3-Hydroxy-n-alkanoate

Mcl-PHAs are also classified according to the type of substituent in the alkyl in the side chains so that poly(HAMCL)s containing unsubstituted n-alkyl groups are identified as medium-chain-length poly(3-hydroxy-n-alkanoate) [poly (nHAMCL)]. Both poly(nHAMCL) and PHAs containing unusual groups are described in Sect. 3. 

In this section, poly(HAMCL)s are largely subdivided into two types based on the structures of side groups these are PHAs containing only 3-hydroxy-n-alkanoates and PHAs containing substituted 3-hydroxy-n-alkanoates. 

Medium-Chain-Length-PHAs Containing only 3-Hydroxy-n-alkanoates [poly(nHAMCL)s]... 

A solution of 1 mmol of the 4,5-dihydro-2-(2-hydroxyalkyl)-4.4-dimethyloxazole (4) in 8 mL of 3 N sulfuric acid and is stirred at 80 °C. for 1.5 h. The mixture is cooled to 20 °C and extracted with five 10-mL portions of Et20. The combined organic phase is dried with Na2S04 and concentrated in vacuo to give the 3-hydroxy-alkanoic acid in quantitative yield and in good purity. The known acids are identified by a comparison of physical and spectral data with those of authentic samples. 

U. D. Lengweiler, Biopolymers and -oligomers of (J )-3-Hydroxyalkanoic Acids - Contributions of Synthetic Organic Chemists , Ernst Schering Research Foundation, 1995, 28, 7 - 98 D. Seebach, M. G. Fritz, Detection, synthesis, structure, and function of oligo(3-hydroxy-alkanoates) contributions by synthetic organic chemists , Int. J. Biol. Macromol. 1999, 25, 217 - 236 R. N. Reusch, Transmembrane Ion Transport by Polyphosphate/Poly-(J )-3-hydroxybutyrate Complexes , Biochemistry (Moscow) 2000, 65, 280 - 295 S. Das, D. Seebach, R. N. Reusch, Biochemistry 2002,41,5307-5312. 

Halogenated PHAs. Several halogenated PHAs were obtained when certain bacterial species (P. oleovorans, P. putida) were cultured in media containing chlorinated, brominated or fluorinated compounds. A copolyester containing (R)-3-hydroxyoctanoate, (P)-3-hydroxy-8-chlorooctanoate, (P)-3-hydroxyhexanoate and (/ )-3-hydroxy-6-chlorohexanoate was synthesized when a culture of P. oleovorans was fed with octane and 1-chlorooctane as carbon sources (Doi and Abe 1990). Additionally, PHAs containing brominated monomers were produced by P. oleovorans when it was cultured in media containing mixtures of n-alkanoic acids (octanoic and nonanoic acids) and co-bromoalkanoic acids (Kim et al. 1992). 

Hervas AB, Canosa I, Santero E (2008) Transcriptome analysis of Pseudomonas putida in response to nitrogen availability. J Bacteriol 190 416-420 Hoffmann N, Rehm BH A (2004) Regulation of polyhydroxyalkanoate biosynthesis in Pseudomonas putida and Pseudomonas aeruginosa. FEMS Microbiol Lett 237 1-7 Hori K, Soga K, Doi Y (1994) Production of poly(3-hydroxyaIkanoates-co-3-hydroxy->v-fluoro-alkanoates) by Pseudomonas oleovorans from 1-fluorononane and gluconate. Biotechnol Lett 16 501-506... 

Huijberts, G. N. M., de Rijk, T. C., de Ward, R, Eggink, G. C nuclear magnetic resonance study of Pseudomonas putida fatty acid metabohc routes involved in poly(3-hydroxy-alkanoate) synthesis. J Bacterial 1995,176,1661-1666. 

The aliphatic-aromatic diacid monomers were prepared from the reaction of bromoalkanoic acid methyl ester and p-hydroxy benzoic acid methyl ester. The polymers of carboxyphenoxy alkanoic add of n = 3, 5, and 7 methylenes were soluble in chlorinated hydrocarbons and melted at temperatures below 100 °C. Copolymers of these monomers melted at lower temperatures than the respective homopolymers. These polymers displayed zero-order hydrolytic degradation profile ranging from 2 to 10 weeks. Increasing the length of the alkanoic chain, decreased the degradation rate of the polymer (Fig. 3). 

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