Oxidation alkoxylation

Alkoxylation Ethylene and/or propylene oxides Alkoxylated castor oils... 

Oxidative Alkoxylation of Nitrones to a-Alkoxy Nitrones and a-Alkoxy Substituted Nitroxyl Radicals The first direct experimental evidence of the possibility to carry out radical cation nucleophilic addition to nitrones with the formation of nitroxyl radicals has been cited in Section 2.4. Further, such a reaction route was referred to as inverted spin trapping this route is an alternative to a conventional spin trapping (508-512). Realization of either mechanism depends on the reaction conditions namely, on the strength of both nucleophile and oxidant. The use of strong oxidants in weak nucleophilic media tends to favour the radical cation mechanism... 

In addition to the oxidative alkoxylation of 4H -imidazole and oxazolidine derivatives, the reaction was also used with other cyclic aldo-nitrones such as DMPO, derivatives of 3-imidazoline-3-oxide (228-232) (506), and derivatives... 

It is relevant to note that only cyclic aldo-nitrones tend to react in oxidative alkoxylations to give a,a-dialkoxy-substituted nitroxyl radicals. However, the only exception is methylene nitrone (215), which on oxidative methoxylation gives the a,a,a-trimethoxy-substituted nitroxyl radical (277). This is due to the proton in methylene nitrone (215), which, as in the case of cyclic nitrones, exists in the cis -position to the TV-oxide oxygen (Scheme 2.104) (517). 

Mukaiyama et al. transformed the Co(II)-catalyzed hydrofunctionalizations (see Sect. 5.7) to intramolecular oxidative alkoxyl radical cyclizations by omission of the silane (Fig. 98). 4-Penten-l-ols 417 (R2=H) cyclized in the presence of 20 mol%... 

A niunber of 3-aryl- -phosphorins, 3-aryl-A --phosphorins, and 3-aryl-A -phosphorinium salts have been synthesized from oxaphosphorinium bromides (9). Spectral data indicate that in polar solvents l-chloro-3-phenyl-1-tert-butyl--A -phosphorin (10) is in equilibrium with 3-phenyl-1-fert--butyl-A -phosphorinium chloride (11). Thermolysis of derivative (10 Ph=aryl) yields the 3-aryl-A -phosphorin (12), which on oxidative alkoxylation with Hg(OAc)2/ntethanol affords the 3-aryl-1,1-dimethoxy-A -phosphorin (13) (Markl,... 

Alkenyl 1,3-diketones were reported as useful starting materials for the preparation of 2,3,5-trisubstituted furans via a palladium-catalyzed oxidative alkoxylation process. The alkenyl group can be allyl, homoallyl and 4-pentenyl <04JOC1738>. 

Coupling reactions with organic halides [62,71], cyclization addition of acetylenes with carbon dioxide, hydrogenations, reductions, oxidations, alkoxylations, ami-nations and insertions [100] have been reported as using nickel compounds. 

Intramolecular oxidative alkoxylation of olefins leading to oxygen heterocycles has also been reported. For example, treatment of 4-allyl-2,6-dimethyl-3,5-heptanedione with a catalytic amount... 

Heterocycles 12 323-327. doi 10.3987/R-1979-03-0323 Haddadin MJ, El-Khatib M, Shoker TA, Beavers CM, Olmstead MM, Fettigner JC, Farba- KM, Kurth MJ (2011) Quinoxalino[2,3-c]cinnolines and their 5-A-oxide alkoxylation of methyl-substituted quinoxalino[2,3-c]cinnolines to acetals and oithoesters. J Org Chem 76 (20) 8421-8427. doi 10.1021/jo201687x... 

Organic Reagents. Amine oxides are used ia synthetic organic chemistry ia the preparation of olefins, or phase-transfer catalysts (47), ia alkoxylation reactions (48), ia polymerization, and as oxidizing agents (49,50). 

TDA-derived polyols are made by alkoxylation. Polypropylene oxide adducts of I DA (14) and TDA-initiated polyether polyols (13,15) are used in rigid polyurethane foams and continue to be included in new formulations (62) as well as older appHcations. 

Etherification. Ethers of amyl alcohols have been prepared by reaction with ben2hydrol (63), activated aromatic haUdes (64), dehydration-addition reactions (65), addition to olefins (66—71), alkoxylation with olefin oxides (72,73) and displacement reactions involving thek alkah metal salts (74—76). 

Higher alkoxylated products, ie, oligomers, are formed by secondary reaction of oxide and the hydroxy group of the previous product. 

Hydrogen Sulfide andMercaptans. Hydrogen sulfide and propylene oxide react to produce l-mercapto-2-propanol and bis(2-hydroxypropyl) sulfide (69,70). Reaction of the epoxide with mercaptans yields 1-aLkylthio- or l-arylthio-2-propanol when basic catalysis is used (71). Acid catalysts produce a mixture of primary and secondary hydroxy products, but ia low yield (72). Suitable catalysts iaclude sodium hydroxide, sodium salts of the mercaptan, tetraaLkylammonium hydroxide, acidic 2eohtes, and sodium salts of an alkoxylated alcohol or mercaptan (26,69,70,73,74). 

Propylene oxide has found use in the preparation of polyether polyols from recycled poly(ethylene terephthalate) (264), haUde removal from amine salts via halohydrin formation (265), preparation of flame retardants (266), alkoxylation of amines (267,268), modification of catalysts (269), and preparation of cellulose ethers (270,271). 

Oxygen-Cont iiningAmines. This group includes amine oxides, ethoxylated alkylamines, l-(2-hydroxyethyl)-2-imidazolines, and alkoxylates of ethylenediamine. Oxygen-containing amines are steadily increasing in economic importance. 

Ethylenediamine Alkoxylates. The reaction 1,2-alkylene oxides with ethylenediamine forms the basis of a series of surfactants of the following general stmcture ... 

Aromatic ethers and furans undergo alkoxylation by addition upon electrolysis in an alcohol containing a suitable electrolyte.Other compounds such as aromatic hydrocarbons, alkenes, A -alkyl amides, and ethers lead to alkoxylated products by substitution. Two mechanisms for these electrochemical alkoxylations are currently discussed. The first one consists of direct oxidation of the substrate to give the radical cation which reacts with the alcohol, followed by reoxidation of the intermediate radical and either alcoholysis or elimination of a proton to the final product. In the second mechanism the primary step is the oxidation of the alcoholate to give an alkoxyl radical which then reacts with the substrate, the consequent steps then being the same as above. The formation of quinone acetals in particular seems to proceed via the second mechanism. ... 

Chloroquinoline (401) reacts well with potassium fluoride in dimethylsulfone while its monocyclic analog 2-chloropyridine does not. Greater reactivity of derivatives of the bicyclic azine is evident also from the kinetic data (Table X, p. 336). 2-Chloroquinoline is alkoxylated by brief heating with methanolic methoxide or ethano-lic potassium hydroxide and is converted in very high yield into the thioether by trituration with thiocresol (20°, few hrs). It also reacts with active methylene carbanions (45-100% yield). The less reactive 3-halogen can be replaced under vigorous conditions (160°, aqueous ammonia-copper sulfate), as used for 3-bromoquino-line or its iV-oxide. 4-Chloroquinoline (406) is substituted by alcoholic hydrazine hydrate (80°, < 8 hr, 20% yield) and by methanolic methoxide (140°, < 3 hr, > 90% yield). This apparent reversal of the relative reactivity does not appear to be reliable in the face of the kinetic data (Tables X and XI, pp. 336 and 338) and the other qualitative comparisons presented here. 

The reaction proceeds with high regioselectivity for oxidation at the less substituted a-carbon. Methanol is commonly used as the solvent, although higher alcohols are also used for some detailed experimental procedures refer to the literature60,61. Some examples of compounds prepared via electrochemical alkoxylation are ... 

Carbon-14 of the alkoxyl group in the polymer was also found during the treatment by other oxide polymerization catalysts containing the oxides Mo, W, V (195). By the character of the polarization of the active bond such systems may be designated coordinated cationic. ... 

Phosphoric acid esters based on alkylene oxide adducts are of great interest. Their properties can be altered by the length and structure of the hydrophobic alkyl chain. But they are also controlled by the kind and length of the hydrophilic alkyleneoxide chain. The latter can easily be tailored by selection between ethylene oxide and propylene oxide and by the degree of alkoxylation. 

If primary alcohols with a straight chain of 10-20 carbon atoms are initially alkoxylated by a mixture of ethylene and propylene oxides followed by phosphorylation, a pour point depression to 8°C will occur, whereas phosphate esters derived from nonylphenol are liquid at temperatures as low as 2°C. Phosphoric acid esters on the base of linear primary alcohols (Cn-Cl5) generally solidify below 24°C [50] (Table 2). 

This type of fission has been observed in a detailed examination of the oxidation of tertiary alcohols by Co(ril). The kinetics are similar to those reported for cyclohexanol vide supra) although the rate is about 40 times less. The possibility of alkoxyl radical formation seems attractive, for Co(III) is known to oxidise... 

Fig. 16.4 Interaction between quercetin (Quer) and iron and the balance between pro-oxidative and antioxidative effects. Quercetin may reduce Fe(H20) to yield Fe(H20) active in the Fenton region forming hydroxyl radicals ( OFI) or alkoxyl radicals ( OR), in effect being pro-oxidative. In contrast, quercetin may form a complex with iron(II), inactive in reducing FI2O2 to OFI, but rather oxidised in the quercetin ligand, in effect being antioxidative. Quer (-H) is the phenoxyl radical.

Alkoxylated polyethyleneimines are obtained by reacting polyethylene-imine with a molecular weight of 2500 to 35,000 with an excess of propylene oxide and ethylene oxide with respect to the ethyleneimine unit in the... 

In general, polyalkylene polyamides-amines are obtained by the condensation of polyalkylenepolyamines with dicarboxylic acids. The materials are alkoxylated with an excess of ethylene oxide or propylene oxide or 1,2-butylene oxide [149],... 

---