ether and thio-ether
TRANSCRIPT
CHARACTERISTICS:Ethers are a class of organic compounds that contain an ether group —
an oxygen atom connected to two alkyl or aryl groups — of
general formula R–O–R'. A typical example is
the solvent and anesthetic diethyl ether, commonly referred to
simply as "ether" (CH3-CH2-O-CH2-CH3). Ethers are common in
organic chemistry and pervasive in biochemistry, as they are
common linkages in carbohydrates and lignin.
THIO-ETHER
Is a functional group in organosulfur chemistry with the
connectivity C-S-C . Like many other sulfur-containing
compounds, volatile thioethers have foul odors. A thioether
is similar to an ether except that it contains a sulfur atom in
place of the oxygen. The grouping of oxygen and sulfur in
the periodic table suggests that the chemical properties of
ethers and thioethers are somewhat similar.
USES OF ETHEREther itself is one of the most important organic solvents and is
widely used in the laboratory as a solvent for fats, oils, resins,
and alkaloids. A mixture of ether vapor with air is violently
explosive; moreover, on long standing, ether may be partly
oxidized to an explosive peroxide compound. Ether must
therefore be stored and used with great care. Its principal uses
are as a solvent, as a starting material for manufacture of
chemical products, and as an anesthetic.
Early Operation with Ether American dentist William Morton
pioneered the use of ether as an
anesthetic in 1846. He used it first
to extract a tooth and then, in an
operation illustrated here, to
remove a tumor from a patient's
neck. The discovery of anesthesia
removed one of the major
obstacles to the progression of
surgery.
USES OF THIO-ETHERThioethers are important in biology, notably in the amino
acid methionine and the cofactor biotin. Petroleum contains
many organosulfur compounds, including thioethers.
Polyphenylene sulfide is a useful high temperature
plastic. Coenzyme M, CH3SCH2CH2SO3-, is the precursor
to methane (i.e. natural gas) via the process
of methanogenesis.
NOMENCLATURE OF ETHER
In the IUPAC nomenclature system, ethers are named using the general
formula "alkoxyalkane", for example CH3-CH2-O-CH3 is methoxyethane. If
the ether is part of a more complex molecule, it is described as an
alkoxy substituent, so -OCH3 would be considered a "methoxy-" group.
The simpler alkyl radical is written in front, so CH3-O-CH2CH3would be
given as methoxy(CH3O)ethane(CH2CH3).
TRIVIAL NAME
IUPAC rules are often not followed for simple ethers. The trivial names for
simple ethers (i.e. those with none or few other functional groups) are a
composite of the two substituents followed by "ether." For example, ethyl
methyl ether (CH3OC2H5), diphenylether (C6H5OC6H5). As for other organic
compounds, very common ethers acquired names before rules for
nomenclature were formalized. Diethyl ether is simply called "ether," but was
once called sweet oil of vitriol. Methyl phenyl ether is anisole, because it was
originally found in aniseed. The aromatic ethers include furans. Acetals (α-
alkoxy ethers R-CH(-OR)-O-R) are another class of ethers with characteristic
properties.
POLYETHERSPolyethers are compounds with more than one ether group.
The crown ethers are examples of low-molecular weight polyethers. Some
toxins produced by dinoflagellates such as brevetoxin and ciguatoxin are in a
class known as cyclic or ladder polyethers.
Polyether generally refers to polymers which contain the ether functional group
in their main chain. The term glycol is reserved for low to medium range molar
mass polymer when the nature of the end-group, which is usually
a hydroxyl group, still matters. The term "oxide" or other terms are used for high
molar mass polymer when end-groups no longer affect polymer properties.
AROMATIC POLYETHERS
The phenyl ether polymers are a class of
polyethers containing aromatic cycles in
their main chain: Polyphenyl ether (PPE)
and Poly(p-phenylen oxide) (PPO).
NOMENCLATURE OF THIO-ETHERS Thioethers are sometimes called sulfides, especially in the older
literature and this term remains in use for the names of specific
thioethers. The two organic substituents are indicated by the
prefixes. (CH3)2S is called dimethylsulfide. Some thioethers are
named by modifying the common name for the corresponding
ether. For example, C6H5SCH3 is methyl phenyl sulfide, but is more
commonly called thioanisole, since its structure is related to that
for anisole, C6H5OCH3.