Chloroacetate esters

CgHjClaOj. M.p. 155°C. Used as a selective herbicide. It is made from 2,4,5-trichloro-pheno) and sodium chloroacetate. Ester sprays and combined ester sprays with 2,4-D are available. 2,4,5-T products are of particular value in that they control many woody species, and eradicate perennial weeds such as nettles in pastures. 

The glycidic esters are of interest primarily because upon hydrolysis aud decarboxylation they aflFord aldehydes (if ClCHjCOOEt is used) or ketones (if substituted chloroacetic esters- ClCHRCOOEt are employed) having a higher carbon content than the original aldehyde or ketone. Thus (I) gives o-phenyl-propionaldehyde or hydratropaldehyde (II) ... 

It is also possible to convert carbonyl groups into oxirane rings with cenain carbenoid synthons. The classical Darzens reaction, which involves addition of anions of a-chloroacetic esters, has been replaced by the addition of sulfonium ylides (R. Sowada, 1971 C.R. Johnson, 1979). 

Other interesting regioselective reactions are carried out within the synthesis of nitrofurantoin. Benzaidehyde semicarbazone substitutes chlorine in chloroacetic ester with the most nucleophilic hydrazone nitrogen atom. Transamidation of the ester occurs with the di-protic outer nitrogen atom. Only one nucleophilic nitrogen atom remains in the cyclization product and reacts exclusively with carbonyl compounds. 

In 1891, Miolati (75) confirmed the cyclic formula of Liebermann and Lange by preparing the compound by three new pathways (1) reaction of CS2 on thiohydantoin, (2) condensation of ammonium dithiocarbamate with chloroacetic ester, (3) reaction of HjS on thiocyanoacetic acid. 

Much of the chloroacetyl chloride produced is used captively as a reactive intermediate. It is useful in many acylation reactions and in the production of adrenalin [51-43-4] diazepam [439-15-5] chloroacetophenone [532-27-4] chloroacetate esters, and chloroacetic anhydride [541-88-8]. A major use is in the production of chloroacetamide herbicides (3) such as alachlor [15972-60-8]. 

Two chloroacetate esters of industrial importance are methyl chloroacetate [96-34-4] C2H C102, and ethyl chloroacetate [105-39-5]., Their... 

Chloroacetate esters are usually made by removing water from a mixture of chloroacetic acid and the corresponding alcohol. Reaction of alcohol with chloroacetyl chloride is an anhydrous process which Hberates HCl. Chloroacetic acid will react with olefins in the presence of a catalyst to yield chloroacetate esters. Dichloroacetic and trichloroacetic acid esters are also known. These esters are usehil in synthesis. They are more reactive than the parent acids. Ethyl chloroacetate can be converted to sodium fluoroacetate by reaction with potassium fluoride (see Fluorine compounds, organic). Both methyl and ethyl chloroacetate are used as agricultural and pharmaceutical intermediates, specialty solvents, flavors, and fragrances. Methyl chloroacetate and P ionone undergo a Dar2ens reaction to form an intermediate in the synthesis of Vitamin A. Reaction of methyl chloroacetate with ammonia produces chloroacetamide [79-07-2] C2H ClNO (53). 

Amine-containing cellulose esters, eg, the acetate A/A/-diethylaminoacetate (36) and propionate morpholinobutyrate (35), are of interest because of their unique solubiHty in dilute acid. Such esters are prepared by the addition of the appropriate amine to the cellulose acrylate crotonate esters or by replacement of the chlorine on cellulose acrylate chloroacetate esters with amines. This type of ester has been suggested for use in controlled release, mmen-protected feed supplements for mminants (36,37). 

Chloroacetaldehyde, production from acetaldehyde, 1 105 Chloroacetamide, l 142 herbicides, 13 303 Chloroacetate esters, 1 142 physical properties of, 1 142t Chloroacetic acid, 1 136-139 end use of chlorine, 6 135t physical properties of, l 137t producers, l 139t... 

The formation of cyclopropanes from 7C-deficient alkenes via an initial Michael-type reaction followed by nucleophilic ring closure of the intermediate anion (Scheme 6.26, see also Section 7.3), is catalysed by the addition of quaternary ammonium phase-transfer catalysts [46,47] which affect the stereochemistry of the ring closure (see Chapter 12). For example, equal amounts of (4) and (5) (X1, X2 = CN) are produced in the presence of benzyltriethylammonium chloride, whereas compound (4) predominates in the absence of the catalyst. In contrast, a,p-unsatu-rated ketones or esters and a-chloroacetic esters [e.g. 48] produce the cyclopropanes (6) (Scheme 6.27) stereoselectively under phase-transfer catalysed conditions and in the absence of the catalyst. Phenyl vinyl sulphone reacts with a-chloroacetonitriles to give the non-cyclized Michael adducts (80%) to the almost complete exclusion of the cyclopropanes. 

Cyclopropanation reactions of chloroalkanes with jt-deficient alkenes under basic phase-transfer catalysed conditions have been observed. Thus, for example, chloroacetic esters and chloroacetonitriles undergo Michael-type reactions with acrylic esters and acrylonitriles, the products of which cyclize to give cyclopropanes (see Section 6.4). 

Drees and co-workers synthesized a number of energetic azido plasticizers whose structures are based on those of known nitrate ester plasticizers. EGBAA (3), DEGBAA (4), TMNTA (5) and PETKAA (6) are synthesized from the corresponding chloroacetate esters with sodium azide in DMSO. 

Application of 4-chloroacetic ester 46 (89CCC1336, 03RCB2185, 06S2357) opens access to 6-chloromethylpyrans 47, which are useful for further chemical transformations (e.g., into condensed aminopyrans) due to the presence of the labile chlorine atom (Scheme 3). 

Lipase Catalyzed Kinetic Resolution of Alcohols via Chloroacetate Esters (-)-(lR,2S)-trans-2-Phenylcyclohexano1 and (+)-(lS,2R)-trans-2-Phenyl cyclohexanol... 

Apart from ethyl acetate, the least reactive ester studied is N,0-diacetyl serinamide, which is hydrolyzed in a pH-independent reaction between pH 7 and 8 with a rate coefficient193 of 2.66 x 10-5 sec-1. Salmi and Suonpaa194 and Palomaa et al. 9S, have measured the rates of neutral hydrolysis of a number of chloroacetate esters, and this work has been extended more recently by Euranto and Cleve196-198, who have measured the activation parameters for the hydrolysis of several compounds. Motfat and Hunt199 have obtained the same data for the hydrolysis of a variety of alkyl and aryl trifluoroacetates, and the data for substituted phenyl acetates191 have been plotted in Fig. 14. Most of the available data are collected in Table 27. 

LIPASE-CATALYZED KINETIC RESOLUTION OF ALCOHOLS VIA CHLOROACETATE ESTERS (-)-(1R,2S)-trans-2-PHENYLCYCLOHEXANOL AND (+)-(1S,2R)-trans-2-PHENYLCYCLOHEXANOL... 

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