ACTION (W 1()M/!\G RADIATION ON SIMPLE ORGANIC: CIOMPOUNDS 



possible primary processes and so must be at least secondary products. As 

 the present interest is in the primary products, the proportions of these 

 secondary jiroducts would have no bearing on the primary product yield. 

 These higher iodides are known to be present, although exactly in what 

 form they are present is not known. 



Another product not mentioned in Table 1 is hydrogen iodide. This 

 compound has been identified in the gas chromatography as a peak that is 

 eluted at different times, depending on the history of the column in use. If 

 the column is new and still contains small amounts of aljsorbcd water, the 

 h)clrogen iodide is eluted slightly later than «-amyl iodide. However, if the 

 column has been used for several hours, at an elevated temperature, the 

 water present has been slowly eluted from the column, and the hydrogen 

 iodide appears with the methyl iodide. Final proof of the presence of 

 hydrogen iodide is that when the activity giving this peak was collected, by 

 trapping in liquid oxygen, the material was preferentially soluble in an 

 aqueous phase rather than an organic phase — (chloroform or hexane). This 

 can only be hydrogen iodide as both iodine and organic iodides arc more 

 soluble in the organic solvent. To avoid the complication of the hydrogen 

 iodide, small amounts of soda lime were included in the columns, preventing 

 the hydrogen iodide from being eluted. No complete analyses for hydrogen 

 iodide have been made, due to the difficulty in determining hydrogen iodide 

 with any accuracy. Rough analyses have shown that the hydrogen iodide 

 can be as high as 20 per cent of the total iodine at some stages in the 

 irradiation. 



If the irradiation mixture is distributed between an organic solvent such 

 as chloroform or petrol and an aqueous sodium sulphite solution, an estimate 

 of the organic and inorganic iodine can be obtained by counting each frac- 

 tion. By counting the activity eluted from the column an estimate of the 

 activity appearing as volatile organic iodides can be determined. 



Experiments have shown that if the radiolysis is continued for long periods, 

 the inorganic iodine is less than 1 per cent, showing that hydrogen iodide 

 is only a temporary product. There are other products which appear as 

 organic iodides but which are not eluted from the columns. These products 

 could be polyiodides, and it is hoped that these will be identified. 



The detection of hydrogen iodide, indicates that hydrogen atoms must be 

 present in the decomposition, formed by the reactions: 



C5H12 — > c,h;, + H- (9) 



and H + I2 > HI + V (10) 



I* is considered to be incapable of reacting as follows: 



r + C,H,2 > HI + C^H;, (//) 



The absence of such hydrogen abstraction processes means that hydrogen 

 atoms must be formed as primary fragments, in order that hydrogen iodide 

 should be found. A similar reaction to (77) occurs in the chlorination and 

 bromination of hydrocarbons, when a chain reaction is known to occur. 

 The G-values {i.e. molecules transformed per 100 eV absorbed), are high for 

 chlorination, but here are low (about four) suggesting that a chain process 



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