Lactic acid crystallization

Some authors use m/m instead of m/v, which changes the actual concentration of the active ingredients. It is also important to stress the need for the pharmacist to use the crystal form of the lactic acid and not the solution form. Lactic acid in fact comes in liquid form with a concentration of 85%. The pharmacist should use lactic acid crystals and not solution to prepare the Jessner solution. Moreover, different molecules, many of them unknown, are used to denature alcohol, to make it unfit for drinking, and there is a risk of potential chemical interactions with the acids. The alcohol used by the pharmacist must be pure, not denatured. Resorcinol solutions have been used at concentrations of 10-50% in alcohol or ether to treat keratoses. 

Narita, 1., Katagiri, M. and Tsuji, H. (2011) Highly enhanced nucleating effect of melt-recrystaUized stereocomplex crystallites on poly(L-lactic acid) crystallization. Macromolecular Materials and Engineering, 296, 887-893. 

Fujita, M., Sawayanagi, T., Abe, H., Tanaka, T., Iwata, T., Ito, K. et al. (2008) Stereocomplex formation through reorganization of poly(L-lactic acid) and poly(D-lactic acid) crystals. Macromolecules, 41, 2852-2858. 

In principle, the known techniques can be employed for crystallization of LA. An example of such a technique is melt crystallization (cooling crystallization), which involves direct cooling of the condensed, liquid concentrate or distillate containing (s)- or (r)-lactic acid in the molten state, so that the (5)- or (r)-lactic acid crystallizes out. It is preferable to keep the temperature at which crystallization occurs (the crystallization temperature) as low as possible, so that the formation of oligomers and poljmers of lactic acid is limited as less as possible. 

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. 

In the reaction of lactic acid to form pyruvic acid over the iron phosphate catalysts, formation of a new compound was observed. As the extent of reaction increased, the amount of pyruvic acid increased to a maximum and then decreased, while that of the new compound increased steadily. It was therefore concluded that the new compound is formed from pyruvic acid in parallel with acetic acid and CO2. According to gas-mass analyses, the molecular weight was determined as 112. However, there are many compounds with molecular weigth of 112. After the NMR analyses and X-ray diffraction analyses for the single crystal, the new compound was determined to be citraconic anhydride, i.e., mono-methyl maleic anhydride. 

Pharmacoiogy The exact mechanism of action of colchicine in gout is not known. Colchicine apparently exerts its effect by reducing the inflammatory response to the deposited crystals and also by diminishing phagocytosis. Colchicine diminishes lactic acid production by leukocytes directly and by diminishing phagocytosis and thereby interrupts the cycle of urate crystal deposition and inflammatory response that sustains the acute attack. 

Mechanism of Action An alkaloid that decreases leukocyte motility, phagocytosis, and lactic acid production. Therapeutic Effect Decreases urate crystal deposits and reduces inflammatory process. 

The appearance of the individual microcapsules is shown in Fig. 1. Most individual microcapsules are approximately spherical and show a surface made up of deposited plates of poly(DL-lactic acid) in which the drug is embedded. Many of the larger microcapsules are cemented together by further plates of poly(DL-lactic acid). The effect of compression on these microcapsules is shown in Fig. 2. At a compressive force of 2 kN (Fig. 2(a)) the electron micrograph of the tablet fracture surface shows that the microcapsules, while distorted, remain essentially intact and rounded, with a relatively open porous structure to the tablet as a whole. At 10 kN force (Fig. 2(b)) the microcapsules at the fracture are flattened, cracked and distorted so that the fracture surface shows a far less open, porous aspect. Both of these microcap tablets have a very different appearance from that produced by the simple mixture (Fig. 3), where the individual plates of poly(DL-lactic acid) are mixed with the drug crystals in an open structure from which release would be easily... 

Figure 2.12 Effect of added lactic acid (--) and degree of lactose crystallization (-) on the...

Our work (6, 7, 8) has shown that the same protein which causes the malic acid-lactic acid transformation will also cause the production of a small amount of pyruvic acid from malic acid. However, the pyruvic acid produced is not involved with lactic acid production. Apparently, one protein is producing two end products from the same substrate. The malic acid to lactic acid activity is not an oxidoreductase whereas the malic acid to pyruvic acid activity is. Since the pyruvic acid producing activity is only a small per cent (about 0.2%) of the malic acid to lactic acid activity, and since the enzyme should be classified according to the major end product, the enzyme has been given the trivial frame of malo-lactic enzyme (6, 7, 8). Schiitz (28) has speculated that if this enzyme were crystallized, it should be called malate-carboxy-lyase. In either case, use of either the trivial or accepted terms for the malic enzyme is not recommended. 

These researchers found no correlation between hygroscopicity of the powders and degree of lactose crystallization, but there was a direct correlation between hygroscopicity and the amount of lactic acid in the powder. Acid whey permeate dried readily, however, without many of the problems encountered during the drying of whole whey. 

Azomethine derived ferroelectric liquid crystals As DOBAMBC, many ferroelectric LC s were prepared utilizing amyl alcohol as the chiral source. The reason for the small spontaneous polarization of DOBAMBC is the separation between the C=0 dipole moment and the chiral carbon. This effect can be explained by the intramolecular rotation or vibration of the carbonyl dipole moment relative to the chiral carbon, because they are not adjacent. There are some rules linking the molecular structure and the direction of the spontaneous polarization (minus or plus). In order to reduce the separation between the carbonyl dipole moment and the chiral carbon, ferroelectric LC s were synthesized utilizing a secondary alcohol as the chiral source. Ferroelectric LC s with large spontaneous polarizations have large dipole moments at the chiral centre. Ferroelectric LC s with halogen or nitrile units connected directly to the chiral carbon were synthesized from chiral lactic acids or amino acids. 

Reduction of achiral precursors is often used to produce chiral products. The advantage of this approach is that the theoretical yield of product is 100% compared to the 50% theoretical maximum for the resolution of racemates. Cross-linked crystals of lactate dehydrogenase have been used to prepare L-lactic acid from pyruvic acid in an electrolytic cell. The LDH CLCs maintained constant... 

The physical properties and melt processing of PLA are similar to those of conventional packaging resins. It may thus be used as a commodity resin for general packaging application. In many aspects the basic properties of PLA lie between those of crystal PS and PET [ 14]. When plasticized by its own monomer lactic acid, PLA becomes increasingly flexible so that products that mimic PVC, LDPE, LLDPE, PP, and PS can be prepared [15]. Possible applications are espe-... 

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