Dimethyl ether, atmosphere

In contrast to the silver process, all of the formaldehyde is made by the exothermic reaction (eq. 23) at essentially atmospheric pressure and at 300—400°C. By proper temperature control, a methanol conversion greater than 99% can be maintained. By-products are carbon monoxide and dimethyl ether, in addition to small amounts of carbon dioxide and formic acid. Overall plant yields are 88—92%. 

Ethers — (R-O-R) are low on the scale of chemical reactivity. Aliphatic ethers are generally volatile, flammable liquids with low boiling points and low flashpoints. Well known hazardous ethers include diethyl ether, dimethyl ether, tetrahydrofuran. Beyond their flammability, ethers present an additional hazard they react with atmospheric oxygen in the presence of light to form organic peroxides. 

A mixture consisting of 22.7 g potassium o-bromobenzoate, 16.6 g 2,6-dichloro-3-methvlani-line, 12 ml N-ethylmorpholine, 60 ml diethylene glycol dimethyl ether, and 1.0 g anhydrous cupric bromide is heated in a nitrogen atmosphere at 145 C to 155°C for 2 hours. The reaction mixture is diluted with 60 ml diethylene glycol dimethyl ether and acidified with 25 ml concentrated hydrochloric acid. The acidic mixture is diluted with 100 ml of water and the liquid phase decanted from the insoluble oil. The insoluble oil is stirred with methanol and the crystalline N-(2,6-dichloro-3-methylphenyl)anthranilic acid which separates is collected and washed with methanol. The product, after recrystallization from acetone-water mixture melts at 248 C to 250°C. 

The required working time is 3 to 4 hours. All equipment is thoroughly dried prior to use and is flushed with an inert gas (argon or nitrogen). Commercial sodium hydroborate is used without purification. The dimethyl ether of diethylene glycol (diglyme) is refluxed over calcium hydride for 8 hours and subsequently distilled over lithium tetrahydroaluminate (lithium aluminum hydride). Commercial tri-n-butylamine is refluxed with acetic anhydride and distilled at atmospheric pressure. 

Reflux 6.9 g triphenylphosphine and 6.6 g lauryl bromide (or equimolar amount of homolog) in 40 ml xylene for 60 hours. Remove solvent and wash residue with 5X20 ml ether (by decanting) to get 11 g lauryl triphenylphosphonium bromide (I). To a stirred suspension of 5.6 g (0.011M)(I) in 50 ml ether add 0.01M butyllithium solution (see Organic Reactions 8,258(1954) for preparation). Stir Vz hour at room temperature and slowly add 1.66 g 3,5-dimethoxybenzaldehyde (preparation given elsewhere here) in 10 ml ether over Vi hour. After 15 hours, filter, wash filtrate with water and dry, evaporate in vacuum. Dilute residue with pentane, filter and remove solvent. Dissolve the residual oil in 25 ml ethyl acetate and hydrogenate over O.lg Adams catalyst at one atmosphere and room temperature for 2 hours. Filter and evaporate in vacuum to get the 5-alkylresorcinol dimethyl ether which can be reciystallized from pentane and demethylated as described elsewhere here. 

B. Orcinol Monomethyl Ether. In a 1-1. three-necked flask equipped with a magnetic stirrer, a condenser, a dropping funnel, and a nitrogen inlet are placed 250 ml. of dry dimethyl-formamide (Note 6) and 22 g. (0.55 mole) of sodium hydride (60% oil dispersion). The suspension is stirred under an atmosphere of dry nitrogen and cooled with an ice bath while a solution of 31 g. (37 ml., 0.50 mole) of ethanethiol (Note 7) in 150 ml. of dry dimethylformamide (Note 6) is added slowly from the dropping funnel over a period of 20 minutes. The ice bath is removed and stirring is continued for an additional 10 minutes. A solution of 38.0 g. (36.5 ml., 0.25 mole) of orcinol dimethyl ether in 100 ml. of dry dimethylformamide (Note 6) is added in one lot, and the mixture is refluxed under an atmosphere of dry nitrogen for 3 hours (Notes 8 and 9), The mixture... 

The rate constants for the reactions between OH and a range of ethers and hydroxy ethers have been reported at 298 K233 as well as those for reactions between dimethyl ether and methyl f-butyl ether over the range 295-750 K.234 Data from the former study show deviations from simple structure-activity relationships which were postulated to arise due to H-bonding in the reaction transition states.233 The atmospheric lifetime of methyl ethyl ether has been determined to be approximately 2 days.235 Theoretical studies on the H-abstraction from propan-2-ol (a model for deoxyribose) by OH have been reported using ab initio methods (MP2/6-31G ).236 The temperature dependence (233-272 K) of the rate coefficients for the reaction of OH with methyl, ethyl, n-propyl, n-butyl, and f-butyl formate has been measured and structure-activity... 

General procedure for deprotection of mono- and polymethyl-aryl ethers with boron tribromide.41 To a 10-ml flask fitted with a septum and magnetic stirrer bar are added reactant (3.6 mmol) and 5 ml of dichloromethane. An inert atmosphere is established and maintained. This mixture is cooled in a dry ice/propan-2-ol bath and boron tribromide [0.13 ml, 1.32 mmol (for monomethyl ethers), or 0.38 ml, 4 mmol (for dimethyl ethers)] is added through the septum by use of a syringe. The cold bath is removed and the mixture stirred for 30 minutes, poured into ice water, stirred for 30 minutes, saturated with salt and extracted with dichloromethane. The extract is dried and concentrated. The purity of the product is established by h.p.l.c. analysis on a Waters Associates 6000A model using both refractive index and u.v. absorbance detectors with a Waters 3.9mm i.d. x 30cm p-Bondapack Ci8 reverse phase column. 

The atmospheric oxidation of dimethyl sulfide (DMS) and DMSO has been reviewed. Kinetics of oxidation of DMS and DMSO with OH and NO3 radicals and with halogen and halogen oxides have been described and the mechanistic aspects have been discussed.244 A review of recent studies of the mechanism and kinetics of the gas-phase oxidation of dimethyl ether has mentioned the pressure dependence of the... 

In a fume hood, 19.2 g. (0.059 mole) of tri-n-butyltin chloride and then 140 ml. of ethylene glycol dimethyl ether (monoglyme) which has been purified by distillation from calcium hydride at atmospheric pressure on an efficient fractionating column (fraction used boils at 85 1°C.) are added to a pressure-equalized 250-ml. dropping funnel, and the funnel gently agitated to dissolve all the tributyltin chloride. 

The Kinetics of Methanol Carbonylation Over RhX, RhY and IrY zeolites Carbonylation of methanol proceeds readily at atmospheric pressure under mild temperature conditions 150°-180°C. This reaction ZCH OH + CO - CH COOCH + HjO produces mainly methyl acetate and water. Acetic acid was detected at high conversions and high temperatures. Traces of dimethyl ether could also form. In most cases the selectivity to methyl acetate was at least 90% in presence of the iodide promotor. 

Nickel bromide ethylene glycol dimethyl ether (0.25 mmol) and the Step 1 product (0.32 mmol) were combined in a Schlenk flask under an argon atmosphere and 20 ml of CH2CI2 added. The mixture was stirred 24 hours at ambient temperature and then concentrated. The residue was washed three times with 10 ml of diethyl ether and dried the product was isolated as a dark-red powder in 85% yield. 

Diethyleneglycol dimethyl ether from Aldrich Chemical Co. was distilled under a nitrogen atmosphere and the fraction boiling at 161-2° was used. 

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