From cyclic ethers

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

Salen Metal Complexes as Catalysts for the Synthesis of Polycarbonates from Cyclic Ethers and Carbon Dioxide... 

Eight-membered heterocyclic systems embrace a very broad variety of compounds ranging from cyclic ethers and imines to highly labile analogs of cyclooctatetraene, and the properties and chemical behavior of these compounds of course depend entirely on the extent and location of unsaturation. For this reason, preparative methods and reactions are treated together for each ring system and oxidation level. 

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 1). The alky lens oxide polymerization is usually initiated by alkali hydroxides, especially potassium hydroxide. In the base-catalyzed polymerization of propylene oxide, some rearrangement occurs to give allyl alcohol. 

Formaldehyde homopolymer is composed exclusively of repeating oxymethylene units and is described by the term polyoxymethylene (POM) [9002-81-7]. Commercially significant copolymers, for example [95327-43-8], have a minor fraction (typically less than 5 mol %) of alkylidene or other units, derived from cyclic ethers or cyclic foimals, distributed along the polymer chain. The occasional break in the oxymethylene sequences has significant ramifications for polymer stabilization. 

Radicals formed by hydrogen abstraction from cyclic ethers are known to add readily to olefins (49), sinr oe-substituted cyclic ethers can... 

Friedel-Crafts alkylations. 1 -Substituted tetralins are obtained from cyclic ethers such as 2-(3-arylpropyl)tetrahydrofurans and alkyl Al-(l-hydroxy-4-arylbutyl) carbamates by treatment with TiCl. ... 

The procedure iliustrated here is representative of a generai and versatile method for the preparation of 2-substituted tetrahydrofurans and tetrahydropyrans from cyclic ether sulfones and the appropriate alkynyl, vinyl, or aryl Grignard reagent. From the examples shown in the Table and others previously reported, - a selectivity for the trans-product is observed with 6-substituted tetrahydropyrans irrespective of the initial geometry of the sulfone. This implies the presence of a common reaction intermediate such as an oxonium ion which is trapped by preferred axial bond... 

From numerous examples it is known that a-carbanions derived from cyclic ethers, including oxirancs, and from cyclic acetals retain the configuration of the starting material and therefore can be protonated stereoseiectively. 

Transfer hydrogenation. This ruthenium(II) complex is an effective catalyst for transfer of hydrogen from cyclic ethers, benzyl alcohol, and cyclohexanol to aldehydes and ketones. RuH2(CO)[P(C6H6)3]3 is somewhat less active. 

Without additional reagents Cleavage of ethers by sulfonates Acoxysulfonates from cyclic ethers... 

Bromine water Lactones from cyclic ethers... 

Lithium/irradiation Prim, alcohols from cyclic ethers -Hydroxy- -butylation of arenes with tetrahydrofuran... 

A mixture of octanol, a little hexadecyltrimethylammonium bromide, and 37% aq. HCl heated at reflux overnight 1-chlorooctane. Y 87% (Y 47% in the absence of micelles). Solubility of alcohols in coned, aq. HCl is considerably enhanced in micellar media, thereby effecting an inexpensive conversion to alkyl chlorides in high yield. F.e.s. B. Jursic, Synthesis 1988, 868-71 halogenative cleavage of ethers, inch dichlorides from cyclic ethers, and phenols and alkyl chlorides from phenolethers, s. J. Chem. Res. (S) 1989, 284 5. 

Hydroxyphosphonium salts from cyclic ethers and phosphines... 

Tetraphenylstibonium iodide Lactones from cyclic ethers and ketenes Regiospecihc conversion... 

Cyclic keteneacetals from cyclic ethers and ketenes s. 44, 575... 

Ketones from cyclic ethers and ethylene derivatives... 

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