Ethyl adipate

Place 100 g. of adipic acid in a 750 ml. round-bottomed flask and add successively 100 g. (127 ml.) of absolute ethyl alcohol, 250 ml. of sodium-dried benzene and 40 g. (22 ml.) of concentrated sulphuric acid (the last-named cautiously and with gentle swirling of the contents of the flask). Attach a reflux condenser and reflux the mixture gently for 5-6 hours. Pour the reaction mixture into excess of water (2-3 volumes), separate the benzene layer (1), wash it with saturated sodium bicarbonate solution until eflfervescence ceases, then with water, and dry with anhydrous magnesium or calcium sulphate. Remove most of the benzene by distillation under normal pressure until the temperature rises to 100° using the apparatus of Fig. II, 13, 4 but substituting a 250 ml. Claisen flask for the distilling flask then distil under reduced pressure and collect the ethyl adipate at 134-135°/17 mm. The yield is 130 g. 

The above example serves to iUustrate the basis of the procedure employed for the characterisation of aUphatic esters, viz., hydrolysis to, and identification of, the parent acids and alcohols. Most esters are liquids a notable exception is dimethyl oxalate, m.p. 54°. Many have pleasant, often fruit-hke, odours. Many dry esters react with sodium, but less readily than do alcohols hydrogen is evolved particularly on warming, and a sohd sodio derivative may separate on coohng (e.j/., ethyl acetate yields ethyl sodioacetoacetate ethyl adipate gives ethyl sodio cj/cZopentanone carboxylate). 

According to the literature, the product obtained in this manner may contain ethyl adipate. To remove this, the product is cooled to 0° and run slowly into 600 cc. of 10 per cent potassium hydroxide solution maintained at 0° with ice-salt. Water is added until the salt which separates has dissolved, and the cold alkaline solution is extracted twice with 200-cc. portions of ether. The alkaline solution, kept at 0°, is run slowly into 900 cc. of 10 per cent acetic acid solution with stirring, the temperature remaining below 1° (ice-salt). The oil which separates is taken up in 400 cc. of ether, and the aqueous solution is extracted with four 250-cc. portions of ether. The ether extract is washed twice with cold 7 per cent sodium carbonate solution and dried over sodium sulfate. After removal of the ether the residue is distilled, b.p. 7g-8i°/3 mm. The recovery is only 80-85 per cent, and in a well-conducted preparation the ethyl adipate eliminated amounts to less than one per cent of the total product. Unless the preparation has proceeded poorly the tedious purification ordinarily is best omitted. 

If material free from all traces of ethyl adipate is desired, time and material can be saved by omitting the first distillation (observation of the checkers). The toluene solution of the crude 2-carbethoxycyclopentanone is cooled to 0° and added slowly with stirring to 300 cc. of 10 per cent potassium hydroxide solution maintained below r°. Cold water is added until the... 

Carbethoxycyclopentanone has been prepared from ethyl adipate by the action of sodium,sodamide, and sodium ethylate. The method in the above procedure is based upon the work of Cornubcrt and Borrel. ... 

Alcohols are the most frequently formed products of ester hydrogenolysis. The hydrogenation of esters to alcohols is a reversible reaction with alcohol formation favored at high pressure, ester at low pressure (/). Copper chromite is usually the catalyst of choice. Details for the preparation of this catalyst (/7) and a detailed procedure for hydrogenation of ethyl adipate to hexamethylene glycol (/[Pg.80]

Butyl benzyl phthalate Dipropylene glycol dibenzoate cPC Acetyl triethyl citrate Tributoxy ethyl phosphate Dibutoxy ethyl adipate... 

Intramolecular Claisen cyclizations occur with ethyl adipate and pimelate because five- and six-membered rings are formed. 

We have also synthesized bis(2-azidoethyl) adipate (BAEA) by the reaction of bis(2-chloro ethyl) adipate (BCEA) and sodium azide in ethanol medium and characterized the product for solubility, density, refractive index, impact sensitivity, thermal behavior and moisture content [171]. These properties suggest that a part of non-energetic plasticizers, that is, , DEP, DOP etc. can be replaced by BAEA in propellant formulations thereby resulting in increase in their fsp. 

SYNS ADIPIC ACID, BIS(2-ETHOXYETHYL) ESTER DIETHOXY ETHYL ADIPATE HEXANOIC ACID, BIS(2-ETHOXYETHYL) ESTER... 

DIETHOXYETHANE see EJE500 DIETHOXY ETHYL ADIPATE see BJ0225 DIETHOXY-3-KYANPROPYL-METHYLSILAN see COR500... 

An example is the synthesis of ethyl a-ethoxalylpropionate (R = CH,) in 70% yield. Ethyl oxalate and ethyl succinate form ethyl a-ethoxalyl-succinate (83%). In a mixed ester condensation, the use of a more reactive ester, such as the phenyl or biphenyl ester, helps to prevent side reactions. Simple heterocyclic esters, namely, ethyl nicotinate and ethyl 8-quinolinecarboxylate, undergo the mixed ester condensation in good yields. The internal condensation of ethyl adipate to give 2-carbethoxycyclopentanone (Dieckmann reaction) is an example of cyclization (81%). ... 

Sometimes the equilibrium is shifted by removing one of the products. An elegant way of doing this is illustrated by the preparation of ethyl adipate. The dicarboxylic acid adipic acid, an excess of ethyl alcohol, and toluene arc heated with a little sulfuric acid under a distillation column. The lowest boiling component (b.p. 75 ) of the reaction mixture is an azeotrope of water, ethyl alcohol, and toluene fcomoare Sec. 15.6) consequently, as fast as water is formed it is... 

Problem 21.30 Sodium ethoxide converts ethyl adipate into 2-carbethoxycyclo< pentanone (II). This is an example of the Dieckmann condeiisation. 

Methyls are trans in NN, PP cis in OO, QQ, RR (b) NN is resolvable. 22. See p. 1087. 23. (a) Ethyl acetate (b) methacrylic acid (c) phenylacetamide. 24. (a) /i-Propyl formate (b) methyl propionate (c) ethyl acetate. 25. SS, benzyl acetate TT, methyl phenylacetate UU, hydrocinnamic acid, PhCH2CH2COOH. 26. Ethyl anisate. 27. VV, vinyl acetate. 28. (a) Ethyl adipate (b) ethyl ethylphenylmalonate ethyl aoet-amidomalonate. 

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