Reactions involving saturated hydrocarbons

Interaction of chlorine with methane is explosive at ambient temperature over yellow mercury oxide [1], and mixtures containing above 20 vol% of chlorine are explosive [2], Mixtures of acetylene and chlorine may explode on initiation by sunlight, other UV source, or high temperatures, sometimes very violently [3], Mixtures with ethylene explode on initiation by sunlight, etc., or over mercury, mercury oxide or silver oxide at ambient temperature, or over lead oxide at 100°C [1,4], Interaction with ethane over activated carbon at 350°C has caused explosions, but added carbon dioxide reduces the risk [5], Accidental introduction of gasoline into a cylinder of liquid chlorine caused a slow exothermic reaction which accelerated to detonation. This effect was verified [6], Injection of liquid chlorine into a naphtha-sodium hydroxide mixture (to generate hypochlorite in situ) caused a violent explosion. Several other incidents involving violent reactions of saturated hydrocarbons with chlorine were noted [7],... 

These reactions are of particular interest as they could provide the basis for a number of catalytic processes involving saturated hydrocarbons. 

The observation of 1-t rt-butyladamantane in the superacid-catalyzed reactions of adamantane with butenes provides unequivocal evidence for the (j-alkylation of adamantane by the tert-huty cation. As this involves an unfavorable sterically crowded tertiary-tertiary interaction, it is reasonable to suggest that similar (j-alkylation can also be involved in less strained interactions with secondary and primary alkyl systems. Although superacid-catalyzed alkylation of adamantane with olefins occurs predominantly via adamantylation of olefins, competing direct cr-alkylation of adamantane can also occur. As the adamantane cage allows attack of the alkyl group only from the front side, the reported studies provide significant new insight into the mechanism of electrophilic reactions at saturated hydrocarbons and the nature of their carbocationic intermediates. 

For saturated hydrocarbons, exchange is too slow and reference points are so uncertain that direct determination of pAT values by exchange measurements is not feasible. The most useful proach to obtain pK data for such hydrocarbons involves making a measurement of the electrochemical potential for the reaction... 

Hydrocarbon Reactions. Some interesting features of reactions involving olefins and saturated hydrocarbons are shown by investigating the effects of translational energy. The reactions ... 

Barium oxide is not a catalyst all reactions involving this component are entirely stoichiometric. Nevertheless, as Fig. 10.10 illustrates, even when the barium storage function is saturated, the NOx content in the outlet gas from the catalyst is lower than in the inlet, owing to the capability of platinum to reduce NOx by hydrocarbons in oxygen-rich exhausts. 

The nature of dangerous reactions involving organic chemicals depends on the saturated, unsaturated or aromatic structures of a particular compound. Saturated hydrocarbons are hardly reactive, especially when they are linear. Branched or cyclic hydrocarbons (especially polycyclic condensed ones) are more reactive, in particular as with oxidation reactions. With ethylenic or acetylenic unsaturated compounds, the products are endothermic . 

Nitroxyl radicals (AmO ) are known to react rapidly with alkyl radicals and efficiently retard the radical polymerization of hydrocarbons [7]. At the same time, only aromatic nitroxyls are capable of reacting with alkylperoxyl radicals [10,39] and in this case the chain termination in the oxidation of saturated hydrocarbons occurs stoichiometrically. However, in the processes of oxidation of alcohols, alkenes, and primary and secondary aliphatic amines in which the chain reaction involves the HOT, >C(0H)02 , and >C(NHR)02 radicals, possessing the... 

In most cases the slow step of the reaction is not simply the activation or chemisorption of hydrogen, but involves other chemisorbed species. Thus, the exchange of deuterium with methane and with other saturated hydrocarbons is much slower than with hydrogen and probably proceeds through dissociative adsorption of the hydrocarbon. 

The reactivity of surface methoxy species was further investigated with various probe molecules that were thought to possibly be involved in the MTO process, including water, toluene (representing aromatics), and cyclohexane (representing saturated hydrocarbons) (263). It was found that surface methoxy species react at room temperature with water to form methanol, which indicates the occurrence of a chemical equilibrium between these species at low reaction temperatures (Scheme 15) (263). 

Besides the oxygen atom reactions discussed earlier, we studied those involving I.2-C2H4CI2,66 NH3,66 and acetylene, cyclohexane, and benzene. At first attempts were made to find an O atom reaction that would be similar and at the same time essential for all substances. This is the ease, for example, for hydrogen atoms and hydroxyl. Hydrogen reacts with saturated hydrocarbons by abstraction of the H atom, and with unsaturated hydrocarbons by addition as well. Hydroxyl is believed to react with hydrocarbons by abstraction of the H atom and formation of water. 

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