Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Thermal decomposition of hydrogen iodide

It is not possible to discuss the thermal decomposition of HI without at the same time discussing the HI synthesis. Until very recently it was common, particularly in Physical Chemistry textbooks, to find the reactions [Pg.147]

For the early stages of the synthesis, where reaction (6) may be neglected the overall rate is given by the expression [Pg.148]

From this equation the relative importance of the molecular and free radical processes can be calculated. At 575 °C the contribution of (5) to the overall reaction is small. For the thermal decomposition (6) alone will be important in the early stages of the reaction. [Pg.148]

In 1958 Semenov22 pointed out that an alternative mechanism existed for reaction (5) which would give rise to the same kinetic order as found experimentally, namely [Pg.148]

Since A/7298 [I2(g) - 21(g)] = 36.2 kcal.mole-1, then the apparent activation energy, Es — 41.4 kcal.mole-1 is sufficient to allow dissociation of iodine molecules with 5.2 kcal.mole-1 left for an activation energy ESll. [Pg.148]


Many second-order reactions follow Class I rate expressions. Among these are the gas-phase thermal decomposition of hydrogen iodide (2HI - H2 + I2), dimerization of cyclopen-tadiene (2C5H6 -> C10H12), and the gas phase thermal decomposition of nitrogen dioxide (2N02 2NO + 02). [Pg.29]

Typical among the examples of second-order reactions of type I are the gas-phase thermal decomposition of hydrogen iodide, 2HI —> H2 + I2 the gas-phase thermal decomposition of NO2, 2NO2 2NO + O2 the liquid-phase decomposition of C10 ion, 2C10 " —> 2C1 + 62 and the dimerization of cyclopentadiene in either gas or liquid phase, 2C5H6 —> C10H12. Actually, type I reactions are relatively rare in comparison with type II reactions. [Pg.17]

Another instance of the same curious phenomenon can be cited. Hydrogen has a most pronounced inhibiting effect on the thermal decomposition of ammonia at the surface of a heated platinum wire. On the other hand, it is found to be almost without influence on the decomposition of hydrogen iodide on the surface of the same wire, Compt. Rend., 1922, 175, 277. [Pg.248]

Kinetic studies of the thermal decomposition of alkyl iodides are complicated by the occurrence of secondary reactions between hydrogen iodide and the alkyl iodide to produce iodine and an alkane, viz. [Pg.183]

The amount of decomposition may be decreased by mixing the salt with a small amount of pure ammonium iodide before melting. The ammonia and hydrogen iodide, which result from the thermal decomposition of the ammonium iodide, repress the decomposition of the alkali iodide by a mass-action effect. [Pg.163]

Methyl />-tolyl sulfone has been prepared by oxidation of methyl 7>-tolyl sulfide with hydrogen peroxide 4 r or ruthenium tetroxide,6 by alkylation of sodium -toluenesullinate with methyl iodide 7,8 or with methyl potassium sulfate,9 by decarboxylation of -tolylsulfonylacetic acid,7 by thermal decomposition of tetramethylammonium -toluenesulfinate,10 by reaction of cw-bis-(%tolylsulfonvl)-ethene with sodium hydroxide (low yield),11 by the reaction of methanesulfonyl chloride with toluene in the presence of aluminum chloride (mixture of isomers),12 by... [Pg.64]

In aU known compounds, actinium appears as Ac with the radon structure, the hydrated ion occurring in aqueous solutions of its salts. Thorium salts give Th + ions. The identification of halides of Th and Th Ms questioned solids resulting from the thermal decomposition of Thl4 liberate hydrogen from water, the thorium being oxidised to Th, presumably, if a lower iodide is formed, by the reaction ... [Pg.442]

Translationally hot species may also have enhanced reaction rates. Reuben and Linnett have proposed that such hot oxygen atoms are formed in the thermal decomposition of nitrous oxide, and that these react at an accelerated rate with further nitrous oxide. Williams and Ogg have shown that hydrogen atoms with 42 kcal.mole" of translational energy react at an enhanced rate with hydrogen iodide, and have demonstrated a similar effect in the reactivity of hot methyl radicals. [Pg.283]

Two methods for the preparation of rhenium (II I) iodide are described below. In one procedure (A), perrhenic acid, obtained by reaction of 30% hydrogen peroxide on powdered rhenium metal, is reduced directly to the triiodide by the action of concentrated hydriodic acid and ethanol at elevated temperatures. The second procedure (B) utilizes the controlled thermal decomposition of rhenium(IV) iodide in an atmosphere of iodine. The tetraiodide is prepared by reduction of perrhenic acid with concentrated aqueous hydriodic acid, followed by dehydration of the initial product. [Pg.185]

The reduction of alkyl hahdes has been important in many syntheses. Sodium cyanoborohydride in HMPA will reduce alkyl iodides, bromides, and tosylates selectively in the presence of ester, amide, nitro, chloro, cyano, alkene, epoxide, and aldehyde groups [118]. Tri-n-butyltin hydride will replace chloro, bromo, or iodo groups with hydrogen via a free radical chain reaction initiated by thermal decomposition of AIBN [119]. Other functionality such as ketones, esters, amides, ethers, and alcohols survive unchanged. The less toxic tris(trimethylsilyl) silane can be used similarly [120]. [Pg.191]

Methyldihydrostrychnidinium-A acetate is produced in much small amount in the hydrogenation ( internal alkylation) reaction and w isolated as the iodide, m.p. 345-350°, and converted to the chloric which on treatment with sodium methoxide gave methoxymethyltetr hydrostrychnidine (c in the above list) with some des-base-D, and < thermal decomposition yielded dihydrostrychnidine-A. These and oth reactions of des-base-D are regarded as best accounted for by formu (XVIII). ... [Pg.578]

Bonhoeffer and Farkas estimated k3/k2 100 and claimed that at 15 % decomposition the photolysis is completely self inhibited. More recent work by Ogg and Williams9,10 showed that for the photolysis with 2537 A radiation, k3/k2 is independent of HI pressure (50-150 torr), independent of temperature and has a value 3.5+0.3. The effect of cyclohexane as an inert diluent11 was to increase k3/k2 to 7.0+0.4 at 155°, which value remained constant at high cyclohexane hydrogen iodide ratios. This result was attributed to collisional thermalisation of the hot H atoms produced by 2537 A radiation and this limiting high-pressure value of k3/k2 = (k3/k2)aa was considered to be that for thermally equilibrated H atoms. [Pg.145]


See other pages where Thermal decomposition of hydrogen iodide is mentioned: [Pg.296]    [Pg.16]    [Pg.147]    [Pg.149]    [Pg.82]    [Pg.46]    [Pg.94]    [Pg.446]    [Pg.342]    [Pg.296]    [Pg.16]    [Pg.147]    [Pg.149]    [Pg.82]    [Pg.46]    [Pg.94]    [Pg.446]    [Pg.342]    [Pg.141]    [Pg.282]    [Pg.275]    [Pg.154]    [Pg.242]    [Pg.383]    [Pg.154]    [Pg.328]    [Pg.363]    [Pg.116]    [Pg.102]    [Pg.159]    [Pg.625]    [Pg.304]    [Pg.33]    [Pg.394]    [Pg.448]    [Pg.270]    [Pg.227]    [Pg.953]    [Pg.155]    [Pg.155]    [Pg.50]    [Pg.287]    [Pg.1240]    [Pg.460]    [Pg.247]   


SEARCH



Hydrogen decomposition

Hydrogen iodid

Hydrogen iodide

Hydrogen iodide decomposition

Hydrogen thermal decomposition

Hydrogenation, thermal

Thermal decomposition

© 2024 chempedia.info