Page 177 - Chemical and process design handbook

Speight_Part II_B 11/7/01 3:11 PM Page 2.118

BUTYROLACTONE

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γ-butyrolactone (dihydro-2,3H-furanone, boiling point: 204 C, density:
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1.129, flash point: 98 C) was first synthesized in 1884 by an internal ester-
ification of 4-hydroxybutyric acid. The principal commercial source of this
material is dehydrogenation of butanediol. The manufacture of butyrolac-
tone by hydrogenation of maleic anhydride is also a viable route.
Butyrolactone is completely miscible with water and most organic sol-
vents. It is only slightly soluble in aliphatic hydrocarbons. It is a good
solvent for many gases, for most organic compounds, and for a wide
variety of polymers.
Butyrolactone is used to produce N-methyl-2-pyrrolidinone and 2-pyrro-
lidinone, by reaction with methylamine or ammonia, respectively. Consider-
able amounts are used as a solvent for agricultural chemicals and polymers,
in dyeing and printing, and as an intermediate for various chemical syntheses.
Butyrolactone undergoes the reactions typical of γ-lactones. Particularly
characteristic are ring openings and reactions in which ring oxygen is
replaced by another heteroatom. There is also marked reactivity of the
hydrogen atoms alpha to the carbonyl group.
With acid catalysts, butyrolactone reacts with alcohols rapidly even at
room temperature to produce esters of 4-hydroxybutyric acid. The esters
can be separated by a quick flash distillation at high vacuum.
Butyrolactone reacts rapidly and reversibly with ammonia or an amine
forming 4-hydroxybutyramides, which dissociate to the starting materials
when heated. At high temperatures and pressures, the hydroxybutyramides
slowly and irreversibly dehydrate to pyrrolidinones; this dehydration is
accelerated by use of a copper-exchanged Y-zeolite or magnesium silicate.

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