Man's physical universe

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"BETTER THINGS" FROM COAL 693

Coal and Lime Are Used to

Prepare Calcium Carbide, Which Is the

Starting-point for Many Important Organic Reactions.

Calcium carbide is

prepared by heating coke with lime in an electric

furnace.

CaO + 3C —>- CaCz + CO

lime coke calcium carbide carbon monoxide

Calcium carbide and water react to form acetylene:

CaC2 + 2H2O —>- C2H2 + Ca(0H)2.

calcium carbide water acetylene calcium hydroxide

Two molecules of acetylene may be polymerized in the presence of a

catalyst to produce monovinyl acetylene, C4H4:

2C2H2 —>- C4H4

acetylene

monovinyl acetylene

Monovinyl acetylene reacts with hydrogen chloride to produce

chloroprene.

HC=C-CH=CH2 + HCl

—>-

H2C = CC1-CH = CH2

monovinyl hydrogen chloroprene

acetylene

chloride

Several molecules of chloroprene may now be polymerized to form

large molecules to produce a plastic material similar to natural rubber

in many respects and superior to it in other respects. This product is

the new synthetic rubber, neoprene, which will be discussed in Section

9 of this Unit.

Acetylene is also the starting-point for the synthesis of ethylene,

acetic acid, acetone, ethyl alcohol, and many other important

compounds.

Calcium carbide offers still other interesting possibilities. For

example, it will combine with nitrogen to form calcium cyanamide,

which may be used directly as a fertilizer or which may be treated with

steam to produce ammonia, which is then used to produce ammonium

salts for fertilizers.

Calcium cyanamide may also be readily converted

into urea, which is used in synthetic plastic manufacture, as a stabilizer

for explosives, and in other important applications. Calcium

cyanamide may also be converted into sodium cyanide, which is used

for the extraction of gold by the cyanide process.

Coal May Be Hydrogenated.

Hydrogen may be combined with coal in the presence of a catalyst

to produce hydrocarbons for use as fuels or raw materials in the organic

chemical industry. The hydrogen may be obtained from water by

the action of coke (the carbon left after removing tar from bituminous

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