catalyst at 200°C and 55 atm. The
compound is used extensively in the
rubber industry and in the manufacture of drugs and dyes.
phenylammonium ion The ion
C 6 H 5 NH 3
+ , derived from *phenylamine.
N-phenylethanamide See acetanilide.
phenylenediamine See diaminobenzene.
phenylethene (styrene) A liquid
hydrocarbon, C 6 H 5 CH:CH 2 ; r.d. 0.9;
m.p. –31°C; b.p. 145°C. It can be
made by dehydrogenating ethylbenzene and is used in making polystyrene.
phenyl group The organic group
C 6 H 5 –, present in benzene.
phenylhydrazine A toxic colourless dense liquid, C 6 H 5 NHNH 2 , b.p.
240°C, which turns brown on exposure to air. It is a powerful reducing
agent, made from *diazonium salts
of benzene. It is used to identify aldehydes and ketones, with which it
forms condensation products called
*hydrazones. With glucose and similar sugars it forms osazones. For
such tests, the nitro derivative 2,4dinitrophenylhydrazine (DNP) is
often preferred as this generally
forms crystalline derivatives that can
be identiÜed by their melting points.
Phenylhydrazine is also used to make
dyes and derivatives of *indole.
phenylhydrazones See hydrazones.
phenylmethanol (benzyl alcohol) A liquid aromatic alcohol,
C 6 H 5 CH 2 OH; r.d. 1.04; m.p. –15.3°C;
b.p. 205.4°C. It is used mainly as a
solvent.
phenylmethylamine See benzylamine.
phenyl methyl ketone (acetophenone) A colourless, crystalline
ketone with an odour of bitter almonds, C 6 H 5 COCH 3 , m.p. 20°C. It is
made by treating benzene with
ethanoyl chloride in the presence of
aluminium chloride. It is used as a
solvent and in making perfumes.
3-phenylpropenoic acid See cinnamic acid.
Phillips process A process for
making high-density polyethene by
polymerizing ethene at high pressure
(30 atmospheres) and 150°C. The
catalyst is chromium(III) oxide supported on silica and alumina.
phlogiston theory A former
theory of combustion in which all
Ûammable objects were supposed
to contain a substance called phlogiston, which was released when the
object burned. The existence of this
hypothetical substance was proposed
in 1669 by Johann Becher, who called
it ‘combustible earth’ (terra pinguis:
literally ‘fat earth’). For example, according to Becher, the conversion of
wood to ashes by burning was explained on the assumption that the
original wood consisted of ash and
terra pinguis, which was released on
burning. In the early 18th century
Georg Stahl renamed the substance
phlogiston (from the Greek for
‘burned’) and extended the theory to
include the calcination (and corrosion) of metals. Thus, metals were
thought to be composed of calx (a
powdery residue) and phlogiston;
when a metal was heated, phlogiston
was set free and the calx remained.
The process could be reversed by
heating the metal over charcoal (a
substance believed to be rich in phlogiston, because combustion almost
totally consumed it). The calx would
absorb the phlogiston released by the
burning charcoal and become metallic again.
409
phlogiston theory
p
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compound is used extensively in the
rubber industry and in the manufacture of drugs and dyes.
phenylammonium ion The ion
C 6 H 5 NH 3
+ , derived from *phenylamine.
N-phenylethanamide See acetanilide.
phenylenediamine See diaminobenzene.
phenylethene (styrene) A liquid
hydrocarbon, C 6 H 5 CH:CH 2 ; r.d. 0.9;
m.p. –31°C; b.p. 145°C. It can be
made by dehydrogenating ethylbenzene and is used in making polystyrene.
phenyl group The organic group
C 6 H 5 –, present in benzene.
phenylhydrazine A toxic colourless dense liquid, C 6 H 5 NHNH 2 , b.p.
240°C, which turns brown on exposure to air. It is a powerful reducing
agent, made from *diazonium salts
of benzene. It is used to identify aldehydes and ketones, with which it
forms condensation products called
*hydrazones. With glucose and similar sugars it forms osazones. For
such tests, the nitro derivative 2,4dinitrophenylhydrazine (DNP) is
often preferred as this generally
forms crystalline derivatives that can
be identiÜed by their melting points.
Phenylhydrazine is also used to make
dyes and derivatives of *indole.
phenylhydrazones See hydrazones.
phenylmethanol (benzyl alcohol) A liquid aromatic alcohol,
C 6 H 5 CH 2 OH; r.d. 1.04; m.p. –15.3°C;
b.p. 205.4°C. It is used mainly as a
solvent.
phenylmethylamine See benzylamine.
phenyl methyl ketone (acetophenone) A colourless, crystalline
ketone with an odour of bitter almonds, C 6 H 5 COCH 3 , m.p. 20°C. It is
made by treating benzene with
ethanoyl chloride in the presence of
aluminium chloride. It is used as a
solvent and in making perfumes.
3-phenylpropenoic acid See cinnamic acid.
Phillips process A process for
making high-density polyethene by
polymerizing ethene at high pressure
(30 atmospheres) and 150°C. The
catalyst is chromium(III) oxide supported on silica and alumina.
phlogiston theory A former
theory of combustion in which all
Ûammable objects were supposed
to contain a substance called phlogiston, which was released when the
object burned. The existence of this
hypothetical substance was proposed
in 1669 by Johann Becher, who called
it ‘combustible earth’ (terra pinguis:
literally ‘fat earth’). For example, according to Becher, the conversion of
wood to ashes by burning was explained on the assumption that the
original wood consisted of ash and
terra pinguis, which was released on
burning. In the early 18th century
Georg Stahl renamed the substance
phlogiston (from the Greek for
‘burned’) and extended the theory to
include the calcination (and corrosion) of metals. Thus, metals were
thought to be composed of calx (a
powdery residue) and phlogiston;
when a metal was heated, phlogiston
was set free and the calx remained.
The process could be reversed by
heating the metal over charcoal (a
substance believed to be rich in phlogiston, because combustion almost
totally consumed it). The calx would
absorb the phlogiston released by the
burning charcoal and become metallic again.
409
phlogiston theory
p
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