydrolyzed products remained insoluble even in a strongly alkaline solution. The decreased (H + Cl)/C ratios and the increased O/C ratios of the products relative to those of the parent halo-asphaltenes indicate that partial reaction occurs. The infrared spectra of the products showed a broad band centered at 3450 cm 1, a region assigned to the presence of hydroxyl groups in the products, but it was not possible to establish conclusively the presence of sulfonic acid group(s) in the product from the sodium sulfite reaction by assignment of infrared absorption bands to this particular group. 

The organic component of black sulfuric acid is complex including sulfonic acids (37%), sulfonic ethers (8.4%), paraffin-naphthenic hydrocarbons (22.6%), mono- and polycyclic aromatic hydrocarbons (6.6% and 8.9%, respectively), resins (5.5%) and asphaltenes (11.0%). The organic component of black sulfuric acid is characterized by a wide boiling range and compounds with distillation temperature above250°C (Table 14.1). 

These sulfomethylated and sulfonated oxidized asphaltenes even remain in solution after acidification with 5% aqueous hydrochloric acid to a pH of 2.5-3.0 while the parent-oxidized asphaltenes can be precipitated from alkaline solution by acidification to a pH of 6.5. 

Herlem et al463 have observed that asphaltene is dissolved in fluorosulfuric acid and the process is accompanied by strong redox reactions (SO2 and HF evolution). The products are mainly functionalized by SO3H groups, but SO2F groups were also detected by XPS. Indeed, model studies with benzene showed the formation of benzenesulfonic acid, diphenylsulfone, and benzenesulfonyl fluoride. For alkylbenzenes, sulfonation was not accompanied by cracking of the alkyl chain. 

---