Hydroxybutyric acid, conversion lactone

One of the classic examples of a reversible reaction that is first-order in both directions is the conversion of y-hydroxybutyric acid into its lactone in aqueous solution. 

One of the classical examples of a reversible reaction is the conversion of y-hydroxybutyric acid into its lactone in an aqueous solution. In aqueous solution, the water concentration may be considered constant, so the reverse reaction follows pseudo-first-order kinetics. The following data were obtained. Determine the values of both first-order rate constants (forward and reverse). The initial acid concentration is 182.3 mol/L. 

Example 5.1. Reversible formation of a lactone. Results obtained for the conversion of 7-hydroxybutyric acid into its lactone... 

Figure 5.4. Conversion of y-hydroxybutyric acid into its lactone, plotted as reversible first order-first order reaction (left) and as irreversible reaction of order 1.5 (right).

Consider the conversion of y-hydroxybutyric acid (A) into its lactone (L) in aqueous solution ... 

Five-membered, unsubstituted, lactone y -butyrolactone (y-BL) was polymerised by PPL or PCL [74, 81] into small oligomers with a DP of 8-11. More recently, y-BL have yielded homopolymers of up to 50,000 [82]. Poly(y-butyrolactone) is a very useful biomaterial, since its degradation gives y-hydroxybutyric acid, a metabolite naturally occurring in the body. In the PSL-catalysed polymerisation of y-valerolactone (y-VL) and y-caprolactone (y-CL), less than 10% conversion was observed at 60 °C for 480 h [76]. 

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