Iodoform, preparation reduction

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

Bismuth subnitrate [1304-85-4] (basic bismuth nitrate) can be prepared by the partial hydrolysis of the normal nitrate with boiling water. It has been used as an antacid and in combination with iodoform as a wound dressing (183). Taken internally, the subnitrate may cause fatal nitrite poisoning because of the reduction of the nitrate ion by intestinal bacteria. 

Bromo- and iodocyclopropanes cannot be prepared by the direct halogenation of cyclopropanes. Substituted chloro- and bromocyclopropanes have been synthesized by the photochemical decomposition of a-halodiazomethanes in the presence of olefins iodocyclopropanes have been prepared from the reaction of an olefin, iodoform and potassium f-butoxide followed by the reduction of diiodocyclopropane formed with tri-w-butyl tin hydride. The method described employs a readily available light source and common laboratory equipment, and is relatively safe to carry out. The method is adaptable for the preparation of bromo- and chlorocyclopropanes as well by using bromodiiodomethane or chlorodiiodomethane instead of iodoform. If the olefin used will give two isomeric halocyclopropanes, the isomers are usually separable by chromatography. ... 

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. 

Vinyl halides represent yet another important class of intermediates in the conversion of ketones to alkenes. The most widely applied conditions for the conversion of ketones into vinyl halides are those developed by Barton et a/. ° for the conversion of 3p-acetoxyandrost-5-ene-17-one into 3P-hydroxyandrosta-5,16-diene (Scheme 44). These conditions of vinyl halide formation and subsequent reduction have been useful in a number of steroid systems for the introduction of a A -carbon-carbon double bond and have been shown to be compatible with such functional groups as alcohols, isolated double bonds and acetals. The scope of vinyl iodide formation from hydrazones has been studied by Pross and Stemhell, and recently the original reaction conditions were improved by using sterically hindered guanidine bases rather than triethylamine. Haloalkenes have also been prepared from the corresponding ketones by treatment with iodoform and chromium chloride or with phosphorous penta-halides. ... 

Newer methods of chemical analysis led to the isolation of the major alkaloids from crude drug preparations. By 1833, aconitine, atropine, codeine, hyoscyamine, morphine, nicotine, and strychnine had been isolated from plants. Color tests for alkaloids were developed between 1861 and 1882 by 1890 quantitative analysis methods became available. Physiological tests for alkaloids, particularly strychnine, first used in 1856, were employed well into the twentieth century. Tests for alcohol, devised by Lieben (iodoform crystal test, 1870) and others, were later perfected for the quantitative analysis of alcohol in body fluids and tissues. Qualitative tests for carbon monoxide in the blood were developed about this time and in 1880, Fodor developed a palladium chloride reduction method to quantitate carbon monoxide in blood. 

The fact that the Simmons-Smith reaction is regio- and stereoselective enabled the preparation of tritium containing cyclopropane derivatives useful for biological studies. The tritiated diiodomethane was prepared by reduction of iodoform with sodium arsenite in the presence of tritiated water. The carbene generated from tritiodiiodomethane and triisobutylaluminum in chloroform underwent regioselective addition to the unhindered double bond in perillyl alcohol (34). ... 

Acid-sensitive t-alcohols can be dehydrated by a process that is related to the Chugaev reaction but which takes place at much lower temperatures (refluxing THF) (Scheme 9). u/c-Diols react with iodoform, triphenylphosphine, and imidazole to give the corresponding olefin, probably via reductive elimination from a di-iodo intermediate this method is particularly useful for preparing unsaturated sugars. 

Though half of the label gets lost as p- Cjacetate when [1,3- C2]acetone is treated with iodine, this reaction is still a standard preparation procedure for [ " C]iodoform. This compound is an indispensable precursor for [ C] methylene iodide , which is obtained by reduction of with sodium arsenite in alkaline medium. Diiodo[ " C]methane in... 

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