Pulping reactions

Pulp reaction to a polycarboxylate cement in monkeys. Journal of Dental Research, 53, 15-19. 

Manley, E. B. (1943). Pulp reaction to dental cements. Proceedings of the Royal Society of Medicine, 36, 488-99. 

Qvist, V. (1975). Pulp reactions in human teeth to tooth coloured filling materials. Scandinavian Journal of Dental Research, 83, 54-66. 

Stanley, H. R., Swerdlow, H. Buonocore, M. G. (1967). Pulp reactions to anterior restorative materials. Journal of the American Dental Association, 75, 132-11. 

Quinone methides formed during, for example, alkaline pulping reactions may have other mechanisms for rearomatization. Most commonly, in 8-0-4-, 8-5-, and 8-8-quinone methides QM1-QM3 (Fig. 12.2), retro-aldol elimination of formaldehyde to give styryl aryl ethers or stilbenes is common.40 Retro-aldol reactions using a strong base, for example, diazabicycloundecene (DBU) in CH2CI2 can also provide these compounds conveniently at room temperatures.41 3... 

The addition of anthraquinone (a chemical catalyst produced from coal tar) to the pulping liquor has been shown to speed up the kraft pulping reaction and increase yield by protecting cellulose fibers from degradation. The anthraquinone accelerates the fragmentation of lignin, allowing it to be... 

The kinetics of the delignification are of importance especially when considering the control of the pulping process. Since kraft pulping follows simpler kinetics than the sulfite processes, more applications have been adopted for this case. Because of the heterogenity of the system, however, pulping reactions are complicated and can therefore not be treated in the same fashion as homogeneous reactions in solution. 

The process is conducted at the high pH in the presence of sodium sulfide, sodium hydrosulfide, and sodium hydroxide at 150-180°C for about 2 hours (Fig. 33.26). Along with the primary cellulose product, the process generates a solution containing dissolved lignin, most of the wood s hemicellu-loses, and spent pulping chemicals ( black liquor ). This solution is used in the kraft recovery boiler as a source of power for the mill and fuel for chemical recovery operations crucial to economic operation. The chemistry of pulping reactions has been the subject of much study, and summaries are available the literature.425 127... 

The drastic changes cansed by pulping reactions are outside the scope of this chapter. 

DR Dimmel, LF Bovee. Pulping Reactions of Vinyl Ethers. J Wood Chem Technol 13 583, 1993. 

S Hosoya, K Seike, and 1 Nakano. Bleaching of high yield pulp Reactions of quino-nes and quinone polymers with some reducing agents. Mokuzai Gakkaishi 22 314-319, 1976. 

The use of agricultural residues allows the integral use of biomass for production of materials with higher value. Pulping reactions generate cellulose that is destined for... 

From wood, the reaction gives a high yield of low molecular mass degradation products (monomers to trimers, with traces of higher products) and, after treatment, no lignin can be detected in the remaining wood material. Thioacidolysis, when applied to kraft pulps, on the other hand, in addition to monomers-trimers also results in the presence of polymeric material formed as a consequence of pulping reactions [20]. 

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