Monochloroacetic acid

Transfer the reaction product to a 500 ml. Claisen flask and distil over a wire gauze or from an air bath. Some acetyl chloride and acetic acid passes over first, the temperature then rises, and the fraction, b.p. 150-200°, is collected separately run out the water from the condenser when the temperature reaches 150°. The fraction, b.p. 150-200°, solidifies on cooling. Drain off any liquid from the crystals as rapidly as possible, and redistil the solid using an air condenser. Collect the fraction b.p. 182-192° this sets to a solid mass on cooling and melts at 63°. The yield of monochloroacetic acid is 150-175 g. 

Chloroacetic acid must be handled with great care as it causes blisters on the skin. 

Allow to cool and run in 20 ml. of water slowly to destroy the acetic anhydride. Remove the excess of acetic acid and water by heating on a water bath under reduced pressure (ca. 35mm.). 

The residue (220 g.) crystallises on cooling and consists of almost pure monobromoacetic acid (2). If it is required perfectly pure, distil the crude acid from a Claisen flask and collect the fraction of b.p. 202-204°. When distilled under diminished pressure, the acid boils at 117-118°/15 mm. 

Ethyl bromoacetate (1). Fit a large modified Dean and Stark apparatus provided with a stopcock at the lower end (a convenient size is shown in Fig. Ill, 126, 1) to the 1-litre flask containing the crude bromoacetic acid of the previous preparation and attach a double surface condenser to the upper end. Mix the acid with 155 ml. of absolute ethyl alcohol, 240 ml. of sodium-dried benzene and 1 ml. of concentrated sulphuric acid. Heat the flask on a water bath water, benzene and alcohol will collect in the special apparatus and separate into two layers, the lower layer consisting of approximately 50 per cent, alcohol. Run off the lower layer (ca. 75 ml.), which includes all the water formed in the 

---

This reaction is general for > -chlorocarboxylic acids of these, however onlv monochloroacetic acid is readily and cheaply obtainable, and it also gives the highest yielcf of the nitrohydrocarbon. 

Required Monochloroacetic acid, 50 g. anhydrous sodium carbonate, 30 g. sodium nitrite, 36-5 g. 

A concentrated solution of monochloroacetic acid is neutralised with sodium bicarbonate, and then heated with potassium cyanide, whereby sodium cyano-acetate is obtained ... 

Required Monochloroacetic acid, 30 g. sodium bicarbonate, 30 g. potassium cyanide, 24 g. sulphuric acid, 50 ml. rectified spirit, 70 ml. 

The first part of this preparation (as far as the solidification of the sodium cyanoacetate) must be carried out in the fume-cupboard. Add 30 g. of monochloroacetic acid to 60 ml. of water contained in a wide evaporating-basin (about 12-15 diameter)... 

Nitroethane may be similarly obtained from sodium a chloropropionate. This is a general reaction for a chloro carboxylic acids, but in practice only monochloroacetic acid and a chloropropionic acid are readily available. 

Acetic acid can be chlorinated by gaseous chlorine in the presence of red phosphorus as catalyst to yield successively mono-, di-, and tri-chloroacetic acid the reaction proceeds better in bright sunlight. If the chlorination is stopped when approximately one molecule of chlorine per molecule of acetic acid is absorbed the main product is monochloroacetic acid ... 

Ethyl malonate can be conveniently prepared by neutralising a solution of monochloroacetic acid with sodium bicarbonate, then heating with potassium cyanide to form sodium cyanoacetate ... 

Other acetyl chloride preparations include the reaction of acetic acid and chlorinated ethylenes in the presence of ferric chloride [7705-08-0] (29) a combination of ben2yl chloride [100-44-7] and acetic acid at 85% yield (30) conversion of ethyUdene dichloride, in 91% yield (31) and decomposition of ethyl acetate [141-78-6] by the action of phosgene [75-44-5] producing also ethyl chloride [75-00-3] (32). The expense of raw material and capital cost of plant probably make this last route prohibitive. Chlorination of acetic acid to monochloroacetic acid [79-11-8] also generates acetyl chloride as a by-product (33). Because acetyl chloride is cosdy to recover, it is usually recycled to be converted into monochloroacetic acid. A salvage method in which the mixture of HCl and acetyl chloride is scmbbed with H2SO4 to form acetyl sulfate has been patented (33). 

Fig. 1. The free2ing point of monochloroacetic acid (MCAA)—water mixtures. For wt % acid >75% fp(°C) = 2.17 ...

For many years fluorine has been deterrnined by the Willard-Winters method in which finely ground ore, after removal of organic matter, is distilled with 72% perchloric acid in glass apparatus. The distillate, a dilute solution of fluorosiUcic acid, is made alkaline to release fluoride ion, adjusted with monochloroacetic acid at pH 3.4, and titrated with thorium nitrate, using sodium a1i2arine sulfonate as indicator. 

Devrinol, 2-(l-naphthoxy)-Al,A/-diethylpropionamide/7 i25 5 -5 5 -7/ (napropamide) (23), which is prepared from 1-naphthol, is used as a herbicide (61). Another agricultural chemical, 1-naphthoxyacetic 2Lcid[2976-75-2] (24), is prepared by stirring 1-naphthol with monochloroacetic acid and sodium hydroxide in water at 100—110°C for several minutes. After treatment with concentrated HCl about 94% of the product is obtained (62). 

Foi glycine (211), two production methods have been employed Stieckei s process and amination of monochloroacetic acid. 

The dye has been degraded by a fusion with caustic potash and the degradation products identified as various o-anilinyl mercaptans. They were identified and characterized by condensation with monochloroacetic acid to give the thioglycohc acids which, on acidification, were converted to well-defined crystalline lactams (2—4) together with a small amount of ji)-aminobenzoic acid. 

Commercial monochloroacetic acid contains many other organic acids, particularly dichloroacetic acid [79 3-6] CI2CHCOOH, which has to be completely converted iato sulfur derivatives to avoid residual chlorine compounds which are harmful for cosmetic apphcations (8). Thioglycohc acid, which has to meet cosmetic specifications, must be free of metal impurities, and must be pure enough to avoid color and odor problems. 

Generally, monochloroacetic acid [79-11-8] (MCA) is added to the reaction slurry containing sufficient excess sodium hydroxide to neutralize the MCA and effect its reaction. The use of esters of MCA has also been reported (52). Common reaction diluents are isopropyl alcohol, /-butyl alcohol, or ethyl alcohol (53,54). Dimethoxyethane has also been reported to be effective (55). The product is isolated and washed with aqueous alcohol or acetone to remove by-product salts. Unpurified cmde grades are generally prepared in the absence of diluents (56—59). 

Oxidation. Atmospheric oxidation of 1,2-dichloroethane at room or reflux temperatures generates some hydrogen chloride and results in solvent discoloration. A 48-h accelerated oxidation test at reflux temperatures gives only 0.006% hydrogen chloride (22). Addition of 0.1—0.2 wt. % of an amine, eg, diisopropylamine, protects the 1,2-dichloroethane against oxidative breakdown. Photooxidation in the presence of chlorine produces monochloroacetic acid and 1,1,2-trichloroethane (23). 

Oxidation. Monochloroacetic acid [79-11-8] may be synthesized by the reaction of ethylene chlorohydrin with nitric acid [7697-37-2]. Yields of greater than 90% are reported (41). >Beta-chlorolactic acid (3-chloro-2-hydroxypropanoic acid) [1713-85-5] is produced by the reaction of nitric acid with glycerol monochlorohydrin (42). Periodic acid [10450-60-9] and glycerol monochlorohydfin gives chloroacetaldehyde [107-20-0] ia 50% yield (43). 

Beryllium, calcium, boron, and aluminum act in a similar manner. Malonic acid is made from monochloroacetic acid by reaction with potassium cyanide followed by hydrolysis. The acid and the intermediate cyanoacetic acid are used for the synthesis of polymethine dyes, synthetic caffeine, and for the manufacture of diethyl malonate, which is used in the synthesis of barbiturates. Most metals dissolve in aqueous potassium cyanide solutions in the presence of oxygen to form complex cyanides (see Coordination compounds). 

Although usually handled as an aqueous solution, formaldehyde cyanohydrin can be isolated in the anhydrous form by ether extraction, followed by drying and vacuum distillation (23). Pure formaldehyde cyanohydrin tends to be unstable especially at high pH. Small amounts of phosphoric acid or monochloroacetic acid are usually added as a stabiLher. Monochloroacetic acid is especially suited to this purpose because it codistiHs with formaldehyde cyanohydrin (24). Properly purified formaldehyde cyanohydrin has excellent stability (25). 

Molybdenum insoluble compounds Molybdenum soluble compounds Monochloroacetic acid Monochlorobenzene (chlorobenzene) Monocrotophos Monomethyl aniline Monomethyl hydrazine Monomethylarsonic acid Morpholine... 

Haloacetic acids dichloroacetic acid (zero) trichloroacetic acid (0.3 mg/L). Monochloroacetic acid, bromoacetic acid, and dibromoacetic acid are regulated with this group but have no MCLGs. 

Mono-carbonsaure, /. monocarboxylic acid, -chloressigsaure, /. monochloroacetic acid, -chlorhydrat, n. monohydrochloride. 

Good conversions are also obtained via a 80% solution of chloroacetic acid in water and a NaOH solution in water (about 50%) which at most a 1 M quantity of free monochloroacetic acid and a 2 M quantity of the aqueous NaOH solution (based on the molar quantity of the nonionic) distilling the water during the reaction, such that the water content of the reaction mixture during the addition of the reaction compounds amounts to 0.3-1.25 wt %. During the reaction there is always added some excess of NaOH with respect to the monochloroacetic acid. The reaction temperature is 70-90°C [15]. 

---