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case of the polybasic acids, all the hydrogen atoms can be replaced in this way, and the compounds formed are known as " neutral esters." If, however, some of the hydrogen of the acid remain undisplaced, then " acid esters " result. These acid esters retain some of the characteristic properties of the acids, forming, for example, salts, with basic oxides. Esters may be prepared by See also:

HEATING

heating the See also:

SILVER

silver See also:

salt of an acid with an alkyl iodide; by heating the alcohols or alcoholates with an acid chloride; by distilling the anhydrous See also:

SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium salt of an acid with a mixture of the alcohol and concentrated sulphuric acid; or by heating for some See also:

HOURS, CANONICAL

hours on the water See also:

bath, a mixture of an acid and an alcohol, with a small quantity of hydrochloric or sulphuric acids (E. See also:

Fischer and A. Speier, Ber., 1896, 28, p. 3252). The esters of the aliphatic and aromatic acids are colourless neutral liquids, which are generally insoluble in water, nii' readily dissolve in alcohol and See also:

ETHER, (C2H5)2O

ether. Many possess a fragrant odour and are prepared in large quantities for use as artificial See also:

FRUIT (through the French from the Lat. fructus; frui, to enjoy)

fruit essences. They hydrolyse readily when boiled with solutions of See also:

CAUSTIC (Gr. rcavvraubs, burning)

caustic alkalies or See also:

MINERAL

mineral acids, yielding the constituent acid and alcohol. When heated with See also:

AMMONIA (NH3)

ammonia, they yield acid amides (q.v.). They See also:

FORM (Lat. forma)

form unstable addition products with sodium ethylate or methylate.

With the Grignard reagent, they 796 form addition compounds which on the addition of water yield See also:

TERTIARY

tertiary alcohols, except in the case of See also:

ETHYL

ethyl formate, where a secondary alcohol is obtained. • /OMgBr GOMgBr RN R•CO2C2H5 --> R•C—OC2H5 - R•C R' —>R'—yC•OH. ~R' R'~ zOMer /OMgBr R, H•CO2C2H5 –~ H•C\OC2••5 - H•C\R' R,>CH.OH. R' N. Menschutkin (Ber., 1882, 15, p. 1445; See also:

Ann., 1879, 195, p• 334) examined the See also:

RATE

rate of esterification of many acids with alcohols. It was found that the normal See also:

PRIMARY

primary alcohols were all esterified at about the same rate, the secondary alcohols more slowly than the primary, and the tertiary alcohols still more slowly. The investigation also showed that the nature of the acid used affected the result, for in an homologous See also:

SERIES (a Latin word from serere, to join)

series of acids it was found that as the See also:

MOLECULE (from mod. Lat. molecula, the diminutive of moles, a mass)

molecule of the acid became more complex, the rate of esterification became less. The formation of an ester by the interaction of an acid with an alcohol is a " reversible " or " balanced " See also:

ACTION

action, for as M. See also:

BERTHELOT, MARCELLIN PIERRE EUGENE (1827–1907)

Berthelot and L. Nan de St Gilles (Ann. See also:

CHIN

Chin.

Phys., 1862 (3), 65, p. 385 et seq.) have shown in the case of the formation of ethyl acetate from ethyl alcohol and acetic acid, a point of See also:

EQUILIBRIUM (from the Lat. aequus, equal, and libra, a balance)

equilibrium is reached, beyond which the reacting See also:

SYSTEM

system cannot pass, unless the system be disturbed in some way by the removal of one of the See also:

pro-ducts of the reaction. V. See also:

Meyer (Ber., 1894, 27, p. 510 et seq.) showed that in benzenoid compounds ortho-substituents exert a See also:

GREAT

great hindering effect on the esterification of alcohols by acids in the presence of hydrochloric acid, this hindering being particularly marked when two substituents are See also:

PRESENT

present in the ortho positions to the carboxyl group. In such a case the ester is best prepared by the action of an alkyl halide on the silver salt of the acid, and when once prepared, can only be hydrolysed with great difficulty. Ethyl formate, H•CO2C2H5, boils at 55° C. and has been used in the artificial preparation of See also:

rum. Ethyl acetate (acetic ether), CHa•CO2C2H5, boils at 75° C. Isoamylisovalerate, C4H9•CO2C5Hn, boils at 196° C. and has an odour of apples. Ethyl butyrate, C,H7•CO2C2H5, boils at 121 ° C. and has an odour of pineapple. The fats (q.v.) and waxes (q.v.) are the esters of the higher fatty acids and alcohols. The esters of the higher fatty acids, when distilled under atmospheric pressure, are decomposed, and yield an See also:

OLEFINE

olefine and a fatty acid.

Esters of the mineral acids are also known and may be prepared by the See also:

ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary methods as given above. The neutral esters are as a See also:

RULE

rule insoluble in water and distil unchanged; on the other See also:

hand, the acid esters are generally soluble in water, are non-volatile, and form salts with bases. Ethyl hydrogen sulphate (sulphovinic acid), C2H5•HSO4, is obtained by the action of concentrated sulphuric acid on alcohol. The ester is separated from the See also:

SOLUTION (from Lat. solvere, to loosen, dissolve)

solution by means of its See also:

BARIUM (symbol Ba, atomic weight 137'37 [0=16])

barium salt, and the salt decomposed by the addition of the calculated amount of sulphuric acid. It is a colourless oily liquid of strongly acid reaction; its aqueous solution decomposes on See also:

STANDING

standing and on heating it forms diethyl sulphate and sulphuric acid. Dimethyl sulphate, (CHa)2SO4, is a colourless liquid which boils at 187°-188° C., with partial decomposition. It is used as a methylating See also:

AGENT (from Lat. agere, to act)

agent (F. See also:

ULLMANN, KARL (1796-1865)

Ullmann). Great care should be taken in using dimethyl and diethyl sulphates, as the See also:

RESPIRATORY

respiratory See also:

ORGANS

organs are affected by the vapours, leading to severe attacks of See also:

PNEUMONIA (Gr. ?rveu AMP, lung)

pneumonia. Ethyl nitrate, C2H5.ONO2, is a colourless liquid which boils at 86.3°C. It is pre-pared by the action of nitric acid on ethyl alcohol (some See also:

UREA, or CARBAMIDE, CO(NH2)2

urea being added to the nitric acid, in See also:

order to destroy any nitrous acid that might be produced in secondary reactions and which, if not removed, would cause explosive decomposition of the ethyl nitrate). It See also:

burns with a See also:

white See also:

FLAME (Lat. flamma; the root flag- appears in flagrare, to burn, blaze, and Gr. d, XEryew)

flame and is soluble in water.

When heated with ammonia it yields ethylamine nitrate, and when reduced with See also:

TIN (Lat.- stannum, whence the chemical symbol " Sn "; atomic weight =117.6, 0=16)

tin and hydrochloric acid it forms See also:

HYDROXYLAMINE, NH2OH

hydroxylamine (q.v.) (W. C. Lossen). Ethyl nitrite, C,H5.ONO, is a liquid which boils at 18° C.; the crude product obtained by distilling a mixture of alcohol, sulphuric and nitric acids and See also:

COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper turnings is used in See also:

MEDICINE

medicine under the name of " sweet See also:

SPIRITS

spirits of See also:

NITRE

nitre." Amyl nitrite, C5HI1.ONO, boils at 96° C. and is used in the preparation of the anhydrous diazonium salts (E. Knoevenagel, Ber., 1890, 23, p. 2094). It is also used in medicine.

End of Article: ESTERS

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