Ethers are a class of organic compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula R–O–R′, where R and R′ represent the alkyl or aryl groups. Ethers can again be classified into two varieties: if the alkyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group 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 even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin.
A solvent is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar molecules and the most common solvent used by living things; all the ions and proteins in a cell are dissolved in water within the cell.
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent.
An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They are written as RO−, where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands. Alkoxides, although generally not stable in protic solvents such as water, occur widely as intermediates in various reactions, including the Williamson ether synthesis. Transition metal alkoxides are widely used for coatings and as catalysts.
Charles John Pedersen was an American organic chemist best known for describing methods of synthesizing crown ethers during his entire 42-year career as a chemist for DuPont at DuPont Experimental Station in Wilmington, Delaware and at DuPont's Jackson Laboratory in Deepwater, New Jersey. Often associated with Reed McNeil Izatt, Pedersen also shared the Nobel Prize in Chemistry in 1987 with Donald J. Cram and Jean-Marie Lehn. He is the only Nobel Prize laureate born in Korea other than Peace Prize laureate Kim Dae-jung.
Crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups. The most common crown ethers are cyclic oligomers of ethylene oxide, the repeating unit being ethyleneoxy, i.e., –CH2CH2O–. Important members of this series are the tetramer (n = 4), the pentamer (n = 5), and the hexamer (n = 6). The term "crown" refers to the resemblance between the structure of a crown ether bound to a cation, and a crown sitting on a person's head. The first number in a crown ether's name refers to the number of atoms in the cycle, and the second number refers to the number of those atoms that are oxygen. Crown ethers are much broader than the oligomers of ethylene oxide; an important group are derived from catechol.
Dimethoxyethane, also known as glyme, monoglyme, dimethyl glycol, ethylene glycol dimethyl ether, dimethyl cellosolve, and DME, is a colorless, aprotic, and liquid ether that is used as a solvent, especially in batteries. Dimethoxyethane is miscible with water.
Cryptands are a family of synthetic bicyclic and polycyclic multidentate ligands for a variety of cations. The Nobel Prize for Chemistry in 1987 was given to Donald J. Cram, Jean-Marie Lehn, and Charles J. Pedersen for their efforts in discovering and determining uses of cryptands and crown ethers, thus launching the now flourishing field of supramolecular chemistry. The term cryptand implies that this ligand binds substrates in a crypt, interring the guest as in a burial. These molecules are three-dimensional analogues of crown ethers but are more selective and strong as complexes for the guest ions. The resulting complexes are lipophilic.
Macrocycles are often described as molecules and ions containing a twelve or more membered ring. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry.
In chemistry, a phase-transfer catalyst or PTC is a catalyst that facilitates the migration of a reactant from one phase into another phase where reaction occurs. Phase-transfer catalysis is a special form of heterogeneous catalysis. Ionic reactants are often soluble in an aqueous phase but insoluble in an organic phase in the absence of the phase-transfer catalyst. The catalyst functions like a detergent for solubilizing the salts into the organic phase. Phase-transfer catalysis refers to the acceleration of the reaction upon the addition of the phase-transfer catalyst.
18-Crown-6 is an organic compound with the formula [C2H4O]6 and the IUPAC name of 1,4,7,10,13,16-hexaoxacyclooctadecane. It is a white, hygroscopic crystalline solid with a low melting point. Like other crown ethers, 18-crown-6 functions as a ligand for some metal cations with a particular affinity for potassium cations (binding constant in methanol: 106 M−1). The point group of 18-crown-6 is S6. The dipole moment of 18-crown-6 varies in different solvent and under different temperature. Under 25 °C, the dipole moment of 18-crown-6 is 2.76 ± 0.06 D in cyclohexane and 2.73 ± 0.02 in benzene. The synthesis of the crown ethers led to the awarding of the Nobel Prize in Chemistry to Charles J. Pedersen.
Glycol ethers are a group of solvents based on alkyl ethers of ethylene glycol or propylene glycol commonly used in paints and cleaners. These solvents typically have a higher boiling point, together with the favorable solvent properties of lower-molecular weight ethers and alcohols. The word "Cellosolve" was registered in 1924 as a United States trademark by Carbide & Carbon Chemicals Corp. for "Solvents for Gums, Resins, Cellulose Esters, and the Like". The first one was ethyl cellosolve, with the name now generic for glycol ethers.
In chemistry, an aza-crown ether is an aza analogue of a crown ether (cyclic polyether). While the parent crown ethers have the formulae (CH2CH2O)n, the parent azacrown ethers have the formulae (CH2CH2NH)n, where n = 3, 4, 5, 6. Well studied aza crowns include triazacyclononane (n = 3), cyclen (n = 4), and hexaaza-18-crown-6 (n = 6).
Triethyloxonium tetrafluoroborate is the organic oxonium compound with the formula [(CH3CH2)3O]BF4. It is often called Meerwein's reagent or Meerwein's salt after its discoverer Hans Meerwein. Also well known and commercially available is the related trimethyloxonium tetrafluoroborate. The compounds are white solids that dissolve in polar organic solvents. They are strong alkylating agents. Aside from the BF−
4 salt, many related derivatives are available.
Chloroalkyl ethers are a class of organic compounds with the general structure R-O-(CH2)n-Cl, characterized as an ether connected to a chloromethyl group via an alkane chain.
12-Crown-4, also called 1,4,7,10-tetraoxacyclododecane and lithium ionophore V, is a crown ether with the formula C8H16O4. It is a cyclic tetramer of ethylene oxide which is specific for the lithium cation.
15-Crown-5 is a crown ether with the formula (C2H4O)5. It is a cyclic pentamer of ethylene oxide that forms complex with various cations, including sodium (Na+) and potassium (K+), however, it is complementary to Na+ and thus has a higher selectivity for Na+ ions.
Bis(chloroethyl) ether is an organic compound with the formula O(CH2CH2Cl)2. It is an ether with two 2-chloroethyl substituents. It is a colorless liquid with the odor of a chlorinated solvent.
William Clark Still is an American organic chemist. As a distinguished professor at Columbia University, Clark Still made significant contributions to the field of organic chemistry, particularly in the areas of natural product synthesis, reaction development, conformational analysis, macrocyclic stereocontrol, and computational chemistry. Still and coworkers also developed the purification technique known as flash column chromatography which is widely used for the purification of organic compounds.
21-Crown-7 is an organic compound with the formula [C2H4O]7 and the IUPAC name of 1,4,7,10,13,16,19-heptaoxacycloheneicosane. Like other crown ethers, 21-crown-7 functions as a ligand for some metal cations with a particular affinity for caesium cations. The dipole moment of 21-crown-7 varies in different solvents and under different temperatures.
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![Structure of [Na(dibenzo-18-c-6)] , as found in the FeCl4 salt. Na(dibenzo18-c-6)FeCl4 (TITWIC).png](http://upload.wikimedia.org/wikipedia/commons/thumb/d/df/Na%28dibenzo18-c-6%29FeCl4_%28TITWIC%29.png/330px-Na%28dibenzo18-c-6%29FeCl4_%28TITWIC%29.png)