L -Lactic acid

C, b.p. 150 C/25mm. Prepared from l-lactic acid. It is partially converted to lactic acid by water. o-Lactide is similar. DL-Lactide crystallizes in colourless needles, m.p. 124-5 "C, b.p. l42°C/8mm. Obtained from DL-lactic acid. 

Lactic acid is also the simplest hydroxy acid that is optically active. L (+)-Lactic acid [79-33-4] (1) occurs naturally ia blood and ia many fermentation products (7). The chemically produced lactic acid is a racemic mixture and some fermentations also produce the racemic mixture or an enantiomeric excess of D (—)-lactic acid [10326-41-7] (2) (8). 

Polylactide is the generaUy accepted term for highly polymeric poly(lactic acid)s. Such polymers are usuaUy produced by polymerization of dilactide the polymerization of lactic acid as such does not produce high molecular weight polymers. The polymers produced from the enantiomeric lactides are highly crystalline, whereas those from the meso lactide are generaUy amorphous. UsuaUy dilactide from L-lactic acid is preferred as a polymerization feedstock because of the avaUabUity of L-lactic acid by fermentation and for the desirable properties of the polymers for various appUcations (1,25). 

Braided Synthetic Absorbable Sutures. Suture manufacturers have searched for many years to find a synthetic alternative to surgical gut. The first successful attempt to make a synthetic absorbable suture was the invention of polylactic acid [26023-30-3] suture (15). The polymer was made by the ring-opening polymerization of L-lactide [95-96-5] (1), the cycUc dimer of L-lactic acid. 

Enzyme-catalyzed reductions of carbonyl groups are, more often than not, completely stereoselective. Pyruvic acid, for example, is converted exclusively to (.S)-(-l-)-lactic acid by the lactate dehydrogenase-NADH systeim (Section 15.11). The enantioimer... 

The enzyime is a single enantioimer of a chual imolecule and binds the coenzyime and substrate in such a way that hydride is transfened exclusively to the face of the cabonyl group that leads to (5)-(-l-)-lactic acid. Reduction of pyruvic acid in the absence of an enzyime however, say with sodium borohydride, also gives lactic acid but as a racemic mixture containing equal quantities of the R and S enantiomers. 

Figure 9.8 Assignment of configuration to (a) (R)-l-l-lactic acid and (b) (S)-(-i-)-lactic acid.

Poly(L-lactic acid) EcoPLA, NatureWorks Dow-Cargill Environmental, biomedical Lactic acid from corn starch fermentation... 

Poly(L-lactic acid) Lacty Shimadzu Environmental, biomedical b... 

Oligomerization Two hundred grams of a 90% aqueous solution of L-lactic acid is charged into the flask and is dehydrated at 150°C, first at atmospheric pressure for 2 h, then at a reduced pressure (130 mbar) for 2 h, and finally under a pressure of 40 mbar for another 4 h. A viscous oligo(L-lactic acid) is formed quantitatively. 

PLA degradation, 43 Planar polymer, synthesis of, 505 PLLA. See Poly(L-lactic acid) (PLLA) PMDA. See Pyromellitic dianhydride (PMDA)... 

Polylactides, 18 Poly lactones, 18, 43 Poly(L-lactic acid) (PLLA), 22, 41, 42 preparation of, 99-100 Polymer age, 1 Polymer architecture, 6-9 Polymer chains, nonmesogenic units in, 52 Polymer Chemistry (Stevens), 5 Polymeric chiral catalysts, 473-474 Polymeric materials, history of, 1-2 Polymeric MDI (PMDI), 201, 210, 238 Polymerizations. See also Copolymerization Depolymerization Polyesterification Polymers Prepolymerization Repolymerization Ring-opening polymerization Solid-state polymerization Solution polymerization Solvent-free polymerization Step-grown polymerization processes Vapor-phase deposition polymerization acid chloride, 155-157 ADMET, 4, 10, 431-461 anionic, 149, 174, 177-178 batch, 167 bulk, 166, 331 chain-growth, 4 continuous, 167, 548 coupling, 467 Friedel-Crafts, 332-334 Hoechst, 548 hydrolytic, 150-153 influence of water content on, 151-152, 154... 

Broz, M.E., VanderHart, D.L. and Washburn, N.R. 2003. Structure and mechanical properties of poly(d,l-lactic acid)/poly(e-caprolactone) blends. Biomaterials 24 4181-4190. 

Tsuge, T., Shimoda, M, Ishizaki, A., 1999. Optimization of L-Lactic acid feeding for the... 

POLYd, 3-TRIMETHYLENE CARBONATE) AND THEIR COPOLYMERS WITH d,l-LACTIC acid ANDE-CAPROLACTONE... 

The earliest reports of controlled release steroids were those of Jackanicz (63), Yolles (64), Anderson (65), and Wise (66). Most of those early studies were based on poly[ (L+)-lactic acid). Implants and granular particles were fabricated with progesterone, norgestrel, and norethisterone. In vivo urinary excretion studies were conducted on [I Cjprogesterone beads (64). The reported results were somewhat questionable as only 20% of the original implanted drug could be accounted for. 

Various antimalarial drugs have been studied in biodegradable delivery systems. Wise (89) reported the use of a lactide/glycolide copolymer and also poly(L-lactic acid) for release of drugs such as quinazoline and sulfadiazine. Although in vitro data and experiments in mice were somewhat encouraging, these early formulations failed to reach significant clinical status. 

Christei, P., Chabot, F., and Vert, M., In vivo fate of bioresorbable bone plates of long-lasting poly(L-lactic acid), Proc. 2nd World Congress on Biomaterial, 279, 1984. 

Low molecular weight. For poly(L-lactic acid) of high molecular weight [MW = 500,000], the tensile strength is about 500 kg/cm and the tensile modulus is about 25,000 kg/cm. ... 

Bicontinuous Controlled-Release Matrices Composed of Poly(D,L-lactic acid) Blended with Ethylene—Vinyl Acetate Copolymer... 

Barry, J. J., Ph.D Thesis, Evaluation and Characterization of the Degradation and Silver Release From a Poly (d,l- Lactic Acid) - Silver Matrix, Department of Chemistry, University of Lowell, 1988, Bl-1,92. 

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