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Ether and Thio-Ether

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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.

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