Diethyl carbonate, formation

Successful results have been obtained (Renfrew and Chaney, 1946) with ethyl formate methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and iso-amyl acetat ethyleneglycol diacetate ethyl monochloro- and trichloro-acetates methyl, n-propyl, n-octyl and n-dodecyl propionates ethyl butyrate n-butyl and n-amyl valerates ethyl laurate ethyl lactate ethyl acetoacetate diethyl carbonate dimethyl and diethyl oxalates diethyl malonate diethyl adipate di-n-butyl tartrate ethyl phenylacetate methyl and ethyl benzoates methyl and ethyl salicylates diethyl and di-n-butyl phthalates. The method fails for vinyl acetate, ieri.-butyl acetate, n-octadecyl propionate, ethyl and >i-butyl stearate, phenyl, benzyl- and guaicol-acetate, methyl and ethyl cinnamate, diethyl sulphate and ethyl p-aminobenzoate. 

Mixed Claisen condensations (Section 21.3) Diethyl carbonate, diethyl oxalate, ethyl formate, and benzoate esters cannot form ester enolates but can act as acylating agents toward other ester enolates. 

To the cooled (room temperature) reaction mixture, glacial acetic acid (15 ml) is added dropwise with stirring (formation of pasty solid), followed by 50 ml of ice-cold water (dissolution of the solid). The benzene layer is separated, the aqueous layer is extracted three times with 25-ml portions of benzene, and the combined benzene extracts are washed three times with 25-ml portions of cold water. Benzene is removed by distillation at atmospheric pressure, and excess diethyl carbonate is removed by distillation under aspirator pressure. The residue is distilled under vacuum, affording 2-carbethoxycyclooctanone, bp 85-8770.1 mm, 1.4795-1,4800, about 14 g (94%). 

Cyclooctanone, condensation with diethyl carbonate, 47, 20 Cyclopentadiene, adduct formation with 1,2,3-benzothiadiazole 1,1-diox-ide, 47, 8... 

According to the Marcus theory [64] for outer-sphere reactions, there is good correlation between the heterogeneous (electrode) and homogeneous (solution) rate constants. This is the theoretical basis for the proposed use of hydrated-electron rate constants (ke) as a criterion for the reactivity of an electrolyte component towards lithium or any electrode at lithium potential. Table 1 shows rate-constant values for selected materials that are relevant to SE1 formation and to lithium batteries. Although many important materials are missing (such as PC, EC, diethyl carbonate (DEC), LiPF6, etc.), much can be learned from a careful study of this table (and its sources). 

The use of an extra mole of lutidine and rapid addition of diethyl carbonate both decrease formation of urethane. The use of the dry ice bath to cool the reaction mixture permits rapid addition of diethyl carbonate without excessive foaming. If urethane is formed from the diethyl carbonate and ammonia, the yield of product is decreased and the distillation is difficult. 

In this case, the presence of the acid HRu(C0) I, as depicted in Scheme 3, also seems to play an essential role in the activation of the C-0 bond of the different ether derivatives and in the evolution of the alkyl and acyl intermediates toward hydrogenation and carbonylation products. The formation of diethyl carbonate may be related to the substitution of an I" by an EtO group in HRu(CO)2l3 promoted by the [CH(0Et)2] base. The ethoxy intermediate is then carbonylated to an ethoxycarbonyl derivative and transformed into diethyl carbonate by a nucleophilic attack by ethanol (Scheme 4). 

Scheme 4 - Formation of diethyl carbonate from ethyl orthoformate catalyzed by HRu(CO)3l3...

Cyclic carbonates are not commercially available and have to be synthesized prior to use. As a result, commercially available carbonates such as diethyl carbonate [55-57] or diphenyl carbonate [93] were evaluated in polycondensation reactions with diols to prepare polycarbonates since they allow a broader spectrum of polymers to be accessed. Unfortunately, polymerizations employing diethyl carbonate require the use of an excess diethyl carbonate [55]. Nevertheless, polymers with molecular weight of 40kDa were achieved within 16 h. Also, the polymerization of diphenyl carbonate with butane-1,4-diol or hexane-1,6-diol via the formation of a cyclic dimer produced polymers with molecular weights ranging from 119 to 339kDa [93]. 

Exercise 16-9 Write equations to show the steps involved in the following carbonyl-addition reactions (a) base-catalyzed addition of ethanol to ethanal to form the corresponding hemiacetal, 1-ethoxyethanol (b) formation of 1-ethoxyethanol from ethanol and ethanal, but under conditions of acid catalysis (c) formation of 1,1-diethoxyethane from 1-ethoxyethanol and ethanol with an acid catalyst and (d) formation of diethyl carbonate (CH3CH20)2C—0 from ethanol and carbonyl dichloride. 

Lanthanum nitrate, analysis of anhydrous, 5 41 Lead (IV) acetate, 1 47 Lead(II) 0,0 -diethyl dithiophos-phate, 6 142 Lead (IV) oxide, 1 45 Lead(II) thiocyanate, 1 85 Lithium amide, 2 135 Lithium carbonate, formation of, from lithium hydroperoxide 1-hydrate, 5 3 purification of, 1 1 Lithium chloride, anhydrous, 6 154 Lithium hydroperoxide 1-hydrate, 5 1... 

Ethoxycarbonyl moieties may be introduced at the benzylic position by reaction of pyridylmethyl anions with diethyl carbonate <1997S949> or ethyl chloroformate <2004BML1795>. Fries rearrangement of 0-(2-methylpyr-idyl)carbamates has been used to introduce an acetamide group to the benzylic position of 2-methylpyridines <1997SL839>. Treatment of O-pyridylmethylcarbamate 40 with 2.2equiv of LDA at —78 °C leads to the formation of pyridylacetamide 41 in 70% yield (Equation 30). 

Butanone y-butyrolactone Diethyl carbonate Diethyl sulfite Dimethylcarbonate Ethyl acetate Ethyl formate Ethylene carbonate Ethylene glycol sulfite Methyl acetate Methyl formate Nitromethane... 

This section deals only with solvents whose reduction products are insoluble in the presence of lithium ions. The list includes open chain ethers such as diethyl ether, dimethoxy ethane, and other polyethers of the glyme family cyclic ethers such as THF, 2Me-THF, and 1,4-dioxane cyclic ketals such as 1,3-dioxolane and 1,3-dioxane, esters such as y-butyrolactone and methyl formate and alkyl carbonates such as PC, EC, DMC, and ethylmethyl carbonate. This list excludes the esters, ethyl and methyl acetates, and diethyl carbonate, whose reduction products are soluble in them (in spite of the presence of Li ions). Solutions of solvents such as acetonitrile and dimethyl formamide are also not included in this section for the same reasons. Figure 6 presents typical steady state voltammo-grams obtained with gold, platinum, and silver electrodes in Li salt solutions in which solvent reduction products are formed and precipitate at potentials above that of lithium metal deposition. These voltammograms are typical of the above-mentioned solvent groups and are characterized by the following features ... 

PC = propylene carbonate DN = 1,3-dioxolane EC = ethylene carbonate 3-MeS-3 = methyl sulfolane DME = dimethoxy ethane THF = tetrahydrofuran S = sulfolane DMSO = dimethyl sulfoxide, DEE = diethyl ether, 2-Me-F = 2 methyl furan 2-MeDN = 2-methyl 1,3-dioxolane MA = methylacetate DMM = dimethoxymethane 2-MeOTHF = 2 methoxytetrahydrofuran BL = y-butyrolactone NM = nitromethane AN = acetonitrile MF = methyl formate DEC = diethyl carbonate DMC = dimethyl carbonate. 

With respect to the reaction mechanism a nucleophilic attack of the bis(trimethylsilyl)phosphanide anion at the sp -hybridized carbon of diethyl carbonate, followed by an elimination of one molecule of ethoxy trimethylsilane and formation of a still undetected phosphaalkene is supposed. Splitting off a second molecule ethoxytrimethylsilane the P-C double bond of the intermediate is converted into a triple bond thereafter (Eq. 10). 

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