Oxygen reactions with alkanes

Reaction with oxygen occurs during combustion in an engine or furnace when the alkane is used as a fuel. Carbon dioxide and water are formed as products, and a large amount of heat is released. For example, methane (natural gas) reacts with oxygen according to the equation... 

When alkanes react with oxygen a complex series of reactions takes place, ultimately converting the alkane to C02 and H20. 

Alkanes—Continued reactions—Continued with ozonide ions, 135 with superoxide ions, 134-35 role of oxygen ions in oxidation. 138-41 Alkenes, reactions with oxygen ions, 134 with ozonide ions, 135 with superoxide ions, 134-35 Aluminosilicate gels, alkali cations, 241... 

Alkanes undergo combustion reaction with oxygen at high temperatures to produce carbon dioxide and water. This is why alkanes are good fuels. Oxidation of saturated hydrocarbons is the basis for their use as energy sources for heat, e.g. natural gas, liquefied petroleum gas (LPG) and fuel oil, and for power, e.g. gasoline, diesel fuel and aviation fuel. 

Most of the alkanes from petroleum are used to produce energy by combustion, but a few percent are converted to industrially useful compounds by controlled reaction with oxygen or chlorine. The alkanes are inert to attack by most chemical reagents and will react with oxygen and halogens only under the special conditions of radical initiated reactions. 

However redox reactions of alkanes, in particular with oxygen and the halogens, are possible as the carbon atoms are in a strongly reduced condition in the case of methane, the lowest possible oxidation state for carbon (-4) is reached. Reaction with oxygen leads to combustion without any smoke with halogens, substitution. In addition, alkanes have been shown to interact with, and bind to, certain transition metal complexes. 

Hydrocarbons (HCs) from C2 to CIO are commonly used to test activity. The efficiency of the HC in the SCR of NOx in competition with the combustion reaction with oxygen increases with increasing molecular weight. This is probably due to the parallel increase in the heat of adsorption and decrease in the C-H bond strength.132 Alkanes, alkenes and oxygenated HCs have been studied in this reaction and the activity in the NOx elimination frequently follows this order, with the lower light-off temperatures being displayed for the latter type of compounds. Independent of the nature of... 

Alkanes do react with chlorine (CI2) or bromine (Br2> to form alkyl chlorides or alkyl bromides. These halogenation reactions take place only at high temperatures or in the presence of light (symbolized by hv). They are the only reactions that alkanes undergo—with the exception of combustion, a reaction with oxygen that takes place at high temperatures and converts alkanes to carbon dioxide and water. 

In order to compare the stability of constitutional isomers, we look at the heat liberated when they each undergo combustion. For an alkane, combustion describes a reaction in which the alkane reacts with oxygen to produce CO2 and water. Consider the following example ... 

HCFCs (Sect. 11.8) Hydrochlorofluorocarbons. Compounds that are similar in structure to CFCs but also possess at least one C—H bond, heat of combustion (Sect. 4.4) The heat given off during a reaction in which an alkane reacts with oxygen to produce CO2 and water, heat of reaction (Sect. 6.1) The heat given off during a reaction. 

Halogenation and combustion (burning) are the oidy reactions that alkanes undergo (without the assistance of a metal catalyst). In a combustion reaction, alkanes react with oxygen at high temperatures to form carbon dioxide and water. 

Saturated hydrocarbons have little affinity for most chemical reactants. They are nonpolar substances that are insoluble in water and unreactive toward acids, bases, or oxidizing agents. The most commonly encountered reaction of alkanes is with oxygen. Alkanes burn the oxidation of hydrocarbons underlies their important use as fuels. For example, octane reacts with oxygen as follows ... 

As we have just seen the reaction of alkanes with oxygen to give carbon dioxide and water IS called combustion A more fundamental classification of reaction types places it m the oxidation—reduction category To understand why let s review some principles of oxidation-reduction beginning with the oxidation number (also known as oxidation state)... 

The important hydrocarbon classes are alkanes, alkenes, aromatics, and oxygenates. The first three classes are generally released to the atmosphere, whereas the fourth class, the oxygenates, is generally formed in the atmosphere. Propene will be used to illustrate the types of reactions that take place with alkenes. Propene reactions are initiated by a chemical reaction of OH or O3 with the carbon-carbon double bond. The chemical steps that follow result in the formation of free radicals of several different types which can undergo reaction with O2, NO, SO2, and NO2 to promote the formation of photochemical smog products. 

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