Iodide methyl

A mixture of methyl iodide (48 ml) and dimethyl sulfoxide (26 g) is heated under reflux for 3 days, cooled and the precipitated trimethylsulfoxonium 

Trimethylsulfoxonium iodide (38 g) is dissolved in deuterium oxide (170 ml) at 80-100° and anhydrous potassium carbonate (50 mg) is added. The mixture is heated on a steam bath for 1 hr, then cooled to 0° for 2 hr before filtering. The recovered solid is re-equilibrated twice more by the same procedure using fresh deuterium oxide. Yield = 33.4 g (88 %). 

The recovered dg-dimethyl sulfoxide may be recycled to prepare additional deuteriomethyl iodide or purified for use as a reagent by gentle warming with a little solid sodium thiosulfate followed by distillation from barium oxide. Both products show 99% deuteration.  

Iodtke is slowly washed by means of condensed liquid into a mixture of methyl alcohol and phosphorus. The apparatus employed by the author, Fig. 1, is rendered more flexible by the use of a three-necked flask, as shown in Fig. 2, and a further improvement is in the provision of a side tube for the addition of iodine to the separatory funnel, A (Note 1). In the following description reference is made to the simpler apparatus, Fig. 1 the changes required for the modified assembly will be obvious. 

The cylindrical separatory funnel A has a volume of 1200 cc. and holds 2 kg. (15.75 gram atoms) of iodine crystals (Note 2). A piece of perforated platinum foil B, or a loose plug of glass wool, is placed in the bottom to prevent clogging of the stopcock by iodine crystals or solid impurities. Stopcock C is as large as 5 mm. in bore as a further precaution. For the production of up to 4 kg. of methyl iodide, a 5-I. round-bottomed Pyrex flask D is used (Note 3). It is partly submerged in a water bath. Tube E, fitted into the reaction flask by a rubber stopper, is at least 2.5 cm. in internal diameter in order to allow the vapor to rise without interrupting the return of the excess distillate. Tube F is 4 cm. in diameter to allow for preliminary condensation. A space (13 cm.) is left above stopcock G as a reservoir for the distillate. Stopcock G has a bore of 2 or 3 mm. (Note 4). The bottom of the tube from this stopcock is flush with the bottom of the rubber stopper to the iodine container, so that the 

J 2 kg. of iodine, no crystals being allowed to fall below the platinum foil or glass wool. The iodine is covered with part of 2000 cc. (50 moles) of methanol (Note 7), the rest of which is added to 200 g. each of red and yellow phosphorus (12.8 gram atoms) in reaction flask D. 

The apparatus is assembled as illustrated in Fig. 1. The water bath is heated to 70-750 stopcock G is opened wide and stopcock C part way to allow the solution of iodine to flow slowly into the reaction flask. By the time that all the alcohol has been added, enough methyl iodide will have been formed to start the refluxing. Stopcock C is then opened wide and stopcock G partly closed so that only a small stream of methyl iodide flows through the iodine container. The temperature is adjusted so that little of the reflux flows back through tube E. This will require the progressive lowering of the water bath 

The discoloration of purified methyl iodide is greatly retarded by the addition of a drop of mercury, and traces of iodine in an old sample may be removed by shaking with mercury (Note 12). A very highly colored product is best washed with very dilute sodium thiosulfate, then with water, before drying. 

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After the primary step in a photochemical reaction, the secondary processes may be quite complicated, e.g. when atoms and free radicals are fcrnied. Consequently the quantum yield, i.e. the number of molecules which are caused to react for a single quantum of light absorbed, is only exceptionally equal to exactly unity. E.g. the quantum yield of the decomposition of methyl iodide by u.v. light is only about 10" because some of the free radicals formed re-combine. The quantum yield of the reaction of H2 -f- CI2 is 10 to 10 (and the mixture may explode) because this is a chain reaction. 

Zaera F and Floffmann FI 1991 Deteotion of ohemisorbed methyl and methylene groups surfaoe ohemistry of methyl iodide on Pt(111) J. Phys. Chem. 95 6297-303... 

Purdie t Methody also chiefly for hydroxy compounds. The substance is mixed with a small excess of dry silver oxide, and then shaken (or, if necessary, heated) with methyl iodide, a smooth methylation usually occurring. 

In view of the high cost of methyl iodide in the above preparation of anisole, and the fact that, unless absolute methanol is used, the ready hydrolysis of the methyl iodide may cause a low yield of the ether, the preparation of anisole may be ad antageously replaced by that of phenetole. I he reaction is not of course a methylation, but is nevertheless of the same type as that used in the preparation of anisole. 

When the sodium derivative, which is used in ethanol it solution without intermediate isolation, is boiled with an alkyl halide, e.g., methyl iodide,... 

When the methyl-phenyl-pyrazolone is heated with methyl iodide in methano-lie solution, it acts in the form (D), the — NH— group undergoing methy lation, with the formation of the hydriodide of 2,3-dimethyl- l-phenyl-5 Pyrazolone, or antipyrine (F), a drug used (either as the free base or as the... 

Substitution Derivatives of Ethyl Malonate, Ethyl malonate resembles ethyl acetoacetate in that it gives rise to mono- and di-substituted derivatives in precisely similar circumstances. Thus when ethanolic solutions of ethyl malonate and of sodium ethoxide are mixed, the sodium derivative (A) of the enol form is produced in solution. On boiling this solution with an alkyl halide, e.g, methyl iodide, the methyl derivative (B) of the keto form is obtained. When this is treated again in ethanolic solution with sodium ethoxide, the... 

Quinaldine Methiodide. Boil a mixture of 3 ml. of quinaldine, 2 ml. of methanol and 3 ml. of methyl iodide gently under reflux for hours, during which the methiodide will start to cry stallise. Cool the mixture thoroughly in ice-water, filter off the methiodide and recrystallise it from ethanol pale yellow crystals, m.p. 194". 

If, for example, methyl iodide is added to a solution of arsenic trioxide in an... 

Methyl iodide, ethyl bromide and iodide, higher alpihatic halides chloroform, iodoform, carbon tetrachloride chlorobenzene, bromobenzene, iodobenzene benzyl chloride. 

Members of Classes (i), (ii) and (iv) usually react readily with methyl iodide to give methiodides, i.e., quaternary ammonium iodides. 

Methiodide formation. Place 2 drops of dry pyridine in a dry test-tube, add 4-5 drops of methanol, and 2 -3 drops of methyl iodide. 

B) Methiodi s. Members of Classes (i), (ii) and (iv) combine wdth methyl iodide (some very vigorously) to form quaternary methiodides. It is best to add the amine to an excess of methyl iodide dissolved in about twice its volume of methanol, allow any spontaneous reaction to subside, and then boil under reflux for 30 minutes (extend to 1 hour for Class (iv) except pyridine and quinoline). The methiodide may crystallise when the reaction-mixture cools if not, evaporate the latter to small bulk or to dryness, and recrystallise, (M.ps., pp. 553-554 )... 

Physical Properties. All heavier than, and insoluble in water. All liquids, except iodoform, CHI3, which is a yellow crystalline solid with a characteristic odour. The remainder are colourless liquids when pure ethyl iodide, CjHjI, and iodobenzene, CjHgl, are, however, usually yellow or even brown in colour. Methyl iodide, CH3I, ethyl bromide, CgH Br, ethyl iodide, chloroform, CHCI3, and carbon tetrachloride, CCI4, have sweetish odours, that of chloroform being particularly characteristic. 

I. Reaction with cold silver nitrate solution. Add 2 ml. of 10% aqueous AgNOg solution to i ml. of methyl iodide and shake vigorously a yellow precipitate of Agl is formed in the cold. Add an excess of dil. HNO3 to show that the precipitate does not dissolve.f... 

Similar results are obtained with methyl iodide, ethyl bromide, ethyl iodide, iodoform, carbon tetrachloride, and benzyl chloride. 

Methyl iodide, ethyl bromide and ethyl iodide also evolve small amounts of ethylene when treated as above. If this is suspected, a small quantity of the substance should be heated with alcoholic NaOH solution in a small flask, fitted with a knee delivery-tube. Pass the gas evolved through a very dilute solution of KMn04 which has been made alkaline with aqueous NagCOj solution. If ethylene has been formed, a brown precipitate of MnOj will be produced (a transient green colour may appear). 

Pyridine methiodide and ethiodide. Place 2 drops of dry pyridine in a test-tube, add 2 drops of methyl iodide and mix. A vigorous reaction occurs and on cooling, a colourless crystalline mass of pyridine methiodide, CjHjN.Mel, is formed cf. p. 377) when recrystallised from methylated spirit, the methiodide has m.p. 117. ... 

Heat under reflux i g. of anisole and 10 ml. of constant-boiling hydrogen iodide for 30 minutes. Now distil off the volatile methyl iodide and identify it in the distillate (see pp. 390-391). 

I he methyl iodide is transferred quantitatively (by means of a stream of a carrier gas such as carbon dioxide) to an absorption vessel where it either reacts with alcoholic silver nitrate solution and is finally estimated gravimetrically as Agl, or it is absorbed in an acetic acid solution containing bromine. In the latter case, iodine monobromide is first formed, further oxidation yielding iodic acid, which on subsequent treatment with acid KI solution liberates iodine which is finally estimated with thiosulphate (c/. p. 501). The advantage of this latter method is that six times the original quantity of iodine is finally liberated. 

The Evolution of Methyl Iodide. The flask A (Fig. 89) is now heated with the non-luminous flame of the micro-burner. The immediate result of the heating will be an increase in the rate of bubbles passing up the absorption spiral no endeavour should be made to decrease this flow, however, as it will return to the original rate as soon as the hydro-... 

Methyl Iodide. Use 38 g. (48 ml.) of methyl alcohol, 8-27 g. of purified red phosphorus and 127 g. of io ne. Cover the iodine completely with the hot methyl alcohol before running the alcoholic solution into the boiling alcohol - phosphorus mixture. B.p. 42-42-5°. 

If the temperature is allowed to rise, the yield is slightly diminished owing to the formation of a little methyl iodide. 

Methiodides. Methyl iodide reacts with tertiary amines to form the crystalline quaternary ammonium iodide (methiodide) ... 

Allow a mixture of 0-5 g. of the tertiary amine and 0-5 ml. of colourless methyl iodide to stand for 5 minutes. If reaction has not occurred, warm under reflux for 5 minutes on a water bath and then cool in ice water. The mixture will generally set solid if it does not, scratch the sides of the tube with a glass rod. RecrystaUise the solid product from absolute alcohol, ethyl acetate, acetone, glacial acetic acid or alcohol-ether. 

Alternatively, dissolve 0-5 g. of the tertiary amine and 0-5 ml. of methyl iodide in 5 ml. of dry ether or benzene, and allow the mixture to stand for several hours. The methiodide precipitates, usually in a fairly pure state. Filter, wash with a little of the solvent, and recrystallise as above. 

Keep a coil of copper wire (prepared by winding copper wire round a glass tube) or a little silver powder in the bottle, which should be of brown or amber glass the methyl iodide will remain colourless indefinitely. Ethyl iodide may sometimes give more satis factory results. 

Pure -xylene may be prepared from p tolyl-sodium and methyl iodide or methyl sulphate. 

The methyl iodide molecule is studied using microwave (pure rotational) spectroscopy. The following integral governs the rotational selection rules for transitions labeled J, M, K... 

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