Mutarotation of Poly-L-proline

Abstract

THE synthesis and some of the properties of poly-L-proline were described recently¹. A sample with an average degree of polymerization n = 67 which was obtained by bulk polymerization, dissolved in glacial acetic acid and precipitated with ether, gave the following specific rotations: [α]²⁰_D −483° (c. 1.5 in formic acid), [α]²⁰_D −372° (c. 2.0 in glacial acetic acid) and [α]²⁰_D −353° (c. 2.0 in water). As will be shown however, the optical rotation of a solution of poly-L-proline depends both on the history of the sample and on the manner in which the solution was prepared.