El Paso Products Company

William D Nash

Ray N Finch

This invention provides a process for improving the recovery of byproducts associated with the isolation of C.sub.4 -C.sub.6 dicarboxylic acids contained in a waste byproduct stream, wherein the byproduct stream is derived from an adipic acid manufacturing operation involving nitric acid oxidation of a cyclohexanone/cyclohexanol feedstream. The main byproducts which are isolated are high purity dimethyl succinate, dimethyl glutarate and dimethyl adipate. Monomethyl esters of these dicarboxylic acids are recovered and recycled in the process.

Treatment of waste stream from adipic acid production

Freezing and melting techniques are described for separating 1,3-butadiene from a mixture of four-carbon compounds by fractional freezing of the liquid mixture and by fractional melting thereof. It has been discovered that when a frozen four-carbon mixture (BB) containing about 36% 1,3-butadiene (BD) is initially frozen, the first frozen fraction of up to about 30% of the mixture is enriched about 80% over the feed sample while the filtrate is decreased in BD about 36%. A second fractional crystallization of the melt and of the filtrate shows continued enrichment and impoverishment as to BD content, respectively. It has also been discovered that when a solidly frozen BB mixture is slowly thawed and the melt is progressively removed, the melt becomes markedly enriched in BD. A continuous fractional crystallization process that uses these discoveries for producing BD at purities greater than 99% is described. Utilizing liquefied natural gas (LNG) as the cryogen source for this process is also suggested, so that the refrigeration need for fractional crystallization of BB can be combined with the heating need for LNG vaporization.

Recovery of 1,3-butadiene by fractional crystallization from four-carbon

The known compound 2-hydroxy-3-methyl cyclopent-2-ene-1-one, used as a flavor imparting agent and commonly called maple lactone, is synthesized by a modified acyloin condensation of esters of 2-methyl glutaric acid in which oxygen is introduced in a specific manner to the reaction system.

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Odessa, TX, United States of America

William D Nash