Ethers are organic substances formed when a water molecule is taken from two alcohol molecules (ethers) or from an alcohol molecule and an acid molecule (ester esters). Ethers are volatile, poorly soluble in water, they readily dissolve fats. Some of them find application in medicine, for example diethyl, or sulfuric, ether is used for inhalation anesthesia (see Ethyl ether ).
Complex esters are part of essential oils, causing their pleasant odor, are used in the food and perfume industries. Esters include many biologically important substances - nucleic acids , carbohydrates , fats, phosphatides , vitamins, as well as medicines - urethane, salicylate and para-aminobenzoic acid ester (anestezin, novocaine), etc.
Ethers are organic substances formed as a result of abstraction of a water molecule from two alcohol molecules (ethers, or ethers) or from an alcohol molecule and an acid molecule (esters or esters).
Ethers can be considered as substitution products in the water molecule of both hydrogen atoms by hydrocarbon radicals. These radicals may be the same or different (in the latter case, the esters are called mixed). The names of the esters usually derive from the names of the radicals that make up their composition (for example, CH 3 -O-C 2 H 5 -methylethyl ether). According to the Geneva nomenclature, the name of the ether is derived from the name of the hydrocarbon corresponding to the larger radical, with a prefix, which is the name of an alkoxy group with a smaller radical (for example, CH 3 -O-C 3 H 7 -methoxypropane).
Ethers are usually obtained from alcohols by reaction of esterification, i.e., removal of the water molecule under the action of dehydrating agents (sulfuric, phosphoric acids, zinc chloride, copper sulphate, etc.). Ethers derived from lower alcohols boil at a lower temperature than the corresponding alcohols. Dimethyl and methylethyl esters at room temperature are gases starting with diethyl ether-liquid. Ethers easily dissolve organic matter, do not mix with water. This is the basis for the use of their (especially diethyl ether) for extraction.The
Ethers are neutral substances that are quite difficult to react. They do not hydrolyze, and for their decomposition concentrate hydroiodic acid or sodium metal is used when heated (Shorygin reaction). With mineral acids, esters give salts of substituted oxonium. In medicine, there is the use of ethyl (diethyl), "sulfuric", ether; is used for anesthesia (see Ethyl ether).
Esters - derivatives of alcohols in which hydrogen in the hydroxyl is replaced by an acid residue (organic or mineral). By the method of labeled atoms, it was shown that when hydroxides are formed, hydroxyl is split off from the acid, and hydrogen from alcohol. Esters are named for those acids and alcohols whose residues are included in their composition (for example, ethyl acetate-ethyl acetate).
Esters are obtained most often by the interaction of acids and alcohols in the presence of water-withdrawing agents (usually concentrated sulfuric acid), an esterification reaction, less frequently by the action of acid anhydrides on alcohols, the reaction of acid salts with halogen alkyls, acid halides with alcoholates.
Esters of the simplest acids and alcohols are liquids with a pleasant fruity odor. Most of them are poorly soluble in water, well - in organic solvents. Esters easily hydrolyse to form acid and alcohol (saponification reaction). Recovery of esters leads to the formation of alcohols. Under the action of ammonia, the esters are converted to amides.
Esters are quite widespread in nature and largely determine the flavors of flowers, fruits and berries. Many ethers are used in the national economy and medicine. Nitric acid esters are explosives. The isoamyl ester of nitrous acid (amyl nitrite) is used in medicine for angina pectoris as a means of dilating the blood vessels. Some esters of organic acids (isoamyl acetate, ethyl butyrate, etc.) are used to make artificial fruit essences used in the production of confectionery and perfumery. Esters include many biologically important substances - nucleic acids (polyesters of phosphoric acid and nucleosides), fats, some biostimulants (acetylcholine). Esters are many drugs: salicylic acid ester, para-aminobenzoic acid (anesthesin, novocaine), antibiotics, etc.