Information AboutEther |
| CATEGORIES ABOUT ETHER | |
| ethers | |
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Ether is the general name for a class of Chemical Compound s which contain an ether Group — an Oxygen Atom connected to two (substituted) Alkyl groups. A typical example is the Solvent and Anesthetic Diethyl Ether , commonly referred to simply as "ether", (ethoxyethane, CH3-CH2-O-CH2-CH3). PHYSICAL PROPERTIES Ether molecules cannot form Hydrogen Bond s among each other, resulting in a relatively low Boiling Point comparable to that of the analogous Alkane s. Ethers are more Hydrophobic than esters or Amide s of comparable structure. Ethers can act as s. NOMENCLATURE 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 nomenclature of describing the two alkyl groups and appending ''"ether"'', e.g. ''"ethyl methyl ether"'' in the example above, is a Trivial Usage . SIMILAR STRUCTURES Ethers are not to be confused with the following classes of compounds with the same general structure R-O-R.
PRIMARY, SECONDARY, AND TERTIARY ETHERS The terms ''"primary ether"'', ''"secondary ether"'', and ''"tertiary ether"'' are occasionally used and refer to the carbon atom next to the ether oxygen. In a ''primary ether'' this carbon is connected to only one other carbon as in Diethyl Ether CH3-CH2-O-CH2-CH3. An example of a ''secondary ether'' is Diisopropyl Ether (CH3)2CH-O-CH(CH3)2 and that of a ''tertiary ether'' is Di-tert-butyl Ether (CH3)3C-O-C(CH3)3. Dimethyl ether, a ''primary'', a ''secondary'', and a ''tertiary ether''. POLYETHERS Polyethers are compounds with more than one ether group. While the term generally refers to Polymer s like Polyethylene Glycol and Polypropylene Glycol , low molecular compounds such as the Crown Ether s may sometimes be included. ORGANIC REACTIONS Synthesis Ethers can be prepared in the laboratory in several ways.
: R-OH + R-OH → R-O-R + H2O : This direct reaction requires drastic conditions (heat and an acid catalyst) and is usually not applicable. Such conditions can destroy the delicate structures of some Functional Group s. There exist several milder methods to produce ethers.
: R-O- + R-X → R-O-R + X- : This reaction is called the Williamson Ether Synthesis . It involves treatment of a parent Alcohol with a strong Base to form the alkoxide Anion followed by addition of an appropriate aliphatic compound bearing a suitable Leaving Group (R-X). Suitable leaving groups (X) include Iodide , Bromide , or Sulfonate s. This method does not work if R is aromatic like in Bromobenzene . Likewise, this method only gives the best yields for primary carbons, as secondary carbons will undergo E2 elimination on exposure to the basic alkoxide anion used in the reaction. Aryl ethers can be prepared in the Ullmann Condensation .
: R2C=CR2 + R-OH → R2CH-C(-O-R)-R2 : Acid Catalysis is required for this reaction. Tetrahydropyranyl Ether s are used as Protective Group s for alcohols. Cyclic ethers known as Epoxide s can be prepared:
Reactions Ethers in general are of very low chemical Reactivity . Organic reactions are:
: Ethers are Hydrolyzed only under drastic conditions like heating with Boron Tribromide or boiling in Hydrobromic Acid . Lower mineral acids containing a halogen, such as Hydrochloric Acid will cleave ethers, but very slowly. Hydrobromic acid and Hydroiodic Acid are the only two that do so at an appreciable rate. Certain aryl ethers can be cleaved by Aluminium Chloride . : Epoxide s, or cyclic ethers in three-membered rings, are highly susceptible to nucleophilic attack and are reactive in this fashion.
: Primary and secondary ethers with a CH group next to the ether oxygen easily form highly Explosive Organic Peroxide s (e.g. Diethyl Ether Peroxide ) in the presence of oxygen, light, and metal and Aldehyde impurities. For this reason ethers like diethyl ether and THF are usually avoided as Solvent s in industrial processes. IMPORTANT ETHERS
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