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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: neobenzene on March 01, 2012, 10:01:04 AM

Title: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 10:01:04 AM
Hi...I'm stumped at how to convert propene to 2,3-dimethyl butane. Any help would be gladly appreciated!
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 10:04:37 AM
Hi...I'm stumped at how to convert propene to 2,3-dimethyl butane. Any help would be gladly appreciated!

Why don't you tell us what ideas you have. Then we may be able to put you on track.
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 10:10:58 AM

Why don't you tell us what ideas you have. Then we may be able to put you on track.

I'm guessing we need to convert propene to an alkane first. So, I guessing we need to do hydrogenation in the presence of nickel or palladium. That will give us propane. After that, I'm not sure.
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 10:30:08 AM

Why don't you tell us what ideas you have. Then we may be able to put you on track.

I'm guessing we need to convert propene to an alkane first. So, I guessing we need to do hydrogenation in the presence of nickel or palladium. That will give us propane. After that, I'm not sure.

Here are your two molecules, are you sure you are starting with propene?
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 10:31:34 AM
Yes...I'm sure I'm starting with propene.
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 10:43:58 AM
Yes...I'm sure I'm starting with propene.

OK, so you need to add 3 methyl groups, any ideas how this may be accomplished?
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 10:46:31 AM
Absolutely no idea. Is there anything wrong with the method that I suggested earlier?
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 10:53:40 AM
Absolutely no idea. Is there anything wrong with the method that I suggested earlier?

If you hydrogenate the double bond you will get a relatively (chemically) inert compound, propane. Better to keep the C=C and use it to elaborate the system toward your target.
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 11:06:32 AM

If you hydrogenate the double bond you will get a relatively (chemically) inert compound, propane. Better to keep the C=C and use it to elaborate the system toward your target.


Ok...if I choose not to hydrogenate it...how should I proceed? How should I add three methyl groups?

Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 11:11:04 AM

If you hydrogenate the double bond you will get a relatively (chemically) inert compound, propane. Better to keep the C=C and use it to elaborate the system toward your target.


Ok...if I choose not to hydrogenate it...how should I proceed? How should I add three methyl groups?



Do you know any of the typical reactions of a C=C?
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 11:19:33 AM

Do you know any of the typical reactions of a C=C?

Alkenes undergo hydrohalogenation. So, for example, if we treat CH3-CH=CH2 with HCl, we will get
CH3-CHCl-CH3, (by Markovnikov's rule), which is 2-chloro propane.
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 11:22:42 AM

Do you know any of the typical reactions of a C=C?

Alkenes undergo hydrohalogenation. So, for example, if we treat CH3-CH=CH2 with HCl, we will get
CH3-CHCl-CH3, (by Markvnikov's rule), which is 2-chloro propane.

Great answer, you are now half-way to your target, so how would you couple 2 "isopropyl groups"? Hint, it is a well known name reaction.
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 11:25:41 AM
I forget...what is isopropyl again? And can you please show me its exact structure?
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 11:29:24 AM
I forget...what is isopropyl again?

here is a drawing of isopropyl chloride
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 11:32:17 AM
Ok...so now we do Wurtz' reaction? In the presence of sodium and dry ether?
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 11:37:15 AM
Ok...so now we do Wurtz' reaction? In the presence of sodium and dry ether?

Bingo
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: neobenzene on March 01, 2012, 11:42:25 AM
Thank you very much, discodermolide! You were a fantastic guide!
Title: Re: Convert propene to 2,3 dimethyl butane?
Post by: discodermolide on March 01, 2012, 11:43:20 AM
Thank you very much, discodermolide! You were a fantastic guide!

My pleasure