Isopropyl lactate

When either of the reactants is sensitive to mineral acids, the esterification can often be successfully accomplished with the aid of a cation exchange resin (hydrogen form) in the presence of benzene. Zeo-Karb 225/H, a unifunctional sulphonated polystyrene resin in the hydrogen form, may be used. Thus good yields of isopropyl lactate may be obtained ... 

Furfuryl acetate. Reflux a mixture of 39 2 g. (34 8 ml.) of redistilled furfuryl alcohol, 48 g. of glacial acetic acid, 150 ml. of benzene and 20 g. of Zeo-Karb 225/H in a 500 ml. bolt-head flask, using the apparatus described under isoPropyl Lactate. After 3 hours, when the rate of collection of water in the water separator is extremely slow, allow to cool, separate the resin by suction filtration, and wash it with three 15 ml. portions of benzene. Remove the benzene, etc., from the combined filtrate and washings under reduced pressure (water pump) and then collect the crude ester at 74-90°/10 mm. a small sohd residue remains in the flask. Redistil the crude ester from a Claisen flask with fractionating side arm pure furfuryl acetate passes over at 79-80717 mm. The yield is 14-5 g. 

A = 10781 C6H12O3 C6H12O3 2-Ethoxyethyl Acetate Isopropyl lactate 156.8 166.8 Nonazeotrope 256... 

A = 10833 c6h12o3 C6H140 Isopropyl Lactate Hexyl alcohol 166.8 157.85 Nonazeotrope 255... 

A - 10841 C6H12O3 CioHia Isopropyl Lactate (continued) a-Pinene 166.8 155.8 152.5 22 255... 

Notes. (1) The purified commercial dibutyl (+ )-tartrate, m.p. 22 °C, may be used. It may be prepared by using the procedure described under isopropyl lactate (Expt 5.145). Place a mixture of 75g of (-I-)-tartaric acid, lOg of Zerolit 225/H , 110g (135 ml) of redistilled butan-l-ol and 150 ml of sodium-dried benzene in a 1-litre threenecked flask equipped with a sealed stirrer, a double surface condenser and an automatic water separator (cf. Fig. 2.31(a)). Reflux the mixture w th stirring for 10 hours about 21 ml of water collects in the water separator. Filter ol the ion-exchange resin... 

Cognate preparations. Butyl oleate. Proceed as for isopropyl lactate using 28 g (0.1 mol) of redistilled oleic acid, 37.0 g (46 ml, 0.5 mol) of butan-l-ol (the excess of the latter acts as the water carrier) and 8.0 g of Zerolit 225/H in a 250-ml flask. Reflux the mixture with magnetic stirring for 4 hours, allow to cool, separate the resin by suction filtration and wash it with three 5 ml portions of butan-l-ol. Remove the butanol from the combined filtrate and washings by distillation under reduced pressure (water pump) the residue consists of crude ester. Distil the residue under diminished pressure (oil pump) and collect the butyl oleate at 232 °C/9 mmHg. The yield is 27 g (85%). 

While the reactions ofketenes with enantiopure alcohols usually give modest selectivities [769], the use of (ethyl lactate (proton donors has allowed the highly enantioselective formation of 2-arylpropionic esters. A mild hydrolysis (AcOH/HCl or LiOH) leads to the corresponding adds, which are anti-inflammatory drugs [554,923] (Figure 4.8). This method has been extended by Durst and Koh [861, 999] to the synthesis of enantioenriched a-halogenated esters, which are precursors of aminoacids (Figure 4.8). 

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