A, iodide

This is typically accompHshed by cooling the titration solution with ice, determining the blank, and titrating rapidly. Another method utilizes deterrnination of the total peroxide and peracid content by use of a ceric sulfate titration to measure hydrogen peroxide followed by a iodide/thiosulfate titration to measure total active oxygen (60). 

Figure 1-7. The spectrochemical series arranges ligands in the order of their effect upon the magnitude of A. Iodide is a weak field ligand and gives small ligand field splittings, whereas carbon monoxide gives a strong field and a large A.

Fig. 14.33. A iodide —> periodinane oxidation exemplified by the preparation of the Dess-Martin reagent (see Figure 14.13 for a synthetics application).

Zoeller and coworkers at Eastman Chemical Company Research Laboratories have reported an efficient system for the carbonylation of ethylene based on a iodide-promoted... 

Tertiary alkyl halides are easier to reduce than secondary alkyl halides, which are, in turn, easier to reduce than primary alkyl halides. Ease of reduction of a carbon-halogen bond is governed by the identity of the halogen atom (a) iodides are easier to reduce than bromides, (b) chlorides are so difficult to reduce that they often appear to undergo no direct reduction, and (c) no report of the direct reduction of an alkyl monofluoride has been published. Finally, the existence of the radical anion [RX ], formed by addition of one electron to an alkyl monohalide, has never been demonstrated Andrieux and coworkers [8] have discussed why such a species is not expected for simple alkyl monohalides, but why radical anions of aromatic halides are distinct intermediates in the electrochemical reduction of aromatic halides. Canadell and coworkers [9] have described the implications of theoretical calculations pertaining to the lifetime of the water-solvated radical anion of methyl chloride. 

Methylneostrychnidinium iodide is formed when 20.0 g. of methoxymethyldihydro-neostrychnidine is dissolved in 300 cc. of 10% sulfuric acid and heated to boiling under an air condenser. In a short time methyl alcohol can be detected at the open end of the condenser, and when, after 2 hours, all of it has boiled away, the reaction mixture no longer gives a turbidity when made ammoniacal. The pale brown solution is made just alkaline with ammonia, and a little sulfurous acid and 25.0 g. of sodium iodide are added. The clear solution is rapidly filtered and vigorously stirred. The methylneo-strychnidinium-A iodide (there are two isomers) separates either as a heavy crystalline precipitate or as a gum which soon crystallizes. The iodide crystallizes in long needles from water containing a little sulfurous acid. The A-iodide darkens at 295° and decomposes to a black mass at 300°. 

While the isolation of des-base-A as one of the products of the Hofmann reaction has added further support for the structure assigned to methyl-(chano)-dihydroneostrychnidine, yet it is the isomeric des-base, anhydro-methylstrychnidinium-D hydroxide (des-base-D, m.p. 196-197°) that has provided a whole series of new compounds by a novel reaction. Introduction of two hydrogen atoms into des-base-D by catalytic reduction (palla-A solution of 9.0 g. of des-basc-D in 130 cc. of 10% hydrochloric acid is shaken with hydrogen at 17-19° in the presence of palladium-charcoal catalyst. The uptake of hydrogen ceases when 355 cc. of hydrogen (theory 600 cc.) is absorbed. Further addition fails even at 90°. The hot solution is filtered, made ammoniacal, and concentrated under vacuum to one-third its volume. The concentrate, when treated with a solution of 10 g. of sodium iodide in 10 cc. of water, yields a colorless precipitate which is a mixture of methyldihydrostrychnidinium-D iodide and methyldihydrostrychnidinium-A iodide. Repeated fractional crystallization from water yields 8.7 g. of the former (m.p. 325-327°) and 3.2 g. of the latter (m.p. 345-350°). 

Trimethyl-m-xylylphosphonium iodide, (CH3)3CgH9.PI.—The iodide obtained by treating dimethyl-m-xylylphosphine with methyl iodide is capable of existing in t-wo isomeric for ms The a-iodide... 

Trimethyl-m-xylylphosphonium iodide, (CH3)3CgH9.PI.—The iodide obtained by treating dimethyl-m-xylylphosphine with methyl iodide IS capable of existing in two isomeric forms The a-iodide crystaUises in scales or feathery needles, M.pt. 265° C., fairly soluble in water or alcohol and insoluble in ether. The -iodide forms bushy needles. It is possible that these compounds have the following formulae —... 

---