Solvents

under a solvent (often also called solvents) one understands a liquid, which can loosen gases , other liquids or solids, without it comes thereby to chemical reactions between solved material and solving liquid.

containing solvent, solvent-freely

frequent the term solvent reduced to materials, the unpleasant Smells, health and environmental damage to cause can.

In this sense designates solvent-freely then colors, adhesives, lacquers or glazes, which are solved in water and contain less than 3% water-mixable solvents, while the term designates containing solvent products, those synthetic substances such as acetone, Glycolether, alcohols, gasoline or aromatics contain.

solve themselves

chemistry polar materials well in polar solvents (z. B. Salts in water). Nonpolar materials separate well in nonpolar solvents (z. B.nonpolar organic materials in benzene or Ether).

Solvents are usually divided according to their physical characteristics in classes. Such organization criteria e.g. are:

• Boiling point
• flash point
• evaporability
• viscosity
• polarity
• CH acidity

Aproti solvents

aprotisch nonpolar

an alkane is nonpolar. The hydrogen atoms are all equal firmly to the carbon chain bound and can therefore as protons only very heavy and under education very reactive Carbanionen abdissoziieren for its part. This makes all materials of these groups into one another easily soluble, it is very lipophilic(actually still more lipophilically as the very weakly polar, named-giving fats), and very much hydrophob. But water cannot only not separate, but all other strongly polar materials also not, like e.g. kurzkettige alcohols, hydrogen chloride or salts. Inthe liquid the particles are only held together by Van that Waals forces. Therefore the boiling temperatures fail mass compared with molecule size and - substantially lower than with permanent dipoles at this group of materials.

Representatives of this group are:

• Alkanes
• of alkenes, alkines
• Benzen and Aromatics with aliphatic and aromatic substituents
• of by halo genius ores of hydrocarbons (each hydrogen atom is by a same halogen - atom substitutes), e.g. Carbon tetrachloride, hexadecimal fluorine benzene
• further, completely symmetrically built molecules, like Tetramethylsilan, Bleitetraethyl

• similar to Kohlenstoffdisulfid and, with high pressures, also carbon dioxide

aprotisch polar

the molecule is however asymmetrical substituted, particularly with strongly polarizing functional groups like the Carbonylgruppe or the Nitrilgruppe, which possess however no X - H - connections ( X ≠ C), then points the molecule a dipole momentup, between-molecularly now thus electrostatic attraction of durable dipoles steps to the still existing, but overlaid totally Van that Waals forces in addition. This has a substantial increase of the boiling point to the consequence, and in many cases a degradation of the miscibility with nonpolar solvents, as well asan improvement of the solubility of and in polar materials.

Examples:

• Ether
• ester, Säureanhydride
• Ketone, e.g. Acetone
• tertiary amines
• Pyridin, Furan, Thiophen
• 1,1,1-Trichlorethan, chloroform and further asymmetrically halo genius ores of hydrocarbons (FCKW, Halothan)
• dimethyl sulfate, Imsol
• anisole
• Nitromethan

dipolar aprotisch

examples:

• Dimethylformamide
• Dimethylsulfoxid, HMPTA
• Dimethylcarbonat, Tetramethylharnstoff, Tetraethylharnstoff DMPU DMEU

of pro tables solvents

as soon as a functional group has a molecule, from the hydrogen atoms in the molecule as protonsabgespalten will can (dissociation), speak one of per tables a solvent.

Most important per tables the solvent is water, which (simplified) in a proton and a hydroxide - ion dissociates.

Further per tables solvents e.g. place. Alcohols and carbonic acids. Here takes placethe splitting off of the proton always at the OH-group, since the electronegative oxygen can take up the developing negative charge well.

The measure, in which the respective solvent dissociates, is determined by the acidity. It is to be noted that also at carbonbound hydrogen atoms as protons abgespalten will can (CH acidity), the acidity of these connections however are too small, in order to permit a considerable dissociation in neutral medium. The release of these protons is possible only by strong Basen.

An exception form stillnot aldehydes mentioned: A O-H-connection is present , it would nearly never be polar aprotisch thereby, by the very strong electron suction, that the oxygen atom on the Carbonyl C atom exercises (- I-effect) becomes however the CH connection so strongly in thempolarized that the hydrogen can be split off as proton. Therefore aldehydes in aqueous solutions react also weakly sourly.

Polar per tables solvents loosen for their part salts, which can dissociate then in anions and cations. Likewise the solubility of polar connections is good, against itthe solubility of nonpolar connections is small.

Pro table are:

• Water, the probably most important solvent at all
• methanol, ethanol and other alcohols (the more largely the C-stand, the less strongly pronouncedly is the polar character, then e.g. is Cholesterin. an alcohol howevernevertheless strongly lipophilically)
• primary and secondary amines
• carbonic acids: Formic acid, acetic acid
• form amide

table with solvents and its data

application

solvent are differently strongly water-endangering, flammable and injurious to health.

When ecological building a large weight is put to used solvents in the kind. Often there are solvent-free with consumer products and/or. - poor alternatives.

With open application that evaporateslargest part of the solvents into the ambient air. With the employment in closed systems the predominant quantity is recovered.

Hydrocarbons from solvents work at ground level as forerunner substances for the ozone formation and are like that along-causing for the summer smog.