ore is smelted in this way so that the
metal melts and, being denser than
the molten *slag, sinks below the
slag, enabling it to be removed from
the furnace separately.
SMILES SimpliÜed molecular input
line entry system. A type of line notation for representing molecules and
reactions. It uses standard atom symbols but hydrogen atoms are omitted.
A double bond is represented by an
equals sign and a triple bond by a
hash sign. So ethane is CC, ethene is
C=C, and ethyne is C#C.
Branched structures are given
using brackets. For example, triethylamine ((C 2 H 5 ) 3 N) is represented by
CCN(CC)CC; ethanoic (acetic acid)
(CH3COOC) is CC(=O)O. Ring structures use numbers to show connections. For instance, cyclohexane is
C1CCCCC1, where the C1 atoms are
the ones joined to form the ring.
SMILES notation for aromatic molecules uses lower case letters. Benzene is c1ccccc1; chlorobenzene
could be c1c(Cl)cccc1. Rules exist for
expressing isotope and stereochemistry information and there is a notation for reactions. Rules also exist for
choosing a unique SMILES, which is a
deÜnitive representation of the many
possible valid strings that may be
written for a given compound. An
extension of SMILES to describe molecular patterns (for substructure
searches) is called SMARTS.
A
• A SMILES tutorial produced by Daylight
Chemical Information Systems Inc.
smoke A Üne suspension of solid
particles in a gas.
S N 1 reaction See nucleophilic substitution.
S N 2 reaction See nucleophilic substitution.
SNG Substitute (or synthetic) natural gas; a mixture of gaseous hydrocarbons produced from coal, petroleum, etc., and suitable for use as a
fuel. Before the discovery of natural
gas *coal gas was widely used as a domestic and industrial fuel. This gave
way to natural gas in the early part
of this century in the US and other
countries where natural gas was
plentiful. The replacement of coal
gas occurred somewhat later in the
UK and other parts of Europe. More
recently, interest has developed in
ways of manufacturing hydrocarbon
gas fuels. The main sources are coal
and the naphtha fraction of petroleum. In the case of coal three methods have been used: (1) pyrolysis – i.e.
more efÜcient forms of destructive
distillation, often with further hydrogenation of the hydrocarbon products; (2) heating the coal with
hydrogen and catalysts to give hydrocarbons – a process known as
hydroliquefaction (see also bergius
process); (3) producing carbon
monoxide and hydrogen and obtaining hydrocarbons by the *Fischer–
Tropsch process. SNG from naptha is
made by steam *reforming. See crg
process.
soap A substance made by boiling
animal fats with sodium hydroxide.
The reaction involves the hydrolysis
of *glyceride esters of fatty acids to
glycerol and sodium salts of the acids
present (mainly the stearate, oleate,
and palmitate), giving a soft semisolid with *detergent action. Potassium hydroxide gives a more liquid
product (soft soap). By extension,
other metal salts of long-chain fatty
acids are also called soaps. See also
saponification.
soda Any of a number of sodium
compounds, such as caustic soda
(NaOH) or, especially, washing soda
(Na 2 CO 3 .10H 2 O).
SMILES
486
s
www.AzShimi.ir www.AzShimi.com
metal melts and, being denser than
the molten *slag, sinks below the
slag, enabling it to be removed from
the furnace separately.
SMILES SimpliÜed molecular input
line entry system. A type of line notation for representing molecules and
reactions. It uses standard atom symbols but hydrogen atoms are omitted.
A double bond is represented by an
equals sign and a triple bond by a
hash sign. So ethane is CC, ethene is
C=C, and ethyne is C#C.
Branched structures are given
using brackets. For example, triethylamine ((C 2 H 5 ) 3 N) is represented by
CCN(CC)CC; ethanoic (acetic acid)
(CH3COOC) is CC(=O)O. Ring structures use numbers to show connections. For instance, cyclohexane is
C1CCCCC1, where the C1 atoms are
the ones joined to form the ring.
SMILES notation for aromatic molecules uses lower case letters. Benzene is c1ccccc1; chlorobenzene
could be c1c(Cl)cccc1. Rules exist for
expressing isotope and stereochemistry information and there is a notation for reactions. Rules also exist for
choosing a unique SMILES, which is a
deÜnitive representation of the many
possible valid strings that may be
written for a given compound. An
extension of SMILES to describe molecular patterns (for substructure
searches) is called SMARTS.
A
• A SMILES tutorial produced by Daylight
Chemical Information Systems Inc.
smoke A Üne suspension of solid
particles in a gas.
S N 1 reaction See nucleophilic substitution.
S N 2 reaction See nucleophilic substitution.
SNG Substitute (or synthetic) natural gas; a mixture of gaseous hydrocarbons produced from coal, petroleum, etc., and suitable for use as a
fuel. Before the discovery of natural
gas *coal gas was widely used as a domestic and industrial fuel. This gave
way to natural gas in the early part
of this century in the US and other
countries where natural gas was
plentiful. The replacement of coal
gas occurred somewhat later in the
UK and other parts of Europe. More
recently, interest has developed in
ways of manufacturing hydrocarbon
gas fuels. The main sources are coal
and the naphtha fraction of petroleum. In the case of coal three methods have been used: (1) pyrolysis – i.e.
more efÜcient forms of destructive
distillation, often with further hydrogenation of the hydrocarbon products; (2) heating the coal with
hydrogen and catalysts to give hydrocarbons – a process known as
hydroliquefaction (see also bergius
process); (3) producing carbon
monoxide and hydrogen and obtaining hydrocarbons by the *Fischer–
Tropsch process. SNG from naptha is
made by steam *reforming. See crg
process.
soap A substance made by boiling
animal fats with sodium hydroxide.
The reaction involves the hydrolysis
of *glyceride esters of fatty acids to
glycerol and sodium salts of the acids
present (mainly the stearate, oleate,
and palmitate), giving a soft semisolid with *detergent action. Potassium hydroxide gives a more liquid
product (soft soap). By extension,
other metal salts of long-chain fatty
acids are also called soaps. See also
saponification.
soda Any of a number of sodium
compounds, such as caustic soda
(NaOH) or, especially, washing soda
(Na 2 CO 3 .10H 2 O).
SMILES
486
s
www.AzShimi.ir www.AzShimi.com