Grades methyl bromide

Isobutylene (Philips Research Grade) was purified as described [17] by distillation on a vacuum line through a trap containing sodium at 350 °C. It was stored as liquid on a sodium mirror. Solutions in methyl bromide were made up by distilling the required quantities of solvent and isobutylene from hanging burettes along a vacuum line into a reservoir with Teflon tap, which was subsequently cut from the vacuum line and fused to a burette with Teflon tap which was then fused to the main vacuum manifold as shown in Figure 1. 

To a large bottle are added 470.0 gm (5.6 moles) of 2-methyl-3-butyne-2-ol, 1000 ml of 48 % technical grade hydrobromic acid, 200.0 gm (2.04 moles) of ammonium bromide, and 70.0 gm (0.71 mole) of cuprous chloride. The bottle is sealed, shaken at room temperature for 4J hr, opened, and the organic layer is separated. The organic layer is washed twice with sodium bicarbonate solution, once with a saturated sodium bisulfite solution, dried over calcium chloride, and fractionally distilled through a glass-helix-packed column to afford 500 gm (61 %) of almost pure product (ir 1956 cm-1 allene), b.p. 34°C (18 mm), d5 1.5163. The ir showed that the product contained a trace of l-bromo-3-methyl-1,3-butadiene (1580 and 1620 cm-1). 

Mallinckrodt analytical reagent grade ether, dried over sodium, was used. The methyl borate was the commercial product of American Potash and Chemical Corporation containing 99% ester as received. The phenylmagnesium bromide was purchased as a 3.0M solution in ether from Arapahoe Special Products, Inc., Boulder, Colorado. 

The ethyl sec,-butylmalonate was prepared from sec-butyl bromide and malonic ester according to the general method described in Org. Syn. 4, n. The yield of ester boiling at i24-i32°/28 mm. was 80-81 per cent of the theoretical amount. The yields of 3-methyl pentanoic acid given in this procedure were obtained with this grade of ester. 

The methyl oleate was prepared by esterification1 of commercial u.s.p. grade oleic acid and fractionated through a Widmer column. The fractions used boiled at 140-144° (0.5 mm.), 175-179° (2 mm.), and had d 1.4500-1.4527 and an iodine number of 93-97 (calcd. 85.6) by iodine bromide titration.2... 

Materials Acety 1 cholinesterase from an electric eel, (EC 3.1.1.7,1 OOOU/mg), acetylthiocholine chloride, 5,5 -dithiobis (2-nitrobenzoic acid), D (+) trehalose dihydrate, D (+) glucose, pyridostigmine bromide, and neostigmine bromide were from Sigma Chemical/Aldrich. Aldicarb, carbaryl, carbofuran, chlorpyrifos, chlorpyrifos-oxon, dichlorvos, methomyl, malathion, malaoxon, naled, paraoxon, parathion, trichlorfon, azinphos-methyl, diclofenthion, dimethoate, dimethoate-oxon, terbufos, phosmet, and fenthion were obtained from Chem Service Corp. All others chemicals used were reagent grade. Deionized water (DI) was used for the preparation of all solutions. 

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