ether
Top
(ē'thər) 
n.
n.
- Any of a class of organic compounds in which two hydrocarbon groups are linked by an oxygen atom.
- A volatile, highly flammable liquid, C2H5OC2H5, derived from the distillation of ethyl alcohol with sulfuric acid and used as a reagent and solvent. It was formerly used as an anesthetic. Also called diethyl ether, ethyl ether.
- The regions of space beyond the earth's atmosphere; the heavens.
- The element believed in ancient and medieval civilizations to fill all space above the sphere of the moon and to compose the stars and planets.
- Physics. An all-pervading, infinitely elastic, massless medium formerly postulated as the medium of propagation of electromagnetic waves.
[Middle English, upper air, from Latin aethēr, from Greek aithēr.]
etheric e·ther'ic (ĭ-thĕr'ĭk, ĭ-thîr'-) adj.
Top
Any of a class of organic compounds whose molecular structure has an oxygen atom interposed between two carbon atoms that are part of hydrocarbon molecules. Ethers have the general chemical formula ROR, in which R and R represent the hydrocarbons. They resemble alcohols but generally are less dense, less soluble in water, more volatile, and more inert. They are used in chemical processing, for extraction and separation of chemicals, and as solvents. Some are used as insecticides and soil fumigants. They are also used in medicine and pharmacology. Codeine is the methyl ether of morphine. The term ether often refers to ethyl ether (C2H5OC2H5), best known as an anesthetic but also used as a solvent, an extractant, and a reaction medium.
For more information on ether, visit Britannica.com.
Top
(1) An invisible medium through which all light, heat and electromagnetic waves propagate. Pronounced "ee-ther" with the "th" as in the word "thought," ether was postulated from the 1600s to the 1800s. The word inspired the name Ethernet.
(2) A group of chemical compounds, the most popular of which is the colorless and transparent diethyl ether, used as a solvent and anesthetic. Diethyl ether was synthesized in the 1500s and named "ether" in the 1700s.
Download Computer Desktop Encyclopedia to your PC, iPhone or Android.
Houghton Mifflin Guide to Science & Technology:
Top
Does the ether exist?
In 1881 Albert A. Michelson and Edward Morley tried to measure the absolute velocity of Earth with respect to the rest of the universe. The result of their measurement showed that Earth is at rest in space, but no one believed that that could be true. The idea of a motionless Earth had been given up 300 years earlier. Something had to be wrong with the experiment.
The problem at first glance seemed to be with light. Ever since Thomas Young had demonstrated in 1803 that light produces interference patterns, it was assumed that light must be waves, a view previously held by Christiaan Huygens and others. All those who espoused the wave theory--the alternative theory was that light consisted of particles--assumed that light must be waves in something. When Augustin-Jean Fresnel began to work on the wave theory of light, he named the something ether, after Aristotle's fifth element. Fresnel was able to show that light waves are more like water waves (but in three dimensions instead of just up and down) than they are like sound waves (which are back and forth instead of up and down).
Michelson had taken a suggestion of James Clerk Maxwell, made in 1875, to develop a sensitive measuring tool based on the interference patterns of waves of light. The Michelson-Morley experiment was designed to use the interferometer, Michelson's new tool, to measure how Earth moves through the ether, which was assumed to be stationary. Michelson and Morley measured the speed of light in two perpendicular directions. The speed was found to be the same, implying that Earth stands still.
Others had different explanations. Both George Francis Fitzgerald and Hendrik Antoon Lorentz suggested that the problem could be resolved by assuming that objects contract when they move. By assigning the correct value to the contraction, the speed of light could be made to appear the same in two different directions, since the apparatus used to measure it would contract in the direction in which Earth is moving.
In 1905 Albert Einstein resolved the issue in a different way. Einstein perceived that the same physical laws must be true in all frames of reference in steady motion with respect to each other. But this requirement also means that light must have the same speed no matter how a body is moving. There can be no fixed frame of reference against which Earth moves, so Michelson and Morley got the correct result. In addition, the Fitzgerald-Lorentz contraction is a real effect, explained by Einstein's theory. Furthermore, in a separate paper, Einstein showed that light behaves like a particle as well as like a wave. Although this wave-particle duality remains difficult to picture, it has become quite clear since 1905 that light has both wave and particle properties. A particle does not require a medium the way that a wave does.
Does the ether exist? Einstein's theory of special relativity suggests that the question is irrelevant. Certainly no one thinks today that a solid medium pervades space. On the other hand, it is widely believed that there is no real vacuum. Arno Penzias and Robert Wilson detected in 1964 the cosmic background radiation, a leftover of the big bang. This radiation is pervasive and basically the same in all directions. It is possible to measure Earth's movement against this background radiation. As it turns out, Earth moves.
Top
A city which fell to the lot of the tribe of Judah (Josh 15:20, 42) when the land of Canaan was divided by Joshua among the Children of Israel (Josh 14:1); however it is also mentioned as being in the domain of Simeon (Josh 19:7). It has been suggested that these are two different cities but many scholars disagree. It was in the eastern lowlands of Judah but its present location is unknown.
Concordance
Josh 15:42; 19:7
Columbia Encyclopedia:
Top
Ether
in chemistry
in physics and astronomy
in physics and astronomy
ether, any of a number of organic compounds whose molecules contain two hydrocarbon groups joined by single bonds to an oxygen atom. The most common of these compounds is ethyl ether, CH3CH2OCH2CH3, often called simply ether, a colorless, volatile liquid with a distinctive odor; its IUPAC name is ethoxyethane. Ethyl ether boils at 34.5°C and is extremely flammable. It is insoluble in water but mixes with many organic solvents and is widely used as a solvent itself, e.g., for fats and oils. Its most familiar historical application is as an anesthetic. An ether such as ethyl ether in which both hydrocarbon groups are identical is said to be a simple, or symmetrical, ether. An ether in which the two groups differ (e.g., methyl ethyl ether, CH3OCH2CH3) is said to be a mixed, or unsymmetrical, ether. Ethers are often prepared commercially by heating an alcohol with sulfuric acid; the reaction is one of dehydration. In the laboratory ethers are often prepared by reaction of an alkyl halide with a sodium alkoxide (a method called the Williamson synthesis). Ethers are usually chemically unreactive but can be cleaved (broken apart) at high temperatures by concentrated hydrogen halides; initially an alkyl halide and an alcohol are formed. Epoxides are a special class of cyclic ethers.
ether or aether, in physics and astronomy, a hypothetical medium for transmitting light and heat (radiation), filling all unoccupied space; it is also called luminiferous ether. In Newtonian physics all waves are propagated through a medium, e.g., water waves through water, sound waves through air. When James Clerk Maxwell developed his electromagnetic theory of light, Newtonian physicists postulated ether as the medium that transmitted electromagnetic waves. Ether was held to be invisible, without odor, and of such a nature that it did not interfere with the motions of bodies through space. The concept was intended to connect the Newtonian mechanistic wave theory with Maxwell's field theory. However, all attempts to demonstrate its existence, most notably the Michelson-Morley experiment of 1887, produced negative results and stimulated a vigorous debate among physicists that was not ended until the special theory of relativity, proposed by Albert Einstein in 1905, became accepted. The theory of relativity eliminated the need for a light-transmitting medium, so that today the term ether is used only in a historical context.
Word Tutor:
Top
ether
IN BRIEF: n. - A colorless volatile highly inflammable liquid formerly used as an inhalation anesthetic; A medium that was once supposed to fill all space and to support the propagation of electromagnetic waves.
Tutor's tip: The doctor told her patient she could have "either" (one of two) no anesthetic or "ether" (a chemical) .
LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!
Wiley Dictionary of Flavors:
Top
Ethers
As a compound class, ethers are fairly variable in flavor type. Diphenyl is a rosy character, beta naphthyl ethyl ether is sweet, aromatic, and grapey. Tetrahydropyrans are six-membered oxygen-containing heterocyclic rings. Dioxanes are six-membered heterocycles with two oxygens para to each other. Structures like pyrazines are their nitrogen-containing counterpart. Oenanthic ether is not really an ether but is a complex mixture of esters and other trace compounds.
Top
- any anhydride, of general formula R1 — O — R2, formed between two (identical or nonidentical) organic hydroxy compounds.
- the common name for diethyl ether (or ethyl ether or ethoxyethane), C2H5 — O — C2H5.
| ethanolysed cellulose, ethanolic, ethanolaminephosphotransferase | |
| ether lipid, ethereal, ethereal sulfate |
Top
1. diethyl ether: a colorless, transparent, very volatile, highly inflammable liquid with a characteristic odor; given by inhalation to produce general anesthesia.
2. any organic compound containing an oxygen atom bonded to two carbon atoms.
- spiritus e. nit. — used as a stimulant for depressed animals, both as an inhalant and in oral drenches.
- vinyl e. — a clear colorless liquid used as an inhalation anesthetic.
Random House Word Menu:
Top
categories related to 'ether'
- Tools and Techniques - ether: volatile, flammable liquid used as solvent and, formerly, as anesthetic
- Branches, Laws, Theories, and Techniques - ether: quintessence
- PHARMACOLOGY - ether: volatile liquid formerly used as anesthetic by inhalation
- Rites, Practices, Spells, and Symbols - ether: rarefied element; medium in which spirits appear; intoxicating gas
See crossword solutions for the clue
Top
This article is about a general class of organic compounds. For other uses, see Aether.
.png)
Ethers (
/ˈiːθər/) 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'.[1] 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.
|
Contents
|
Structure and bonding
Ethers feature C-O-C linkage defined by a bond angle of about 104.5° and C-O distances of about 140 pm. The barrier to rotation about the C-O bonds is low. The bonding of oxygen in ethers, alcohols, and water is similar. In the language of valence bond theory, the hybridization at oxygen is sp3.
Oxygen is more electronegative than carbon, thus the hydrogens alpha to ethers are more acidic than in simple hydrocarbons. They are far less acidic than hydrogens alpha to carbonyl groups (such as in ketones or aldehydes), however.
- Depending on the groups at R and R', ether is classified into two types:
1) Simple ethers or symmetrical ethers 2) Mixed ethers or asymmetrical ethers
Nomenclature
The names for simple ethers (i.e. those with none or few other functional groups) are a composite of the two substituents followed by "ether." Ethyl methyl ether (CH3OC2H5), diphenylether (C6H5OC6H5). IUPAC rules are often not followed for simple ethers. 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.
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-CH2CH3 would be given as methoxy(CH3O)ethane(CH2CH3). The nomenclature of describing the two alkyl groups and appending "ether", e.g. "ethyl methyl ether" in the example above, is a trivial usage.
Polyethers
Polyethers are compounds with more than one ether group.
The crown ethers are examples of low-molecular 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.
Aliphatic polyethers
| Name of the polymers with low to medium molar mass | Name of the polymers with high molar mass | Preparation | Repeating unit | Examples of trade names |
|---|---|---|---|---|
| Paraformaldehyde | Polyoxymethylene (POM) or polyacetal or polyformaldehyde | Step-growth polymerisation of formaldehyde | -CH2O- | Delrin from DuPont |
| Polyethylene glycol (PEG) | Polyethylene oxide (PEO) or polyoxyethylene (POE) | Ring-opening polymerization of ethylene oxide | -CH2CH2O- | Carbowax from Dow |
| Polypropylene glycol (PPG) | Polypropylene oxide (PPO) ou polyoxypropylene) (POP) | Anionic ring-opening polymerization of propylene oxide | -CH2CH(CH3)O- | |
| Polytetramethylene glycol (PTMG) or Polytetramethylene ether glycol (PTMEG) | Polytetrahydrofuran (PTHF) | Acid-catalyzed ring-opening polymerization of tetrahydrofuran | -CH2CH2CH2CH2O- | Terathane from Invista and PolyTHF from BASF |
Aromatic polyethers
The phenyl ether polymers are a class of polyethers containing aromatic cycles in their main chain: Polyphenyl ether (PPE) and Poly(p-phenylene oxide) (PPO).
Related compounds
Many classes of compounds with C-O-C linkages are not considered ethers: Esters (R-C(=O)-O-R), hemiacetals (R-CH(-OH)-O-R), carboxylic acid anhydrides (RC(=O)-O-C(=O)R).
Physical properties
Ether molecules cannot form hydrogen bonds with each other, resulting in a relatively low boiling points compared to those of the analogous alcohols. The difference, however, in the boiling points of the ethers and their isometric alcohols becomes lower as the carbon chains become longer, as the van der Waals interactions of the extended carbon chain dominates over the presence of hydrogen bonding.
Ethers are slightly polar. The C-O-C bond angle in the functional group is about 110°, and the C-O dipoles do not cancel out. Ethers are more polar than alkenes but not as polar as alcohols, esters, or amides of comparable structure. However, the presence of two lone pairs of electrons on the oxygen atoms makes hydrogen bonding with water molecules possible.
Cyclic ethers such as tetrahydrofuran and 1,4-dioxane are miscible in water because of the more exposed oxygen atom for hydrogen bonding as compared to aliphatic ethers.
| Selected data about some alkyl ethers | |||||
|---|---|---|---|---|---|
| Ether | Structure | m.p. (°C) | b.p. (°C) | Solubility in 1 liter of H2O | Dipole moment (D) |
| Dimethyl ether | CH3-O-CH3 | -138.5 | -23.0 | 70 g | 1,30 |
| Diethyl ether | CH3CH2-O-CH2CH3 | -116.3 | 34.4 | 69 g | 1.14 |
| Tetrahydrofuran | O(CH2)4 | -108.4 | 66.0 | Miscible | 1.74 |
| Dioxane | O(C2H4)2O | 11.8 | 101.3 | Miscible | 0.45 |
Reactions
Structure of the polymeric diethyl ether peroxide
Ethers in general are of low chemical reactivity, but they are more reactive than alkanes (epoxides, ketals, and acetals are unrepresentative classes of ethers and are discussed in separate articles). Important reactions are listed below.[2]
Ether cleavage
Although ethers resist hydrolysis, they are cleaved by mineral acids such as hydrobromic acid and hydroiodic acid. Hydrogen chloride cleaves ethers only slowly. Methyl ethers typically afford methyl halides:
- ROCH3 + HBr → CH3Br + ROH
These reactions proceed via onium intermediates, i.e. [RO(H)CH3]+Br-.
Some ethers rapidly cleave with boron tribromide (even aluminium chloride is used in some cases) to give the alkyl bromide.[3] Depending on the substituents, some ethers can be cleaved with a variety of reagents, e.g. strong base.
Peroxide formation
When stored in the presence of air or oxygen, ethers tend to form explosive peroxides, such as diethyl ether peroxide. The reaction is accelerated by light, metal catalysts, and aldehydes. In addition to avoiding storage conditions likely to form peroxides, it is recommended, when an ether is used as a solvent, not to distill it to dryness, as any peroxides that may have formed, being less volatile than the original ether, will become concentrated in the last few drops of liquid.
Lewis bases
Ethers serve as Lewis bases and Bronsted bases. Strong acids protonate the oxygen to give "onium ions." For instance, diethyl ether forms a complex with boron trifluoride, i.e. diethyl etherate (BF3.OEt2). Ethers also coordinate to Mg(II) center in Grignard reagents. Polyethers, including many antibiotics, cryptands, and crown ethers, bind alkali metal cations strongly.
Alpha-halogenation
This reactivity is akin to the tendency of ethers with alpha hydrogen atoms to form peroxides. Chlorine gives alpha-chloroethers.
Synthesis
Ethers can be prepared in the laboratory in several different ways.
Dehydration of alcohols
The Dehydration of alcohols affords ethers:
- 2 R-OH → R-O-R + H2O at high temperature
This direct reaction requires elevated temperatures (about 125 °C). The reaction is catalyzed by acids, usually sulfuric acid. The method is effective for generating symmetrical ethers, but not unsymmetrical ethers. Diethyl ether is produced from ethanol by this method. Cyclic ethers are readily generated by this approach. Such reactions must compete with dehydration of the alcohol:
- R-CH2-CH2(OH) → R-CH=CH2 + H2O
The dehydration route often requires conditions incompatible with delicate molecules. Several milder methods exist to produce ethers.
Williamson ether synthesis
Nucleophilic displacement of alkyl halides by alkoxides
- R-ONa + R'-X → R-O-R' + NaX
This reaction is called the Williamson ether synthesis. It involves treatment of a parent alcohol with a strong base to form the alkoxide, followed by addition of an appropriate aliphatic compound bearing a suitable leaving group (R-X). Suitable leaving groups (X) include iodide, bromide, or sulfonates. This method usually does not work well for aryl halides (e.g. bromobenzene (see Ullmann condensation below). Likewise, this method only gives the best yields for primary halides. Secondary and tertiary halides are prone to undergo E2 elimination on exposure to the basic alkoxide anion used in the reaction due to steric hindrance from the large alkyl groups.
In a related reaction, alkyl halides undergo nucleophilic displacement by phenoxides. The R-X cannot be used to react with the alcohol. However, phenols can be used to replace the alcohol, while maintaining the alkyl halide. Since phenols are acidic, they readily react with a strong base like sodium hydroxide to form phenoxide ions. The phenoxide ion will then substitute the -X group in the alkyl halide, forming an ether with an aryl group attached to it in a reaction with an SN2 mechanism.
- C6H5OH + OH- → C6H5-O- + H2O
- C6H5-O- + R-X → C6H5OR
Ullmann condensation
The Ullmann condensation is similar to the Williamson method except that the substrate is an aryl halide. Such reactions generally require a catalyst, such as copper.
Electrophilic addition of alcohols to alkenes
Alcohols add to electrophilically activated alkenes.
- R2C=CR2 + R-OH → R2CH-C(-O-R)-R2
Acid catalysis is required for this reaction. Often, mercury trifluoroacetate (Hg(OCOCF3)2) is used as a catalyst for the reaction, geneating an ether with Markovnikov regiochemistry. Using similar reactions, tetrahydropyranyl ethers are used as protective groups for alcohols.
Preparation of epoxides
Main article: epoxide
Epoxides are typically prepared by oxidation of alkenes. The most important epoxide in terms of industrial scale is ethylene oxide, which is produced by oxidation of ethylene with oxygen. Other epoxides are produced by one of two routes:
- By the oxidation of alkenes with a peroxyacid such as m-CPBA.
- By the base intramolecular nucleophilic substitution of a halohydrin.
Important ethers
 |
Ethylene oxide | The smallest cyclic ether. |
 |
Dimethyl ether | An aerosol spray propellant. A potential renewable alternative fuel for diesel engines with a cetane rating as high as 56-57. |
 |
Diethyl ether | A common low boiling solvent (b.p. 34.6 °C), and an early anaesthetic. Used as starting fluid for diesel engines. |
 |
Dimethoxyethane (DME) | A high boiling solvent (b.p. 85 °C): |
 |
Dioxane | A cyclic ether and high boiling solvent (b.p. 101.1 °C). |
 |
Tetrahydrofuran (THF) | A cyclic ether, one of the most polar simple ethers that is used as a solvent. |
 |
Anisole (methoxybenzene) | An aryl ether and a major constituent of the essential oil of anise seed. |
 |
Crown ethers | Cyclic polyethers that are used as phase transfer catalysts. |
 |
Polyethylene glycol (PEG) | A linear polyether, e.g. used in cosmetics and pharmaceuticals. |
References
 |
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2007) |
- ^ Nic, M.; Jirat, J.; Kosata, B., eds. (2006–). "ethers". IUPAC Compendium of Chemical Terminology (Online ed.). doi:10.1351/goldbook.E02221. ISBN 0-9678550-9-8. http://goldbook.iupac.org/E02221.html.
- ^ Wilhelm Heitmann, Günther Strehlke, Dieter Mayer "Ethers, Aliphatic" in Ullmann's Encyclopedia of Industrial Chemistry" Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a10_023
- ^ J. F. W. McOmie and D. E. West (1973), "3,3'-Dihydroxylbiphenyl", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV5P0412; Coll. Vol. 5: 412
External links
- ILPI page about ethers.
- An Account of the Extraordinary Medicinal Fluid, called Aether, by M. Turner, circa 1788, from Project Gutenberg
|
||||||||
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Translations:
Top
Ether
Nederlands (Dutch)
ether, opperste hemelsfeer, stof dat opperste hemelsfeer vult (filosofie)
Français (French)
n. - (Chim, Phys) éther, les éthers, les espaces célestes (littér)
Ελληνική (Greek)
n. - (χημ.) αιθήρ. αιθέρας
Português (Portuguese)
n. - éter (m) (Quím.)
Русский (Russian)
эфир, небесное пространство
中文（简体）(Chinese (Simplified))
乙醚, 以太, 醚, 太空, 苍穹
中文（繁體）(Chinese (Traditional))
n. - 乙醚, 以太, 醚, 太空, 蒼穹
한국어 (Korean)
n. - 하늘, 빛, 열, 전자기의 복사 현상의 가상적 매체
日本語 (Japanese)
n. - エーテル, 天空上層の空間, ラジオ
العربيه (Arabic)
(الاسم) السماء, الأثير
עברית (Hebrew)
n. - אתר, סם הרדמה
If you are unable to view some languages clearly, click here.
Post a question - any question - to the WikiAnswers community:
Copyrights:
American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
Read more
Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
Computer Desktop Encyclopedia
THIS DEFINITION IS FOR PERSONAL USE ONLY.
All other reproduction is strictly prohibited without permission from the publisher.
© 1981-2012 The Computer Language Company Inc. All rights reserved. Read more
All other reproduction is strictly prohibited without permission from the publisher.
© 1981-2012 The Computer Language Company Inc. All rights reserved. Read more
Houghton Mifflin Guide to Science & Technology
History of Science and Technology, edited by Bryan Bunch and Alexander Hellemans. Copyright © 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
Read more
Bible Dictionary and Concordance
Illustrated Dictionary & Concordance of the Bible. Copyright © 1986 by G.G. The Jerusalem Publishing House, Ltd. All rights reserved.
Read more
Columbia Encyclopedia
The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2012, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/.
Read more
Word Tutor
Copyright © 2004-present by eSpindle Learning, a 501(c) nonprofit organization. All rights reserved.
eSpindle provides personalized spelling and vocabulary tutoring online; sign up free. Read more
eSpindle provides personalized spelling and vocabulary tutoring online; sign up free. Read more
Wiley Dictionary of Flavors
Copyright © 2008 by Wiley-Blackwell. Wiley and the Wiley logo are registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and other countries. Used here by license. Read more
Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
Read more
Saunders Veterinary Dictionary
Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.
Read more
Random House Word Menu
© 2010 Write Brothers Inc. Word Menu is a registered trademark of the Estate of Stephen Glazier.
Write Brothers Inc.
All rights reserved.
Read more
Bradford's Crossword Solver's Dictionary
Collins Bradford's Crossword Solver's Dictionary © Anne Bradford, 1986, 1993, 1997, 2000, 2003, 2005, 2008
HarperCollins Publishers
All rights reserved.
Read more
Wikipedia on Answers.com
This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Ether.
Read more
