Synthesis and polymerization of racemic and optically active β‐substituted β‐propiolactones. III. β‐monosubstituted monomers and polymers

Abstract

Optically active β‐(1,1‐dichloroethyl)‐β‐propiolactone (CH3CCl2‐PL), β‐(1,1‐dichloropropyl)‐β‐propiolactone (C2H5CCl2‐PL), and β‐(1,1‐dichlorobutyl)‐β‐propiolactone (C3H7CCl2‐PL) were synthesized with enantiomeric excesses of 100, 100, and 84%, respectively. Polymerization was conducted in bulk and toluene solution, under vacuum, using mainly ZnEt2/H2O as initiator. Osmometry analyses indicate molecular weights in the range 10,000–25,000. The polymers thus prepared are semi‐crystalline and show large optical rotation values.13 C‐NMR was used to show that they have a high degree of isotacticity, indicating that little or no racemization occurs in the course of polymerization. Glass transition, melting and decomposition temperatures are given as a function of the size of the substituent, and their variations are discussed.

Structure and morphology of poly(?-hydroxybutyrate) synthesized by ring-opening polymerization of racemic (R,S)-?-butyrolactone with distannoxane derivatives

“…The reactor was heated in silicone bath at 80 °C under vacuum for 6 h. The monomer was added by syringe after the reactor had cooled to room temperature. The contents of the ampoule were degassed using three freeze–thaw cycles and finally sealed under vacuum 6. 8, 12 The solution was warmed to room temperature and stirred magnetically.…”

“…The synthesis of poly(β‐hydroxybutyrate) (PHB) from ( R,S )‐β‐butyrolactone (β‐BL) is used as a route to the preparation of stereochemical and structural isomers of this polyester, which will be studied for their biodegradation behaviour. Synthetic analogues of material‐origin PHB can be prepared by ring‐opening polymerization of β‐BL using various organometallic catalysts 4–12. Ring‐opening polymerization of the β‐BL ring for the preparation of poly(( R,S )‐β‐hydroxybutyrate) allows modulation of the polymer chain stereochemistry, which is not possible through the biosynthetic route where only R stereochemistry has been observed.…”

Syndiospecific ring-opening polymerization of .beta.-butyrolactone to form predominantly syndiotactic poly(.beta.-hydroxybutyrate) using tin(IV) catalysts

“…An excellent example of such work is that which has been carried out for the preparation of the poly(¡3-hydroxybutyrate) (PHB) from butyrolactone (BL) using various organometallic species to catalyze the ring-opening polymerization. [1][2][3][4][5][6][7][8][9] The corresponding natural polymer (fi)-PHB is a member of a family of poly(jS-hydroxyalkanoates) (PHAs) that are formed by a wide variety of bacteria.10 An important consideration for the purposes of this paper is that the natural polymer has to date been found exclusively in the enantiomerically pure form where the stereocenters are in the (fi) configuration. Clearly, an important advantage associated with the ring-opening route to PHB and other PHAs is the possibility of preparing these polymers in a variety of stereochemical forms having tailored physical and biological characteristics.…”

Ring‐opening polymerization of cyclic esters promoted by phosphido‐diphosphine pincer group 3 complexes

“…Synthetic analogues of natural‐origin PHB can be prepared by the ring‐opening polymerization of β‐butyrolactone (BL) using various organometallic catalysts 39, 61–67. Few examples of Group 3 metal complexes as was efficient initiators for the ROP of β‐butyrolactone have been recently reported 29, 68–70…”