Lactic 2,3-diphenyl

A solution of Grignard reactive (prepared from 247 g of o-bromoanisole and 31.6 g of magnesium in 1500 ml of ether) is added dropwise to a solution of 91 g of diphenyl pyruvic acid in ether. The mixture is refluxed for 2 hours. After cooling to the reaction mixture is added 5% hydrochloric acid and the product is extracted with 5% solution of sodium hydroxide. a-(o-Anisyl)-p,15-diphenyl lactic acid is precipitated by addition of concentrated hydrochloric acid yield 62 g, melting point 194-195°C. 

Azeotropic dehydration and condensation polymerization (route 2 in Figure 8.2) yields directly high molar mass polymers. The procedure, patented by Mitsui Toatsu Chemicals [13, 14], consists of the removal of condensation water via a reduced pressure distillation of lactic acid for 2-3h at 130°C. The catalyst (in high amounts) and diphenyl ester are added and the mixture is heated up to reflux for 30-40 h at 103°C. Polycondensated PLA is purified to reduce residual catalyst content to the ppm range [5,10,15]. 

Diphenyl-lactic Acid (2 2-Diphenyl-l-hydroxypropwiiic acid bemhydrylglycollic acid)... 

Diphenyl-lactic Acid (PhenyWepzyU glycoilic add, 1 2-diphenyl l-hydroxypropionie a id)... 

Urethane diacrylate + poly(L-lactic acid) Dioxane Diphenyl-(2,4,6-methyl- -25 Preparation of macroporous [172]... 

In 1995, as mentioned above, Ajioka et al. first succeeded in synthesizing PLLA having higher than 100 kDa by using diphenyl ether as an azeotropic solvent.In this polycondensation system the high boiling solvent was refluxed at reduced pressure to azeotropically distil the condensed water and to make it adsorb on molecular sieves. This method is especially effective for the co-polycondensation of L-lactic acid with other monomers (hydrojgrl-acids and diol/dicarbojq lic acid combinations). 

Better polymerisation of lactic acid with tin salts as catalysts can be carried out in multiple steps. Lactic acid is heated at 150 °C with tin catalyst to obtain oligomeric PLA (with a degree of polymerisation of 1-8). The oligomers are then heated at 180 °C imder vacuum (1333 Pa) for 5 hours to give PLA of high MW (100,000). Finally the third step is carried out at solid state above the crystallisation temperature, T,., (105 °C, 66 Pa, 0.5-2 hours) and annealing 150 °C for 10-30 hours. A PLA of MWup to 600,000 is obtained. Solution polymerisation in diphenyl ether results in a PLA of MW of 140,000. 

A reverse ATRP system was investigated with the free radical initiator/SmCls/lactic add system (Ln-4) to mediate the controlled polymerizations of MMA and methacrylonitrile (MAN). The MMA polymerization with AIBN/SmQ3/lactic add at 80 ° C produced wdl-controUed polymers bearing narrow MWDs (Mw/Mn 1.3) with the Mn inaeasing in direct proportion to the conversion up to 20 000, in which the catalysis was proposed to take place with an equilibrium between the Sm(II) and Sm(III) spedes. The MAN polymerization was conducted by SmQ3 and lactic add in DMF with diethyl 2,3-dicyano-2,3-diphenyl succinate as the thermal initiator to produce a fairly narrow MWD poly (MAN) (MjMn=l.l-1.2). ... 

Suitable mechanisms have been proposed following determination of the kinetic and activation parameters for oxidation of 2-naphthol and cyclic ketones by nicotinium dichromate some a-amino acids by tripropylammonium fluorochromate " distyryl ketone by quinaldinium fluorochromate methanol by benzyltriethylammonium chlorochromate catalysed by 1,10-phenanthroline substituted benzyl alcohols by tetraethylammonium bromochromate L-cysteine by pyridinium bromochromate lactic acid and 3,5-dimethyl-2,6-diaryl piperidin-4-one oximes by pyridinium chlorochromate allyl alcohol by IDC benzophenoxime by bispyridine silver(I) dichromate and alkyl phenyl sulfides by cetyltrimethylammonium dichromate. A non-linear Hammett plot obtained for the oxidation of substituted benzyl alcohols by IDC has been attributed to the operation of substituent effect on two steps of the proposed mechanism. " Kinetic and activation parameters for oxidation of o-toluidine and of A-methyl-2,6-diphenyl piperidin-4-one oxime and its 3-alkyl derivatives by sodium dichromate have been determined and suitable mechanisms have been suggested. Micellar catalysis in the 1,10-phenanthroline-promoted chromic acid oxidation of propanol... 

DPPA has been used for the direct C-acylation of methyl isocyanoacetate with carboxylic acids to give 4-methoxycarbonyloxazoles. t-Daunosamine, the glycone component of anticancer anthracycline antibiotics, has been synthesized from L-lactic acid in 9 steps with a 24% overall yield, where a key step in the sequence is the direct C-acylation of methyl isocyanoacetate with the lithium salt of the lactate ester using diphenyl phosphorazidate (eq 7). 

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