Chemical elements
  Carbon
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Methane
      Ethylene
      Acetylene
      Coal-Gas
      Carbon Tetrafluoride
      Tetrafluoromethane
      Carbon Tetrachloride
      Tetrachloromethane
      Carbon Tetrabromide
      Tetrabromomethane
      Carbon Tetraiodide
      Tetraiodomethane
      Carbon Oxychloride
      Carbonyl Chloride
      Phosgene
      Carbon Oxybromide
      Carbonyl Bromide
      Carbon Suboxide
      Carbon Monoxide
      Carbon Dioxide
      Percarbonic Acid
      Carbamic Acid
      Carbamide
      Urea
      Carbon Disulphide
      Carbonyl Sulphide
      Carbon Oxysulphide
      Thiocarbonyl Chloride
      Thiocarbonic Acid
      Thiocarbamic acid
      Thiourea
      Thiocarbamide
      Perthiocarbonates
      Carbon Monosulphide
      Carbon Subsulphide
      Carbon Sulphidoselenide
      Carbon Sulphidotelluride
      Carbon Nitrides
      Cyanogen
      Dicyanogen
      Hydrocyanic Acid
      Prussic Acid
      Cyanogen Chloride
      Chlorocyanogen
      Cyanogen Bromide
      Bromocyanogen
      Cyanogen Iodide
      Iodocyanogen
      Polymerised Cyanogen Halides
      Cyanamide
      Cyanic Acid
      Cyanuric Acid
      Cyamelide
      Fulminic Acid
      Thiocyanic Acid
      Sulphocyanic Acid
      Isoperthiocyanic Acid
      Cyanogen Sulphide
      Thiocyanic Anhydride
    Diamonds
    Graphite
    Amorphous Carbon
    Coal

Chemical Properties of Carbon





Compounds of Carbon with Hydrogen

Hydrocarbons

Carbon forms with hydrogen a large number and variety of compounds known as hydrocarbons. The existence of these many compounds depends on the union of carbon atoms with each other, which may result in the formation of open-chain or cyclic hydrocarbons. Examples of the latter are:

BenzeneNaphthaleneAnthracene
Benzene
C6H6
Naphthalene
C10H8
Anthracene
C14H10


Most of the hydrocarbons find a place only in the study of "organic" chemistry; and it will be sufficient here to notice the main types of open-chain hydrocarbons, and describe in detail the properties of a few typical examples.

The simplest hydrocarbon is methane or marsh-gas, CH4; it is the first representative of a series of saturated, open-chain hydrocarbons, which may be represented thus:

MethaneEthanePropane
Methane
CH3-H
Ethane
CH3-CH3
Propane
CH3-CH2-CH3


have the general formula CnH2n+2, are known as the paraffin hydrocarbons.

When four or more carbon atoms are present in the molecule, branched chains may occur, with the phenomenon of isomerism. For example, there are two hydrocarbons of the formula C4H10:

Normal butane – CH3-CH2-CH2-CH3;
Isobutane - Isobutane
and three of the formula C5H12:
Normal pentane - CH3-CH2-CH2-CH2-CH3
Isopentane - Isopentane
Tetramethylmethane - Tetramethylmethane

The normal paraffins constitute an homologous series in which is shown a gradation in physical properties from member to member, thus:

B.P. (Atm. pressure)Density
Normal pentaneC5H1237° C.0.627 at 14° C
Normal hexaneC6H1469° C.0.658 at 20° C
Normal heptaneC7H1698° C.0.683 at 20° C
Normal octaneC8H18125° C.0.702 at 20° C
Normal nonaneC9H20150° C.0.718 at 20° C
Normal decaneC10H22173° C.0.730 at 20° C


The boiling-points of the normal paraffins are higher than those of their isomers, e.g.

Normal butaneB.P. +1° C
IsobutaneB.P.-17° C
Normal pentaneB.P.+37° C
IsopentaneB.P.+31° C
TetramethylmethaneB.P.+10° C


These differences may be attributed to the greater compactness of the branched as compared with the unbranched carbon chains.

Since methylene, CH2, is unknown, the hydrocarbon ethylene, C2H4, is the first of the olefine series, whose general formula is cnh2n. These compounds contain two atoms of hydrogen fewer than the corresponding paraffin hydrocarbons. The two adjacent carbon atoms from each of which a hydrogen atom is lacking, are formulated as joined together by a double bond. In the case of olefine hydrocarbons containing four or more carbon atoms isomerism occurs owing to the double bond occupying different positions. The following are the constitutional formulae for the oiefines C2H4, C3H4, and C6H8:

Ethylene - HC=CH
Propylene - CH3-CH=CH2
α-Butyleno - CH3-CH2-CH=CH2
β-Butylene - CH3-CH=CH-CH3
γ-Butylene - Butylene

The olefine hydrocarbons are unsaturated, i.e. they form additive compounds which are paraffin hydrocarbons or their derivatives. In this process the double bond is ruptured, thus:

H2C=CH2 + Cl2 = ClH2C-CH2Cl
or Ethylene → Ethylene dichloride or symmetrical dichlorethane.

Acetylene, C2H2, is the first of a third series of hydrocarbons, named after the first member, and having the general formula CnH2n-2. These contain a triple bond and unite with four hydrogen atoms or their equivalent, forming paraffin hydrocarbons or their derivatives:

Acetylene - HCCH
Allylene, Methyl-acetylene - CH3CCH
Crotonylene, Dimethyl-acetylene - CH3CCCH3, etc.

Isomeric with the acetylenes are the di-olefines, e.g.

Allene or symmetrical allylene: CH2=C=CH2.

Olefine-acetylenes are known, e.g. CH2=CH-CCH, and di-acetylenes, e.g. HCC-CCH.


Carbon and the Halogens

Carbon Halides

Numerous halides of carbon are theoretically capable of existence. Not only may successive hydrogen atoms of the many hydrocarbons be replaced by halogen atoms to form substitution derivatives, each series of which ends in a carbon halide, but mixed halide derivatives may also exist. The formation of halogen derivatives of methane by substitution, viz. the series of compounds CH3Cl, CH2Cl2, CHCl3, CCl4, has already been noticed, as well as that of additive compounds, such as C2H4Cl2 and C2H2Cl4, by ethylene and acetylene respectively.

The present study will be limited to halides containing a single carbon atom, i.e. to the four compounds CF4, CCl4, CBr4, CI4.

Carbon Oxyhalides

Just as the carbon tetrahalides, CX4, may be regarded as the halides - or the halanhydrides - of orthocarbonic acid, C(OH)4, so the oxy-halides, COX2 are the halides of metacarbonic acid, CO(OH)2.

Carbon and the Oxygen Group

Oxides of Carbon

The two important oxides of carbon, carbon monoxide, CO, and carbon dioxide, CO2, were for many years the only known oxides. In 1873 the oxide C4O3 was obtained by Brodie by subjecting carbon monoxide to prolonged electric discharges; and in 1877 Berthelot produced C8O3 by heating Brodie's oxide to 300°-400° C. In 1906 Diels and Wolf obtained C3O2, a substance which has aroused much interest. Mellitic anhydride is C12O9; an unsuccessful attempt has been made to prepare dicarbon dioxide, CO:CO.

Amino-derivatives of Carbonic Acid

When the hydroxyl groups of carbonic acid are replaced successively by amino- (NH2) groups there are produced respectively carbamic acid and carbamide.

Carbonic acid: HO-CO-OH
Carbamic acid: HO-CO-NH2
Carbamide: NH2-CO-NH2
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