Methylene iodide, preparation

Methylene bromide (CHjBfj) and methylene iodide (CHjIj) are easily prepared by the reduction of bromoform or iodoform respectively with sodium arsenite in alkaline solution ... 

In a 1-litre three-necked flask, fitted with a mechanical stirrer, reflux condenser and a thermometer, place 200 g. of iodoform and half of a sodium arsenite solution, prepared from 54-5 g. of A.R. arsenious oxide, 107 g. of A.R. sodium hydroxide and 520 ml. of water. Start the stirrer and heat the flask until the thermometer reads 60-65° maintain the mixture at this temperature during the whole reaction (1). Run in the remainder of the sodium arsenite solution during the course of 15 minutes, and keep the reaction mixture at 60-65° for 1 hour in order to complete the reaction. AUow to cool to about 40-45° (2) and filter with suction from the small amount of solid impurities. Separate the lower layer from the filtrate, dry it with anhydrous calcium chloride, and distil the crude methylene iodide (131 g. this crude product is satisfactory for most purposes) under diminished pressure. Practically all passes over as a light straw-coloured (sometimes brown) liquid at 80°/25 mm. it melts at 6°. Some of the colour may be removed by shaking with silver powder. The small dark residue in the flask solidifies on cooling. 

Methylene iodide [75-11-6], CH2I2, also known as diio dome thane, mol wt 267.87, 94.76% I, mp 6.0°C, and bp 181°C, is a very heavy colorless Hquid. It has a density of 3.325 g/mL at 20°C and a refractive index of 1.7538 at 4°C. It darkens in contact with air, moisture, and light. Its solubiHty in water is 1.42 g/100 g H2O at 20°C it is soluble in alcohol, chloroform, ben2ene, and ether. Methylene iodide is prepared by reaction of sodium arsenite and iodoform with sodium hydroxide reaction of iodine, sodium ethoxide, and hydroiodic acid on iodoform the oxidation of iodoacetic acid with potassium persulfate and by reaction of potassium iodide and methylene chloride (124,125). Diiodoform is used for determining the density and refractive index of minerals. It is also used as a starting material in the manufacture of x-ray contrast media and other synthetic pharmaceuticals (qv). 

In 1958 Simmons and Smith described a new and general synthesis of cyclopropanes by treatment of olefins with a reagent prepared from methylene iodide and a zinc-copper couple in ether solution. 

In this process the lOjS-methyl-3-keto-A -steroid is formed directly using a reagent prepared in situ with an approximately 1 1 molar ratio of zinc and methylene iodide. A one-step mechanism proceeding from the dienol (18) formed by Lewis acids present in solution has been proposed. ... 

The preparation of cyclopropane derivatives has been greatly facilitated by the development of carbene-type intermediates (see Chapter 13) and their ready reaction with olefins. The preparation of phenylcyclopropane from styrene and the methylene iodide-zinc reagent proceeds in only modest yield, however, and the classical preparation of cyclopropane derivatives by the decomposition of pyrazolines (first employed by Buchner in 1890) is therefore presented in the procedure as a convenient alternative. 

Phenylcyclopropane has been prepared by the base catalyzed decomposition of 5-phenylpyrazoline (33 %),2 by the reaction of 1,3-dibromo-l phenylpropane with magnesium (68%),3 and by the reaction of 3-phenylpropyltrimethylammomum iodide with sodium amide in liquid ammonia (80%)4 However, the method frequently used at present is the reaction of styrene with the methylene iodide-zinc reagent (32%)5... 

Piperonylic acid has been made by the oxidation of piperic acid,1 piperonal,1 safrole2 and isosafrole2 with potassium permanganate. It has also been prepared by the action of methylene iodide on protocatechuic acid 3 in the presence of alkali. 

Norcarane has been prepared by the reduction of 7,7-dichlo-ronorcarane with sodium and alcohol,6 and by the light-catalyzed reaction of diazomethane with cyclohexene.6 The reaction of cyclohexene with methylene iodide and zinc-copper couple represents the most convenient preparation of norcarane which is of high purity. 

Current interest in cyclopropanes is reflected by two preparations Norcarane from cyclohexene, methylene iodide, and zinc-copper couple (p. 72) illustrates a new way of adding a methylene... 

The analogous l,5-dihydro-37/-2,4-benzodithiepin system can be prepared by the reaction of 1,2-benzenedimethanethiol with either methylene iodide in the presence of base or with aldehydes or ketones in the presence of acid. 

Three common methods of production are described in the literature the action of iodine,1 sodium ethylate,2 or hydriodic acid 3 on iodoform. The last of these three methods has been worked out in more detail and is the one generally recommended for the preparation of methylene iodide in the laboratory. In addition, methylene iodide has been produced by the action of iodine on diazomethane 4 and by electrolysis of iodoacetic acid.5 It may also be made by the action of potassium iodide upon methylene chloride.Sa... 

The reduction of iodoform by means of sodium arsenite,6 described both by V. Auger and A. Gutmann, gave such successful results that the other methods were disregarded. The reaction is extremely simple and in the course of a few hours several pounds of pure methylene iodide may be prepared. 

It is possible that a dialkylzinc-methylene iodide reagent may further improve the yield as in the case with cyclopropanes prepared from vinyl ethers (Fura-kawa, J., Kawabata, N., Nishimura, J. Tetrahedron 24, 53 (1968)). 

Table II presents the results of some wettability measurements on adsorbed monolayers prepared from molten Compound D on pure, polished, clean, chromium surfaces after solvent treatment had been used to remove all surplus solidified acid. A series of successive solvent treatments was applied to each coated specimen (see first four columns of Table II) using liquids which have been shown to be good solvents for Compound in the bulk (9). These liquids were either absolute ethyl alcohol or benzene at or above 20°C., or n-hexane at or above 60°C. In the remaining columns are listed the average values of the slowly advancing contact angles measured by the drop-buildup method on from three to five different drops. Measurements were made on sessile drops of water, thiodiglycol, and methylene iodide. These three diagnostic liquids were chosen because of their high surface tensions (72.8, 54.0,...

Reaction of 1,2-benzenedimethanol 333 with aldehydes or related compounds gives l,5-dihydro-3//-2,4-benzodiox-epins 334 as exemplified in Scheme 180 <2001TL3183, CHEC-III(13.11.11.2)361>. The analogous benzodithiepin system 336 can be prepared by the reaction of 1,2-benzenedimethanethiol with methylene iodide in the presence of base or from the dibromide 335 and CS2 as shown in Scheme 181 <20000L1133, CHEC-III(13.11.9.4)356>. 

Methylene bromide has been prepared by the reaction of bromine with methylene iodide,1 and by the action of bromine on methyl bromide 2 at 250°. The present method is adapted from the preparation of methylene iodide described in Org. Syn. 1, 57. 

Ring closure of acylamines prepared from ethylenediamine also yields imidazoles,88 but this reaction will be discussed in Section II, E as formation of the 1 2- and 2 3-bonds. When 2,2 -dipyridyl compounds react with methylene iodide,84 bromine in pyridine, or p-toluenesulfonyl chloride in pyridine,85 imidazolium salts are produced. 

Methylene iodide is a very heavy, highly refractive liquid, which darkens on exposure to light, air, and moisture. It has a melting point of 6 Celsius, and a boiling point of 181 Celsius. Methylene iodide is insoluble in water, but is miscible with alcohol, hexane, cyclohexane, ether, chloroform, and benzene. It dissolves sulfur and phosphorus. Methylene iodide is prepared by reacting iodoform with sodium arsenite, or by heating iodoform with sodium acetate in 95% ethanol. 

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