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Figure 6:Reaction Coordinate Diagrams showing reactions with 0, 1 and 2 intermediates: The double-headed arrow shows the first, second and third step in each reaction coordinate diagram. In all three of these reactions the first step is the slow step because the activation energy from the reactants to the transition state is the highest.
The reaction is used for the transfer of methyl and ethyl groups between benzene rings. This is of particular value in the petrochemical industry [1] to manufacture p-xylene, styrene, [2] and other aromatic compounds. Motivation for using transalkylation reactions is based on a difference in production and demand for benzene, toluene, and xylenes.
In chemistry, a reaction step of a chemical reaction is defined as: "An elementary reaction, constituting one of the stages of a stepwise reaction in which a reaction intermediate (or, for the first step, the reactants) is converted into the next reaction intermediate (or, for the last step, the products) in the sequence of intermediates between reactants and products". [1]
The first C–H activation reaction is often attributed to Otto Dimroth, who in 1902, reported that benzene reacted with mercury(II) acetate (See: organomercury). Many electrophilic metal centers undergo this Friedel-Crafts-like reaction. Joseph Chatt observed the addition of C-H bonds of naphthalene by Ru(0) complexes. [3]
A side reaction is hydrogenolysis, which produces light hydrocarbons of lower value, such as methane, ethane, propane and butanes. Continuous Catalytic reforming (CCR) unit In addition to a gasoline blending stock, reformate is the main source of aromatic bulk chemicals such as benzene , toluene , xylene and ethylbenzene , which have diverse ...
An alkyne trimerisation is a [2+2+2] cycloaddition reaction in which three alkyne units (C≡C) react to form a benzene ring. The reaction requires a metal catalyst. The process is of historic interest as well as being applicable to organic synthesis. [1] Being a cycloaddition reaction, it has high atom economy.
Steam cracker process diagram Gibbs free energy per carbon atom. This shows that at high temperature, hexane can split into ethane and ethylene ("Ethen"), and ethane can split into ethylene and hydrogen. But ethylene can decompose into methane and carbon if given too much time, and all the hydrocarbons can decompose into carbon and hydrogen.
The products produced in the reaction depend on the composition of the feed, the hydrocarbon-to-steam ratio, and on the cracking temperature and furnace residence time. Light hydrocarbon feeds such as ethane, LPGs or light naphtha give product streams rich in the lighter alkenes, including ethylene, propylene, and butadiene.