Alcohols - a separate class of organic compounds that contain in their composition one or more hydroxyl group.Depending on the number of OH groups of these oxygenates are divided into monohydric alcohols, trihydric, etc.Most often, these complex substances is considered as derivatives of hydrocarbons whose molecules have evolved sinceone or more hydrogen atoms are substituted for a hydroxyl group.
The simplest members of this class are monohydric alcohols, the general formula of which is as follows: R-OH or Cn + H 2n + 1OH.
homologous series of compounds starting with methyl alcohol or methanol (CH3OH), followed by going Ethanol (C2H5OH), then propanol (S3N7ON) etc.
for wine characteristic isomerism carbon skeleton and functional groups.
Monohydric alcohols exhibit such physical properties:
- alcohols containing up to 15 carbon atoms - the liquid 15 or more - the solids.
- Solubility in water is dependent on the molecular weight, the higher it is, the worse the alcohol dissolves water.For example, lower alcohols (up propanol) are miscible with water in all proportions, and the higher is practically insoluble in it.
- Boiling also increases with increasing atomic weight, e.g., t heated.CH3OH = 65 ° C, and t is heated.C2H5OH = 78 ° C.
- higher boiling point, the lower volatility, i.e.bad stuff evaporates.
These physical properties of saturated alcohols with one hydroxyl group can be explained by the occurrence of intermolecular hydrogen bonding between individual molecules of the compound or alcohol and water.
monoalcohols are able to engage in such chemical reactions:
- burning - the flame of light, heat is: C2H5OH + 3O2 - 2CO2 + 2H2O.
- Replacement - reacting alkanols with active metals, the reaction products are unstable compounds - alcoholates, - ability to decompose water: 2S2N5ON + 2K - 2S2N5OK + H2.
- Interaction with hydrohalic acids: C2H5OH + HBr - S2N5Br + N2O.
- esterification with organic and inorganic acids, resulting in an ester.
- oxidation, wherein the aldehyde or ketone.
- dehydration.This reaction occurs under heating by using catalyst.Intramolecular dehydration at lower alcohols occurs Zaitsev rule, the result of this reaction is the formation of water and unsaturated hydrocarbon.When an intermolecular dehydration reaction products are ethers and water.
The chemical properties of alcohol, it can be concluded that the monoalcohols - is amphoteric compounds, asthey may react with the alkali metals, showing weak acidic properties and with a hydrogen halide, showing basic properties.All chemical reactions occur with the rupture of the O-H and C-O.
thus limiting monoalcohols - a complex compound with one OH group not having free valences after the formation of C-C bond is weak and properties and acids and bases.Due to their physical and chemical properties, they are widely used in organic synthesis, in the manufacture of solvents, fuel additives, as well as in food industry, medicine, cosmetics (ethanol).
