The present invention describes an improved process for the industrial scale production of dimethyl fumarate. The process involves a one-pot ring opening reaction of maleic anhydride to monomethyl maleate and isomerization into the corresponding monomethyl fumarate in presence of a Lewis acid. Finally the mono methyl fumarate was converted into the dimethyl fumarate by an acid catalyzed esterification reaction.

The invention describes pharmaceutical compounds and compositions comprised of prodrug ligands attached to GHB (CNS drugs) in a manner that substantially decreases or deters the potential for GHB abuse, illicit and illegal use, and overdose. These compounds and compositions may provide substantially higher bioavailability, substantially higher half-life, substantially higher chemical and biological stability, and easier shipping and distribution requirements. These GHB prodrug compounds may alter both the physical and chemical properties and thus may not be suitable for illicit use as a date-rape drug (i.e., they may not dissolve instantly in water based drinks, may have different color once in solution, and/or may have a taste and odor once in solution etc.). When delivered at the proper dosage, the pharmaceutical composition provides therapeutic activity similar to that of the parent active agent GHB.

A process for recovering product dialkyl succinate, dialkyl maleate or dialkyl succinate and dialkyl maleate from an overhead stream from an esterification reaction column, said overhead stream comprising as a major component alkanol and water and as a minor component the product dialkyl succinate, dialkyl maleate or dialkyl succinate and dialkyl maleate which forms an azeotrope with the water, wherein said process comprises washing the overhead stream with butanol.

A process for recovering product dialkyl succinate, dialkyl maleate or dialkyl succinate and dialkyl maleate from an overhead stream from an esterification reaction column, said overhead stream comprising as a major component alkanol and water and as a minor component the product dialkyl succinate, dialkyl maleate or dialkyl succinate and dialkyl maleate which forms an azeotrope with the water, wherein said process comprises washing the overhead stream with butanol.

A salicyl fumarate derivative, and its general structural formula (A) is:

##STR00001##

Wherein the structural formula (A), R.sub.1 is one of H.sup.+, Na.sup.+, K.sup.+ or NH4.sup.+. R.sub.2 is one of fumaric acid ester products. It has the general structural formula of the combination of salicylic acid and fumaric acid through esterification reaction. This category of compounds possesses good effects in treatment of neurodegenerative diseases.

A salicyl fumarate derivative, and its general structural formula (A) is:

##STR00001##

Wherein the structural formula (A), R.sub.1 is one of H.sup.+, Na.sup.+, K.sup.+ or NH4.sup.+. R.sub.2 is one of fumaric acid ester products. It has the general structural formula of the combination of salicylic acid and fumaric acid through esterification reaction. This category of compounds possesses good effects in treatment of neurodegenerative diseases.

A salicyl fumarate derivative, and its general structural formula (A) is:

##STR00001##

Wherein the structural formula (A), R.sub.1 is one of H.sup.+, Na.sup.+, K.sup.+ or NH4.sup.+. R.sub.2 is one of fumaric acid ester products. It has the general structural formula of the combination of salicylic acid and fumaric acid through esterification reaction. This category of compounds possesses good effects in treatment of neurodegenerative diseases.

A process for carrying out a reaction in a reaction column, said process comprising: providing a first reactant to the reaction column in the liquid phase; contacting said first reactant with an excess of a second reactant such that reaction takes place within the reaction column to form a low boiling product and a high boiling product, at least a portion of said second reactant being provided to the reaction column in the vapour phase; recovering an overhead stream from at, or near, the top of the reaction column, said overhead stream comprising unreacted second reactant and the low boiling product; and recovering a bottoms stream from at, or near, the bottom of the reaction column comprising the high boiling product; wherein at least a portion of the heat required to vaporise the second reactant provided to the reaction column in the vapour phase is provided by heat exchange in a heat exchanger with a hot stream generated within the process other than a hot stream generated within the reaction column.

A process for carrying out a reaction in a reaction column, said process comprising: providing a first reactant to the reaction column in the liquid phase; contacting said first reactant with an excess of a second reactant such that reaction takes place within the reaction column to form a low boiling product and a high boiling product, at least a portion of said second reactant being provided to the reaction column in the vapour phase; recovering an overhead stream from at, or near, the top of the reaction column, said overhead stream comprising unreacted second reactant and the low boiling product; and recovering a bottoms stream from at, or near, the bottom of the reaction column comprising the high boiling product; wherein at least a portion of the heat required to vaporise the second reactant provided to the reaction column in the vapour phase is provided by heat exchange in a heat exchanger with a hot stream generated within the process other than a hot stream generated within the reaction column.

Aqueous compositions containing 6-undecanol-esters are useful in cosmetic aplications. Methods for producing 6-undecanol-esters are also provided.