Ethyl orthocarbonate

ETHYL ORTHOCARBONATE (Orthocarbonic acid, tetraethyl ester) 

Submitted by John D. Roberts and Robert E. McMahon.1 Checked by William S. Johnson and William E. Loeb. 

Caution This preparation should be conducted in a hood to 

A solution of sodium ethoxide is prepared under nitrogen from 70 g. (3.04 gram atoms) of sodium and 2-1. of absolute ethanol (Note 1) in a 3-1. three-necked flask which is equipped with mechanical stirrer, efficient reflux condenser, dropping funnel, and a thermometer which dips below the level of the liquid in the flask. Chloropicrin (100 g., 0.61 mole) (Note 2) is placed in the dropping funnel, and the stirred solution is heated to 58-60° with a water bath. The chloropicrin is added at a rate of 30-35 drops per minute until the reaction becomes self-sustaining (about 20 minutes), at which point the water bath is removed and the balance of the chloropicrin is added at a rate sufficient to maintain the temperature at 58-60° (Note 3). When the addition, which requires nearly 2 hours, is complete, the stirrer is stopped and the mixture is allowed to stand overnight. 

The flask is connected to a 2 by 50 cm. Vigreux column equipped with a total-reflux partial take-off head, and all but about 400 ml. of the ethanol is removed at 200 mm. pressure with a reflux ratio greater than 5 1 (Note 4). 

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Tetraethyl orthocarbonate (ethyl orthocarbonate, tetraethoxy ethane) [78-09-1] M... 

CgHigOj 112-60-7) see lotroxic acid tetraethyf orthocarbonate see under ethyl orthocarbonate... 

Ethylenimine, 30, 38 toxic properties of, 30, 40 Ethyl o-ethoxybenzoate, 32, 75 Ethyl formate, 32, 32 Ethyl glycidyl ether, 31, 3 2-Ethylhexanaldoxime, 32, 67 2-Ethylhexanamide, 32, 65 2-Ethylhexanoic acid, 32, 66 2-Ethylhexanonitrile, 32, 65 Ethylidene bromide, 32, 55 Ethyl iodide, 31, 34 Ethyl isodehydroacetate, 32, 76 Ethyl lactate, 31, 59, 60 5-ETHYL-2-METHYLPYRIDINE, 30, 41 Ethyl orthocarbonate, 32, 68 Ethyl orthoformate, 32, 5 Ethyl orthosilicate, 32, 5 Ethyl phenylazoacetoacetate, 32, 85 Ethyl phenylcyanoacetate, 30,43,80 Ethyl 0-phenyl-/3-cyanopropionate, 30, 84... 

The above procedure is essentially that of Tieckelmann and Post.3 Ethyl orthocarbonate has been prepared by the reaction of chloropicrin and sodium ethoxide by Bassett4 and Rose.5 Thiocarbonyl perchloride has been reported 3 6 to react with sodium ethoxide to give good yields of ethyl orthocarbonate. 

Tshitschibabin synthesis involving the reaction of a Grignard reagent with ethyl orthocarbonate [18, 206]. 

Orthocarbonate. A derivative of the hypothetical orthocarbonic acid, as ethyl orthocarbonate, C(OC2H6)4. The common inorganic carbonates are metacarbonates, derived from metacarbonic acid, H2C03. 

Ethyl orthocarbonate, 32, 68 Ethyl orthoforroate, 32, 5 35, 65 Ethyl orthosilicate, 32, 5 Ethyl 8, 8-pentamethyleneglyci-DATE, 34, 54... 

Ethyl orthoformate is hydrolyzed approximately six powers of ten faster than diethyl formal [158]. Obviously, substitution of another H by C2 Hs O causes further resonance stabilization of the alkoxycarbonium ion intermediate which is formed in the rate-determining step. Rate coefficients and Arrhenius parameters for ethyl orthoformate and ethyl orthobenzoate are similar (Table 12). Quite unexpectedly, ethyl orthocarbonate is hydrolyzed six times more slowly than ethyl orthoformate. 

The hydrolyses of ethyl orthoacetate, ethyl ortho propionate, and ethyl orthocarbonate in aqueous solutions undergo general catalysis by acids [158]. On the other hand, general acid catalysis appears to be absent in the hydrolyses of orthoformates and orthobenzoates if the reactions are carried out in water or in 20 % dioxane—water [158, 28], General acid catalysis can be observed in the hydrolyses of these substrates in solvents with higher percentages of dioxane [28] or in 70 % methanol—water [169],... 

If the hydrolysis of methyl orthobenzoate in weakly acidic solution is carried out in the presence of various amounts of added nucleophiles, such as hydroxylamine or semicarbazide, a considerable fraction of the orthoester is transformed to the product of the reaction with the amine rather than to methyl benzoate, while the rate coefficient remains unchanged [183]. Similarly, the rate of hydrolysis of ethyl orthocarbonate in aqueous cacodylic acid buffer is the same in the presence of 0.04 M NaC104 and of 0.04 M Nal [192]. Thus, nucleophilic catalysis is absent even under conditions when general acid catalysis is effective. 

The hydrolyses of ethyl orthoacetate, ethyl orthopropionate, and ethyl orthocarbonate must occur with rate-determining proton transfer (A-SE2) even in purely aqueous solution. A solvent isotope effect of kH/kD = 0.7 has been found for ethyl orthocarbonate [159, 184]. 

Incorrect Methyl ether Ethyl sulfate Phenyl ether Methyl oxalate Ethyl malonate Benzoyl peroxide Ethyl orthofonnate Ethyl orthocarbonate... 

That the situation previously was highly confused is evident from the following entries in the index of Org. Syn., Coll. Vol., 4 Diethyl oxalate and Diethyl malonate" (both correct), but Ethyl orthofonnate" and Ethyl orthocarbonate (both incorrect). The following entry is describable as a double error Triethyl orthofonnate, see Ethyl orthofonnate. To locate all references to a given ester, it is thus necessary to search under two names. We urge suppliers to revise their catalogs in accordance with the rule cited. In this book we do not even list, with cross references, names which we consider to be incorrect. 

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