Dimethyl ether, reaction with oxygen

Tetrafluoroethylene Oxide TFEO has only been prepared by a process employing oxygen or ozone because of its extreme reactivity with ionic reagents. This reactivity may best be illustrated by its low temperature reaction with the weak nucleophile, dimethyl ether, to give either of two products (47) (eq. 10). 

When the reaction of perfluQro-3,4-dimethyl-3-hexene with methanol is performed in the presence of pyridine, a perfluorinated dihydrofuran is formed, probably by a process involving generation of an anionic oxygen atom by nucleophilic cleavage of a supposed intermediate ether [27] (equation 24)... 

Active Figure 2.5 The reaction of boron trifluoride, a Lewis acid, with dimethyl ether, a Lewis base. The Lewis acid accepts a pair of electrons, and the Lewis base donates a pair of nonbonding electrons. Note how the movement of electrons from the Lewis base to the Lewis acid is indicated by a curved arrow. Note also how, in electrostatic potential maps, the boron becomes more negative (red) after reaction because it has gained electrons and the oxygen atom becomes more positive (blue) because it has donated electrons. Sign in atwww. thomsonedu.com to see a simulation based on this figure and to take a short quiz. 

A similar reaction of 1,3-dimethyl ether p-t-Bu-calix[4]arene, abbreviated as (H2L), with Et2Zn affords a monomeric compound (EtZn)2(L) (169) with a less complex structure (Figure 84) °. The zinc atoms in this compound form a flat Zn—O—Zn—O arrangement together with the phenolate oxygen atoms. To each zinc atom one ethyl group is bonded, and tetrahedral coordination is reached by the additional coordination of one methoxy group. 

Olah and Bukala404 have developed a method for the oxidative carboxylation of methyl halides with CO and copper oxides or Cu and oxygen over SbF5-graphite [Eq. (5.156)]. Time-dependence studies indicated that the three products—methyl acetate, dimethyl ether, and methyl fluoride—were formed in parallel reactions. The reactivity of methyl halides shows the decreasing order MeBr > MeCl > MeF. 

The polymer redistribution reaction with functionalized dendrimers has been investigated by Van Aert et al. for the case of the transetherification of poly-(2,6-dimethyl-1,4-phenylene ether) (PPE) by means of phenols attached to dendrimers [143]. The number average molecular weight of the arms is controlled by the ratio of moles of PE units and the moles of added phenol. The phenols have been attached to poly(propylene imine) dendrimers by means of a tert-butyloxycarbonyl tyrosine(Scheme 19a). The redistribution rate is slow but can be increased by adding CuCl / 4-dimethylaminopyridine catalyst. Oxygen-free... 

Raw stock for the direct synthesis of methylchlorosilanes, methylchlo-ride, has such impurities as moisture, methyl alcohol, oxygen, sulfur dioxide, methylenechloride, dimethyl ether, carbon oxide and dioxide, etc. Most of them negatively affect the synthesis of methylchlorosilanes harmful impurities are chemisorbed on the active centres of contact mass and foul the copper catalyst, which naturally inhibits the reaction of methyl-chloride with contact mass. A similar situation is observed in the direct synthesis of ethylchlorosilanes. 

DOT CLASSIFICATION 5.1 Label Oxidizer SAFETY PROFILE Moderately toxic by intraperitoneal route. Severe skin and eye irritant. A powerful oxidizer which has caused many explosions in industry. Potentially explosive reactions with alkenes (above 220°C), ammonia, arjl hydrazine + ether, dimethyl sulfoxide + heat, ethylene oxide, fluorobutane + water, organic materials, phosphorus, trimethyl phosphate. Reacts to form explosive products with ethanol (forms ethyl perchlorate), cellulose + dinitrogen tetraoxide + oxygen (forms cellulose nitrate). Avoid contact with mineral acids, butyl fluorides, hydrocarbons. A drying agent. When heated to decomposition it emits toxic fumes of MgO and Cr. See also MAGNESIUM COMPOUNDS and PERCHLORATES. 

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