trophilic substitution; nucleophilic substitution.
substrate 1. The substance that is
affected by the action of a catalyst;
for example, the substance upon
which an *enzyme acts in a biochemical reaction. 2. The substance on
which some other substance is adsorbed or in which it is absorbed. Examples include the material to which
a dye is attached, the porous solid absorbing a gas, and the *matrix trapping isolated atoms, radicals, etc.
succinic acid See butanedioic acid.
sucrose (cane sugar; beet sugar; saccharose) A sugar comprising one
molecule of glucose linked to a fructose molecule. It occurs widely in
plants and is particularly abundant in
sugar cane and sugar beet (15–20%),
from which it is extracted and
reÜned for table sugar. If heated to
200°C, sucrose becomes caramel.
sugar (saccharide) Any of a group of
water-soluble *carbohydrates of relatively low molecular weight and typically having a sweet taste. The simple
sugars are called *monosaccharides.
More complex sugars comprise between two and ten monosaccharides
linked together: *disaccharides contain two, trisaccharides three, and so
on. The name is often used to refer
speciÜcally to *sucrose (table sugar).
A
• Information about IUPAC nomenclature
sugar of lead See lead(ii)
ethanoate.
sulpha drugs See sulphonamides.
sulphamic acid A colourless crystalline solid, NH 2 SO 2 OH, which is extremely soluble in water and
normally exists as the *zwitterion
H 3 N
+ .SO 3
–
. It is a strong acid, readily
forming sulphamate salts. It is used
in electroplating, hard-water scale removers, herbicides, and artiÜcial
sweeteners.
sulphanes Compounds of hydrogen and sulphur containing chains
of sulphur atoms. They have the
general formula H 2 S n . The simplest
is hydrogen sulphide, H 2 S; other
members of the series are H 2 S 2 ,
H 2 S 3 , H 2 S 4 , etc. See sulphides.
A
• Information about IUPAC nomenclature
sulphanilic acid (4-aminobenzene
sulphonic acid) A colourless crystalline solid, H 2 NC 6 H 4 SO 2 OH, made
by prolonged heating of *phenylamine (aniline) sulphate. It readily
forms *diazo compounds and is used
to make dyes and sulpha drugs.
sulphate A salt or ester of sulphuric(VI) acid. Organic sulphates
have the formula R 2 SO 4 , where R is
an organic group. Sulphate salts contain the ion SO 4
2– .
sulphides 1. Inorganic compounds
of sulphur with more electropositive
elements. Compounds of sulphur
with nonmetals are covalent compounds, e.g. hydrogen sulphide (H 2 S).
Metals form ionic sulphides containing the S
2– ion; these are salts of hydrogen sulphide. Polysulphides can
also be produced containing the polymeric ion S x
2–
. 2. (or thio ethers) Organic compounds that contain the
group –S– linked to two hydrocarbon
groups. Organic sulphides are named
from the linking groups, e.g. dimethyl sulphide (CH 3 SCH 3 ), ethyl
methyl sulphide (C 2 H 5 SCH 3 ). They
are analogues of ethers in which the
oxygen is replaced by sulphur (hence
the alternative name) but are generally more reactive than ethers. Thus
they react with halogen compounds
to form *sulphonium compounds
and can be oxidized to *sulphoxides.
sulphinate (dithionite; hyposulsubstrate
508
s
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substrate 1. The substance that is
affected by the action of a catalyst;
for example, the substance upon
which an *enzyme acts in a biochemical reaction. 2. The substance on
which some other substance is adsorbed or in which it is absorbed. Examples include the material to which
a dye is attached, the porous solid absorbing a gas, and the *matrix trapping isolated atoms, radicals, etc.
succinic acid See butanedioic acid.
sucrose (cane sugar; beet sugar; saccharose) A sugar comprising one
molecule of glucose linked to a fructose molecule. It occurs widely in
plants and is particularly abundant in
sugar cane and sugar beet (15–20%),
from which it is extracted and
reÜned for table sugar. If heated to
200°C, sucrose becomes caramel.
sugar (saccharide) Any of a group of
water-soluble *carbohydrates of relatively low molecular weight and typically having a sweet taste. The simple
sugars are called *monosaccharides.
More complex sugars comprise between two and ten monosaccharides
linked together: *disaccharides contain two, trisaccharides three, and so
on. The name is often used to refer
speciÜcally to *sucrose (table sugar).
A
• Information about IUPAC nomenclature
sugar of lead See lead(ii)
ethanoate.
sulpha drugs See sulphonamides.
sulphamic acid A colourless crystalline solid, NH 2 SO 2 OH, which is extremely soluble in water and
normally exists as the *zwitterion
H 3 N
+ .SO 3
–
. It is a strong acid, readily
forming sulphamate salts. It is used
in electroplating, hard-water scale removers, herbicides, and artiÜcial
sweeteners.
sulphanes Compounds of hydrogen and sulphur containing chains
of sulphur atoms. They have the
general formula H 2 S n . The simplest
is hydrogen sulphide, H 2 S; other
members of the series are H 2 S 2 ,
H 2 S 3 , H 2 S 4 , etc. See sulphides.
A
• Information about IUPAC nomenclature
sulphanilic acid (4-aminobenzene
sulphonic acid) A colourless crystalline solid, H 2 NC 6 H 4 SO 2 OH, made
by prolonged heating of *phenylamine (aniline) sulphate. It readily
forms *diazo compounds and is used
to make dyes and sulpha drugs.
sulphate A salt or ester of sulphuric(VI) acid. Organic sulphates
have the formula R 2 SO 4 , where R is
an organic group. Sulphate salts contain the ion SO 4
2– .
sulphides 1. Inorganic compounds
of sulphur with more electropositive
elements. Compounds of sulphur
with nonmetals are covalent compounds, e.g. hydrogen sulphide (H 2 S).
Metals form ionic sulphides containing the S
2– ion; these are salts of hydrogen sulphide. Polysulphides can
also be produced containing the polymeric ion S x
2–
. 2. (or thio ethers) Organic compounds that contain the
group –S– linked to two hydrocarbon
groups. Organic sulphides are named
from the linking groups, e.g. dimethyl sulphide (CH 3 SCH 3 ), ethyl
methyl sulphide (C 2 H 5 SCH 3 ). They
are analogues of ethers in which the
oxygen is replaced by sulphur (hence
the alternative name) but are generally more reactive than ethers. Thus
they react with halogen compounds
to form *sulphonium compounds
and can be oxidized to *sulphoxides.
sulphinate (dithionite; hyposulsubstrate
508
s
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