W-Butyl ether

The preparation of di-w-butyl ether is illustrative (Scheme 2.6). No reaction occurred with n-butanol alone for 2 h at 200 °C. However, in the presence of 10 mol % n-butyl bromide, 26% conversion of the alcohol to the ether was obtained after 1 h, without apparent depletion of the catalyst. It is known that addition of alkaline metal salts can accelerate solvolytic processes, including the rate of ionization of RX [41]. This was confirmed when the introduction of LiBr (10 mol %) along with n-butyl bromide, afforded a conversion of 54% after 1 h at 200 °C. Ethers incorporating a secondary butyl moiety were not detected, precluding mechanisms involving elimination followed by Markovnikov addition. 

Di-tert-butyldiperphthalate [2155-71-7] M 310.3. Crystd from ethyl ether. Dried over H2SO4. Di-w-butyl ether see n-butyl ether. 

If, however, the water formed is removed as formed (compare the preparation of di-w-butyl ether, Section 111,57), the sulphuric acid may react completely and the method may be employed for the preparation of the free sulphonic acid. 

In a 5-I. flask, placed on a steam bath and fitted with a mechanical stirrer, a separatory funnel, a thermometer well (Note 1) and a calcium chloride tube, is placed 182 g. (7.5 moles) of magnesium turnings. To this is added a crystal of iodine and 100 cc. of a solution of 1133 g. (7.5 moles) of 2-bromo-pentane (Note 2) in 750 g. of -butyl ether (Note 3). The stirrer is started and the flask is heated with steam until the reaction starts. This may take from fifteen minutes to one hour, but the flask must be watched quite closely because the reaction, when once started, is very vigorous and evolves a large amount of heat. As soon as the reaction has started, 750 g. of w-butyl ether is added and then the balance of the solution of 2-bromo-pentane in w-butyl ether is added at such a rate that the temperature is kept at 50-60°. External cooling is used in order to allow more rapid addition of the 2-bromopentane. After addition is complete (about three hours), the mixture is heated on a steam bath for one hour. 

About 70 per cent of the w-butyl ether is recovered readily and may be purified by distillation. 

This procedure has been used successfully to convert simple aliphatic ethers into their corresponding iodides. Yields of iodides obtained in the reaction of di-w-butyl ether and diisopropyl ether with potassium iodide and 95% orthophosphoric acid were 81 and 90% respectively. Small quantities of the corresponding alcohols were also isolated as products from these reactions. 

Using equipment similar to that employed in the preparation of sodium diphenylphosphide, chlorotrimethylsilane (49.5 g., 0.45 mole, 59 ml.) dissolved in 100 ml. of dry w-butyl ether is added drop by drop to the refluxing, stirred suspension of sodium diphenylphosphide over a 2-hour period. After refluxing for an additional hour, the mixture is filtered and washed under nitrogen by means of a filtering stick similar to one previously described.11 The solvent is removed by distillation at atmospheric pressure, and the residual oil is fractionally distilled at 1 mm. pressure in a nitrogen atmosphere. In a typical experiment a 24.0-g. (62%) fraction is collected as product (b.p. 126-127°/1 mm., 1.600). 

Di-w-butyl ether is used in preference to other possible compounds because it permits the formation of a homogeneous reaction mixture. 

The first fractions consist of a little alcohol, water, and di-w-butyl ether (Note 5). The next fraction is diethyl sebacate, b.p. 156-158° at 6 mm. (Note 6). Ethyl hydrogen sebacate is collected at 183-187° at 6 mm. The product melts at 34-36° and weighs 114-124 g. (50-54 per cent of the calculated amount, based on the sebacic acid used). Refracfionation of the fore-run (b.p. i75-i83°/6 mm.) and after-run (b.p. i87-i95°/6 mm.) gives an additional 24-26 g. of pure monoester. The total yield is 138-150 g. (60-65 per cent of the theoretical amount) (Notes 7 and 8). 

This preparation is an example of the use of di- -butyl ether as a solvent in the Grignard reaction. The advantages are it is comparatively inexpensive, it can be handled without excessive loss due to evaporation, simple distillation gives an ether free from moisture and alcohol, and the vapour does not form explosive mixtures with air. w-Butyl ether cannot, of course, be employed when the boiling point of the neutral reaction product is close to 140 . 

The use of w-butyl ether allows the ready separation of the pentane by distillation. The butyl ether used in this preparation boiled at 142-144°. 

Diethylene glycol monomethyl ether [111-77-3] M 120.2, h 194°, d 1.010, n 1.423. Purify it as for diethylene glycol mono-w-butyl ether. [Beilstein 1IV 2392.]... 

Two phenyl ether derivatives (EPh and PPh) and dipropylene glycol w-butyl ether (DPnB) were the most effective coalescent solvents. Doty reported that DPnB continued as one of the most efficient coalescent solvents when tested with to five other acrylic emulsion resins. Other effective solvents in... 

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