R-3-hydroxybutyrate

DIRECT DEGRADATION OF THE BIOPOLYMER POLY[(R)-3-HYDROXYBUTYRIC ACID] TO (R)-3-HYDROXYBUTANOIC ACID AND ITS... 

A, (R)-(-)-Methyl 3-hydroxybutanoate. A 2-L, round-bottomed flask is charged with 50 g (0.58 mol) of poly-[(R)-3-hydroxybutyric acid] (PHB) (Note 1) and 500 mL of absolute 1,2-dichloroethane. The flask is equipped with a reflux condenser, and the mixture is heated at reflux lor 1 hr. A solution of 10 mL of coned sulfuric acid in 200 mL of absolute methanol is added and the reaction mixture is heated at reflux for 3 days. During this time the mixture becomes homogeneous. 

The submitters used PHB=Poly-(R)-3-hydroxybutyric acid obtained from Marlborough Biopolymers Ltd., Rudby Hall, Hutton Rudby, Yarm, Cleveland, England, PHB homopolymer, BX G04, technical grade powder, MBL 100/703. The checkers used PHB from Fluka Chemie AG, CH-8470 Buchs, Switzerland. The submitters report that the procedure works well on batch sizes of 200-250 g. 

Dioxanone derivatives.1 The optically active 1,3-dioxanone (acetal lactone) 1 is obtained by reaction of (R)-3-hydroxybutyric acid with pivalaldehyde in the presence of an add catalyst. These derivatives can be used to effect enantio-selective reactions at the 2-, 3-, and 4-positions of (R)-3-hydroxybutyric acid. Thus,... 

A preliminary report has identified pheromone blends for two tropical species, Distantiella theobroma and Suhlbergella singularis [146]. Females of both species produce hexyl (R)-3-hydroxybutyrate and its ( )-2-butenoate ester (-1 2). In initial field trials, male S. singularis were attracted to the blend. Further work is in progress to conclusively identify and optimize blends for each species [146]. 

Research Focus Synthesis of amphiphilic terpolymers containing ethylene oxide and (R)-3-hydroxybutyrate and hydrogels containing cyclodextrin. Originality Ongoing 3-year investigation. 

Observations Poly[(R)-3-hydroxybutyrate] is an optically active biodegradable polyester... 

A reactor was charged with poly[(R)-3-hydroxybutyrate], diethylene glycol, dibutyltin dilaurate, and diglyme and then heated overnight and the telechelic hydroxylated prepolymer isolated and used without further purification. 

Preparation of poly ethylene oxide-6-[(R)-3-hydroxybutyrate diol-fr-ethylene oxide ... 

TABLE 1. Physical Properties of Polyfethylene oxide-6-[(R)-3-hydroxybutyrate] diol-h-ethylene oxide Prepared by Transesterification of [(R)-3-hydroxybutyrate] with Methoxy Polyethylene Glycol... 

Critical micelle concentration in aqueous solutions was determined by fluorescence using pyrene as a probe. The driving force for micelle formation is the strong hydro-phobic interactions between [(R)-3-hydroxybutyrate] block. It was previously determined by this group that terpolymers with longer PHB blocks have much lower critical micelle concentrations because of PHB block aggregation in aqueous solution. Testing results are provided in Table 2. 

Poly-[(R)-3-hydroxybutyric acid], PHB Butyric acid, 3-hydroxy-, D-(-)-, polyesters (8) Butanoic acid, 3-hydroxy-, (R)-, homopolymer (9) (29435-48-1)... 

Incidentally, the raw material for the six-membered ring of Trusopt is (R)-3-hydroxybutyrate, which in turn is obtained from biologically derived poly-(R)-3-hydroxybutyrate. 

The copolymer poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-PHV) produced by A eutrophus has generated more interest than poly-(R)-3-hydroxybutyrate (PHB) homopolymer. Since these bacterial polyesters are biodegradable thermoplastics, their mechanical and physical properties have received much attention. PHB is a relatively stiff and brittle material because of its high crystallinity. However, the physiochemi-cal and mechanical properties of [P(HB-HV)] vary widely and depend on the molar percentage of 3-hydroxyvalerate (HV) in the copolymer (4,5) as shown inTable 1. Propionic acid is converted by a synthetase to propionyl-CoA, and the biosynthetic P-ketothiolase catalyzes the condensation of propionyl-CoA with acetyl-CoA to 3-ketovaleryl-CoA by the acetoacetyl-CoA reductase. The hydroxyvaleryl moiety is finally covalently linked to the polyester by the PHA synthase (6). 

R. N. Reusch (1999b). Streptomyces lividans potassium channel contains poly-(R)-3-hydroxybutyrate and inorganic polyphosphate. Biochemistry, 38, 15666-15672. 

R. N. Reusch, O. Shabalin, A. Crumbaugh, R. Wagner, O. Schroder and R. Wurm (2002). Post-translational modification of E. coli histone-like protein H-NS and bovine histones by short-chain poly-(R)-3-hydroxybutyrate (cPHB). FEBS Lett., 527, 319-322. 

D. Seebach, M. Burger, H. M. Muller, U. D. Lengweiler, A. K. Beck, K. E. Sykes, P. A. Barker, and P. J. Barham (1994b). Synthesis of linear oligomers of (R)-3-hydroxybutyrate and solid-state structural investigations by electron microscopy and X-ray scattering. Helv. Chim. Acta, 77, 1099-1123. 

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