Published March 1969
This report deals with the processes for preparing the three isomers of cresols, as well as with products with cresols as main constituents, commercially known as cresylic acid. Until now, cresols were recovered mainly from petroleum refinery waste and coal tar, with only a minor part from synthesis sources. How- ever, with increasing demand and limited supply from these by-product sources, the synthesis process will increase in importance. This report deals primarily with the synthesis processes, although the processes for recovery of cresols and cresylic acids from petroleum refinery waste and coal tar also are evaluated as a basis of comparison.
Three commercial synthesis processes--alkylation, sulfonation, and cymene-- are evaluated. Each can be varied to produce different isomer distribution of products. These variances are discussed and compared. Other synthesis processes are reviewed and in some cases briefly evaluated. m-Cresol and p-cresol very often occur together and are difficult to separate. The various separation processes are described and discussed.
One process involving butylation and separation and followed by dealkylation is evaluated. This process produces m-cresol and ditertiary butyl p-cresol. The bases for these designs and costs are given in Appendix A, the physical data in Appendix B, and product specifications in Appendix C. Appendix D covers the treatment of phenolic waste water.
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