methanation A method of manufacturing methane from carbon
monoxide or dioxide by highpressure catalytic hydrogenation.
It is often used to improve the
caloriÜc value of town gas.
methane A colourless odourless
gas, CH 4 ; m.p. –182.5°C; b.p. –164°C.
Methane is the simplest hydrocarbon, being the Ürst member of the
*alkane series. It is the main constituent of natural gas (∼99%) and as
such is an important raw material for
producing other organic compounds.
It can be converted into methanol by
catalytic oxidation.
methanide See carbide.
methanoate (formate) A salt or
ester of methanoic acid.
methanoic acid (formic acid) A
colourless pungent liquid, HCOOH;
r.d. 1.2; m.p. 8°C; b.p. 101°C. It can be
made by the action of concentrated
sulphuric acid on the sodium salt
(sodium methanoate), and occurs naturally in ants and stinging nettles.
Methanoic acid is the simplest of the
*carboxylic acids.
methanol (methyl alcohol) A
colourless liquid, CH 3 OH; r.d. 0.79;
m.p. –93.9°C; b.p. 64.96°C. It is made
by catalytic oxidation of methane
(from natural gas) using air.
Methanol is used as a solvent (see
methylated spirits) and as a raw
material for making methanal
(mainly for urea–formaldehyde
resins). It was formerly made by the
dry distillation of wood (hence the
name wood alcohol).
methionine See amino acid.
methoxy group The organic
group CH 3 O–.
methyl acetate See methyl
ethanoate.
methyl alcohol See methanol.
methylamine A colourless Ûammable gas, CH 3 NH 2 ; m.p. –93.5°C; b.p.
–6.3°C. It can be made by a catalytic
reaction between methanol and ammonia and is used in the manufacture of other organic chemicals.
methylated spirits A mixture
consisting mainly of ethanol with
added methanol (∼9.5%), pyridine
(∼0.5%), and blue dye. The additives
are included to make the ethanol undrinkable so that it can be sold without excise duty for use as a solvent
and a fuel (for small spirit stoves).
methylation A chemical reaction
in which a methyl group (CH 3 –) is introduced in a molecule. A particular
example is the replacement of a hydrogen atom by a methyl group, as in
a *Friedel–Crafts reaction.
methylbenzene (toluene) A
colourless liquid, CH 3 C 6 H 5 ; r.d. 0.9;
m.p. –95°C; b.p. 111°C. Methylbenzene is derived from benzene by replacement of a hydrogen atom by a
methyl group. It can be obtained
from coal tar or made from methylcyclohexane (extracted from crude
oil) by catalytic dehydrogenation. Its
main uses are as a solvent and as a
raw material for producing TNT.
methyl bromide See bromomethane.
2-methylbuta-1,3-diene See isoprene.
methyl chloride See
chloromethane.
methyl cyanide See ethanenitrile.
methylene The highly reactive
*carbene, :CH 2 . The divalent CH 2
group in a compound is the methylene group.
methylene chloride See
dichloromethane.
methanation
352
m
www.AzShimi.ir www.AzShimi.com
monoxide or dioxide by highpressure catalytic hydrogenation.
It is often used to improve the
caloriÜc value of town gas.
methane A colourless odourless
gas, CH 4 ; m.p. –182.5°C; b.p. –164°C.
Methane is the simplest hydrocarbon, being the Ürst member of the
*alkane series. It is the main constituent of natural gas (∼99%) and as
such is an important raw material for
producing other organic compounds.
It can be converted into methanol by
catalytic oxidation.
methanide See carbide.
methanoate (formate) A salt or
ester of methanoic acid.
methanoic acid (formic acid) A
colourless pungent liquid, HCOOH;
r.d. 1.2; m.p. 8°C; b.p. 101°C. It can be
made by the action of concentrated
sulphuric acid on the sodium salt
(sodium methanoate), and occurs naturally in ants and stinging nettles.
Methanoic acid is the simplest of the
*carboxylic acids.
methanol (methyl alcohol) A
colourless liquid, CH 3 OH; r.d. 0.79;
m.p. –93.9°C; b.p. 64.96°C. It is made
by catalytic oxidation of methane
(from natural gas) using air.
Methanol is used as a solvent (see
methylated spirits) and as a raw
material for making methanal
(mainly for urea–formaldehyde
resins). It was formerly made by the
dry distillation of wood (hence the
name wood alcohol).
methionine See amino acid.
methoxy group The organic
group CH 3 O–.
methyl acetate See methyl
ethanoate.
methyl alcohol See methanol.
methylamine A colourless Ûammable gas, CH 3 NH 2 ; m.p. –93.5°C; b.p.
–6.3°C. It can be made by a catalytic
reaction between methanol and ammonia and is used in the manufacture of other organic chemicals.
methylated spirits A mixture
consisting mainly of ethanol with
added methanol (∼9.5%), pyridine
(∼0.5%), and blue dye. The additives
are included to make the ethanol undrinkable so that it can be sold without excise duty for use as a solvent
and a fuel (for small spirit stoves).
methylation A chemical reaction
in which a methyl group (CH 3 –) is introduced in a molecule. A particular
example is the replacement of a hydrogen atom by a methyl group, as in
a *Friedel–Crafts reaction.
methylbenzene (toluene) A
colourless liquid, CH 3 C 6 H 5 ; r.d. 0.9;
m.p. –95°C; b.p. 111°C. Methylbenzene is derived from benzene by replacement of a hydrogen atom by a
methyl group. It can be obtained
from coal tar or made from methylcyclohexane (extracted from crude
oil) by catalytic dehydrogenation. Its
main uses are as a solvent and as a
raw material for producing TNT.
methyl bromide See bromomethane.
2-methylbuta-1,3-diene See isoprene.
methyl chloride See
chloromethane.
methyl cyanide See ethanenitrile.
methylene The highly reactive
*carbene, :CH 2 . The divalent CH 2
group in a compound is the methylene group.
methylene chloride See
dichloromethane.
methanation
352
m
www.AzShimi.ir www.AzShimi.com