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Topic: Reactions to lengthen hydrocarbon chains  (Read 6356 times)

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Offline jamaal

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Reactions to lengthen hydrocarbon chains
« on: February 11, 2008, 01:44:49 PM »
Hey I was wondering if there are any direct one or two step reactions which could be used to lengthen the carbon backbone of a molecule such as butane to octane, or ethylbenzene to butyybenzene.  I know of one method which would utilize a lot of steps and it doesn't seem feasible to me (too many steps).  I was thinking for example if you were to use butane in a radical reaction with chlorine you'd obtain a mixture of products of  1-chlorobutane and 2-chlorobutane.  Then with 1-chlorobutane you add magnesium in THF, to get a grignard reagent.  With the grignard you'd react it with acetone in dilute acid to get the alcohol.  Then with the alcohol you'd react that with a reagent such as sulfuric acid to make an alkene via elimination.  Finally with the alkene you'd hydrogenate it in a nickel or platinum catalyst to furnish your new alkane that is longer. 

Offline minimal

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Re: Reactions to lengthen hydrocarbon chains
« Reply #1 on: February 11, 2008, 01:54:54 PM »
Am I to understand that you want to use chemicals that are easily obtained?  Afaik the starting point is the halogenation of alkane to an alkyl halide.  From there though you don't have to go through as many steps as you did before, (http://en.wikipedia.org/wiki/Coupling_reaction).  Lots of those involve alkyl or aryl halides, although palladium is used as a catalyst in most of them. 

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