anwering own question - it looks OK...
lactic acid or salt, + MeOH (or EtOH) --> simple esterification (H2SO4) --> alkyl lactate.
- the carboxyllic alcohol is the most reactive towards alcohols. elimination of water is a difficulty also purification. if the details could be hammered out, then it looks like a good route to alkyl2-halopropionate.
Then chlorination -
(a)methyl lactate with thionyl chloride --> methyl2-chloropropionate
Post 462801
(Rhodium: "Methyl 2-Chloropropionate from Methyl Lactate", Novel Discourse)(b) or toluenesulfonyl chloride --> alkyl 2-chloropropionate.
LACTIC ESTERS Preparation and Properties
Lee T. Smith, H. V. Claborn;
Ind. Eng. Chem.; 1940; 32(5); 692-694.Lactic acid possesses two active hydroxyl groups; therefore, three types of esters are possible -
(a) the hydroxyl in the carboxyl group will react with an alcohol to form the corresponding lactic acid ester, ch2chohcooR
(b) the secondary alcohol group in the alpha position of these esters reacts with acid chlorides, acid anydrides and ketene to form the corresponding alpha oxy-propionate
(c) similarly the secondary alcohol group in lactic acid reacts with acetic anhydride and acid chlorides to form the alpha oxyproponic acid.
The esterification of the hydroxyl in the carboxyl group is easily accomplished by the reaction of an alcohol with lactic acid, especially if a small amount of sulfuric acid is used as catalyst. The yield of the ester will vary from about 60 to nearly 100 percent, depending largely upon the method used for removing the water as it is formed during the esterification reaction. It is more difficult to obtain a high yield of ester with methyl or isopropyl alcohol than it is with a long chain alcohol such as butyl, amyl cetyl
because the lower alcohols and the corresponding lactic esters are soluble in water and do not form azeotropic mixtures with benzene, toluene, ethyl acetate etc. It is necessary, therefore to resort to other methods of removing this water or reducing the ratio of water to alcohol in the reacting mixture by using a large excess of alcohol. The general methods used in the preparation of the esters are given in the following sections.
Low-Boiling esters soluble in water
Five moles calcium lactate or 10 moles sodium lactate, dry basis, are dissolved or mixed with 50 moles methanol, ethanol or ispropanol. An equivalent amount of sulfuric acid is added to liberate the lactic acid and precipitate the calcium or sodium sulfate. An additional 20 grams of sulfuric acid is also added as catalyst. The mole ratio of this mixture … This mixture is heated for 4 to 8 hours at refluxing temperature to complete the esterification.
Then get a complex series of fractional distillation.
Needs to be a simpler manner to do this…
The yield of refined ester based on the lactic acid present at the start will vary from 70 to 90 percent. The variation depends upon the amount of water present in the raw materials, techinique used during the operations, and efficiency of the fractionating columns employed for separating the excess alcohol, water and unchanged lactic acid from the ester.
Properties of Esters
Methyl Bp 144.8 degC at 760mm
Ethyl Bp 154.5 at 760.
