Hydroxyalkanoates

Figure 15.7 Cliromatographic separation of cliiral hydroxy acids from Pseudomonas aeruginosa without (a) and with (h) co-injection of racemic standards. Peak identification is as follows 1, 3-hydroxy decanoic acid, methyl ester 2, 3-hydroxy dodecanoic acid, methyl ester 3, 2-hydroxy dodecanoic acid, methyl ester. Adapted from Journal of High Resolution Chromatography, 18, A. Kaunzinger et al., Stereo differentiation and simultaneous analysis of 2- and 3-hydroxyalkanoic acids from hiomemhranes hy multidimensional gas cliromatog-raphy , pp. 191 -193, 1995, with permission from Wiley-VCH. (continuedp. 419)...

A. Kaunzinger, M. Thomsen, A. Dietiich and A. Mosandl, Stereodifferentiation and simultaneous analysis of 2- and 3-hydroxyalkanoic acids from hiomemhranes by multidimensional gas clnomatography , 7. High Resolut. Chromatogr. 18 191-193 (1995). 

Table 1. Methyl 2-Amino-3-hydroxyalkanoates by Addition of Azaenolatcs from 2.5-Dihydro-3.6-dimeth-oxypyrazines to Saturated Aldehydes and Ketones, Followed by Hydrolysis...

Takagi, Y., Yasuda, R., Yamaoka, M. and Yamane, T. 2004. Morphologies and mechanical properties of polylactide blends with medium chain length poly(3-hydroxyalkanoate) and chemically modified poly(3-hydroxyalkanoate). Journal of Applied Polymer Science 93 2363-2369. 

Formation of Polyesters by Pseudomonas oleovorans Effect of Substrates on Formation and Composition of Poly-(R)-3-Hydroxyalkanoates and Poly-(R)-3-Hydroxyalkenoates. Applied Environmental and Microbiology, 54, 2924-2932. 

Keywords. Bacterial polyester, Medium-chain-length poly(3-hydroxyalkanoates), Pseudomonas oleovorans, Pseudomonas putida, Functional poly(3-hydroxyalkanoates), Short-chain-length poly(3-hydroxyalkanoates)... 

Short-Chain-Length Poly(3-hydroxyalkanoates) [poly(HASCL)s]. . 56... 

Medium-Chain-Length-PHAs Containing Substituted 3-Hydroxyalkanoates... 

Fig. 2A-F. Hydroxy acid monomers of PHAs with varied polymer backbones A standard 3-hydroxyalkanoic acid monomer B 2-methyl-3-hydroxyalkanoic acid monomer C 2,2-di-methyl-3-hydroxyalkanoic acid monomer D 4-hydroxyalkanoic acid monomer E 5-hydroxy-alkanoic acid monomer F 6-hydroxyalkanoic acid monomer. (R indicates alkyl residue or H)...

An alternative to the extraction of intact PHA polymer is the isolation of PHA monomers, oligomers, or various derivatives such as esters [74]. PH As are composed of stereo-chemically pure P-3-hydroxyacids, and therefore can be used as a source of optically pure organic substrates for the chemical and pharmaceutical industry [79]. In this protocol, the defatted cake containing PHA polymer would be chemically treated to obtain the PHA derivatives. For example, transesterification of the meal with methanol would give rise to methyl esters of 3-hydroxyalkanoic acids. The PHA derivatives would then be separated from the meal with appropriate solvents. One potential disadvantage of this method is the potential alteration of the quality of the residual meal if the harsh chemical treatments required for the production of PHA derivatives lead to protein or amino acid breakdown. 

Holmes P (1988) Biologically Produced (R)-3-hydroxyalkanoate Polymers and Copolymers. In Development in Crystalline Polymers, Volume 2. Elsevier, London... 

The diastereoselectivity of the reduction of a-substiluted ketones has been the subject of much investigation. The reagent combination of trifluoroacetic acid and dimethylphenylsilane is an effective method for the synthesis of erythro isomers of 2-amino alcohols, 1,2-diols, and 3-hydroxyalkanoic acid derivatives.86,87,276,375 Quite often the selectivity for formation of the erythro isomer over the threo isomer of a given pair is >99 1. Examples where high erythro preference is found in the products are shown below (Eqs. 218-220).276 Similar but complementary results are obtained with R3SiH/TBAF, where the threo isomer product... 

Carbonylation of epoxides provides direct access to a large variety of hydroxy carbonyl compounds, such as /Mac tones, useful synthons in organic synthesis, and poly(3-hydroxyalkanoate), important biodegradable polyesters. Thus, the development of efficient catalysts for such carbonylations has been widely studied. 

The ring-expansion carbonylation of epoxides is the most widely studied field in the epoxide carbonylation chemistry since the product lactones are highly attractive targets particularly, /1-lactones are useful compounds due to their versatility in organic synthesis [ 14,15] as well as their utilization as monomers to produce poly(3-hydroxyalkanoate)s, naturally occurring biodegradable polyesters [16-19]. 

Poly(3-hydroxyalkanoate)s have potential for application to engineering plastics endowed with biodegradable nature. One of the synthetic approaches to the polyesters is the ring-opening polymerization of -substituted /3-lactones which can be effectively produced by ring-expansion carbonylation of epox-... 

If hydrogen fluoride is used as the catalyst, it is possible to use 3-halogenopropanoic acids in this route (68CB2494), whilst with boron trifluoride even 3-hydroxyalkanoic acids afford chromanones in a very fast reaction (63T77). 

---