ethers are organic substances, in which the molecules contain hydrocarbon radicals attached to an oxygen atom.Record is as follows: R'-O-R ", wherein R" and R 'are identical or different radicals.
ethers are regarded as derivatives of alcohols.These compounds have a composite name.It uses the title radicals (ascending molecular weight) and, in fact, the word "air" (SN3OSN3 dimethyl ether, methyl ethyl ether S2N5OSN3 and so on).
Symmetrical compounds R-O-R are obtained by intermolecular dehydration of alcohol.In one molecule, wherein the cleavage of the O-H and the other - the C-O.The reaction can be considered as a nucleophilic substitution HO-group (in one molecule) group RO (of another molecule).
Unbalanced Connections R-O-R 'formed by reacting galogenouglevodoroda and alkoxide.
Ethers (unlike their isomeric alcohols) have lower melting and boiling points.With water connection almost do not mix.This is due to the fact that the ethers do not form hydrogen bonds due to the absence in the molecule polar O-H bonds.
compounds are less active.They have a lower capacity to react than alcohols.
Ethers are often used as solvents due to their ability to dissolve many organic substances.
The most important compounds are heterocyclic acidic substances: dioxane, and epoxy (ethylene oxide).
first is a good solvent.Dioxane is miscible with both hydrocarbons and water.Because of these qualities, this compound is also called "organic water."Dioxane is toxic, but the most dangerous of its halogen dibenzoderivatives.
cellulose ethers are the products of substitution of the hydrogen atom in the hydroxyl groups of the macromolecules of cellulose or alkyl acid residues.The synthesis is carried out to impart new properties of substances, in particular, thermoplasticity and solubility.When substituted acid residues form complex, with substituted alkyl residues - simple compounds.
first prepared during the esterification and acylation - by reacting cellulose with inorganic and organic acids, their acid chlorides and anhydrides.The greatest practical importance is attached ksatogenatam.These compounds are prepared by reacting with inorganic acids and their use in the manufacture of cellophane and viscose fibers.Industrial importance and cellulose nitrates.Their use in the preparation of coatings, films, smokeless gunpowder.
Among the compounds obtained by reaction with organic acids are widely used in industry cellulose acetates.Their use in the preparation of synthetic fibers, plastics and film.
There are also mixed cellulose esters.They contain a variety of acyl and alkyl substituents.
properties of cellulose esters depend on the nature of the radical.Value and has a degree of substitution and polymerization.
simple low-substituted compounds are soluble in aqueous alkaline solutions and water.This allows their use as thickeners and stabilizers in emulsions in the oil, paper, textile, food, pharmaceutical and other industries.Highly substituted ethers (complex and simple) are compatible with plasticizers.They are used in the manufacture of plastics and lacquers delivery.
Crown ethers are polyesters containing more oxygen in the ring atoms.Formally, they are treated as products tsiklooligomerizatsii ethylene oxide.A unique property of these compounds is the ability to form complexes with various alkali metal salts.These complexes are formed due to electrostatic interaction.
