Would any of you have an idea whether one of the following alpha-esters of lactic acid could be further reacted to the 'ester of hydrobromic acid'
__> 2-bromopropanoic acid ? The nitric acid ester looks interesting.
J.Gen.Chem.USSR 30,1.1960 - 191-1925g of zinc lactate was added in small portions, with stirring, to a mixture of 4.6 ml of HNO3 (d 1.5) and 5.5ml of H2SO4 (d 1.84) stirring was continiued for one hour more, the the mixture was poured onto ice, extracted with ether, and the ether solution was washed with water and dried over Na2SO4. After evaporation of the ether, the residue was distilled in vacuo. The yield was 2.3g (52.5%)
Patent US2399595
preparation of alpha acetoxy propionic acid from lactic acid A mixture consisting of 112g of 80% lactic acid (containing 1 mole of available lactic acid), 1000g of glacial acetic acid, 200ml of benzene, and 1ml of concentrated sulfuric acid, was refluxed for 8 hours with continuous removal of water. After neutralization with sodium acetate, a 78% yield of acetoxypropionic acid was obtained on distillation.
Patent US2465892
preparation of alpha acetoxy propionic acid from sodium lactateA mixture of 30.6 parts of sodium lactate, 80 parts by volume of glacial acetic acid and 80 parts by volume of xylene are heated at the boil under atmospheric pressure in a vessel fitted with a condenser having a device, for example, a Dean and Stark moisture determination apparatus, to enable the aquaeous layer of the condensate to be removed and the xylene layer to be returned to the reaction vessel. The heating is continued until no more water can be collected. The mixture remaining in the reaction vessel is then distilled under a pressure of about 100 mm in order to remove the xylene and unchanged acetic acid. The residue contains 41,5 parts of sodium alpha-acetoxy-propionate which represents a yield of 98,5%. The product can be purified by crystallisation from acetic acid.
The free alpha-acetoxy-propionic acid my be obtained as follows: A mixture of 13.7 parts of concentrated sulfuric acid of 98% strength and 20 parts by volume of glacial acetic acid is added very slowly to the above residue containing 41,5 parts of sodium alpha-acetoxy-propionate, and care is taken to maintain the mixture at about 15°C. The resulting mixture is allowed to stand for 24 hours in order ro enable the precipitated sodium sulphate to remove the water present. The mixture is then filtered to remove the sodium sulphate, and the filtrate is fractionally distilled under reduced pressure to recover 30.3 parts of alpha-acetoxy-propionic acid.
Patent US2518456
preparation of alpha-acetoxypropanoic acid and methyl alpha-acetoxypropionate from methyl lactate;
preparation of ethyl alpha-formoxypropionate and ethyl alpha-acetoxypropionate from ethyl lactate One mole of methyl lactate, 6 moles of acetic acid, 200 ml of benzene (as the entraining agent) and 0.5 ml of concentrated sulfuric acid (as the catalyst) were placed in a one liter, round-bottom flask, fitted with a thermometer through a 10mm internal diameter side arm. The flask was attached to a 24-inch Vigreuax column (approximately 20 inches indented) well wrapped with asbestos insulation. The top of the column was fitted with a modified Barrett moisture trap (either plain or water cooled) above which was placed a condenser. Refluxing was carried out at 91-93°C (temperature of reaction mixture) for approximately five hours until about 18 to 20 ml of water formed during the reaction and removed with the entraining agent was collected as a layer in the trap. The flask was then transferred to another Vigreaux column fitted with a still-head. The thermometer in the flask was replaced by a capillary tube for use during the vacuum distillation. Benzene and excess acetic acid were removed under vacuum supplied by a simple water pump. Methyl alpha-acetoxypropionate in a yield of 0.35 mole and alpha-acetoxypropionic acid in a yield of 0.51 mole were recovered by distillation at higher vacuum using a motor-driven pump.
The above-described experiment was repeated on a larger scale using toluene as the entraining agent, and the distillate was collected and examined. The distillate was found to contain the entraining agent, water, and methyl acetate, the latter being obtained in high yield.
Variations in the procedure of Example I may be made. Toluene, isopropyl acetate, ethylene chloride, methylene chloride, Skelly solve "B" (essentially n-hexane, boiling range 63 - 70°C), cyclohexane, or other entraining agents my be substituted for benzene, some of which will result in a somewhat higher yield of the formed acid and lower yield of the formed ester. Also, the excess of reacting acid my be varied over a wide range without appreciable effects.Variation in the amount of catalyst used does, however, significantly affect the yields, the larger quantity of catalyst tending to increase the yield of the formed acid and decrease the yield of the formed ester. Example I, starting with 1 mole methyl lactate, repeated with 0.7ml sulfuric acid gave 0.2 mole of the ester and 0.68 mole of the acid.
Although this invention is primarily concerned with the production of alpha-acetoxypropionic acid and the auxiliary ester, methyl alpha-acetoxypropionate, other acyloxy carboxylic acids and auxiliary esters may be produced by following the procedure of Example I, except for substituting other reacting esters and other reacting carboxylic acids, and of course, adjusting , adjusting the distillation temperatures properly to recover the formed products.
ethyl lactate + acetic acid
__> alpha-acetoxypropionic acid (0.5mol, bp:75-79°C/0.1mm) + ethyl alpha-acetoxypropionate (0.88 mol, bp:91°C/28mm)
ethyl lactate + formic acid
__> ethyl alpha-formoxypropionate (0.88 mol, bp:?)
Although the above examples disclose sulfuric acid as the catalyst, other acids, such as sulfonic acid may be used. Also, the reactants may be dissolved in a mutual solvent, if desired.
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psyloxy--
