What is the Product of the Organic Reaction?

[JDK]

Hello,

I came across this quetion...

Complete and balance the following reactions:

            OH
             |
CH3-CH2-CH2-CH-CH3 ->

Now, I don't know if I've gone crazy or something, but what's supposed to happen to that? Its a simple alcohol (2-pentanol) standing there all on its own. I don't have the foggiest what I'm supposed to do to it. I just finished a bunch of work on amides, amines, and polymers and suddenly there's these types of questions. Some are obvious and some... are not. Like this one for example. If anyone could shed some light upon this frustrated mind I'd be grateful. Thanks. [b(]

 

[FZ+]

Does it give you any other clues at all? Like reagents? A final product? Is it part of a larger question?

 

[GCT]

The alcohol can dehydrate if heat is applied.

If the molecule was supposed to be an aldol then condensation could occur.

Also think of what might happen if two of the alcohols reacted with each other.

 

[JDK]

Thanks everyone. With your suggestions I eventually determined, in relation to what the assigned reading was for the Unit, that the reaction they were "implying" to happen was an elimination reaction like this...

            OH               H H H
             |      acid     | | |
CH3-CH2-CH2-CH-CH3  ---->  H-C-C-C-C=C-H 
                             | | | | |
                             H H H H H

2-pentanol                 1-pentene

I do believe that is correct. But, please let me know if I'm wrong.
:)

 

[GCT]

Think markinakov reaction. You have an antimakinovkov product, which is incorrect. Forgot the spelling of his name.

 

[eagleone]

Originally posted by GeneralChemTutor
Think markinakov reaction. You have an antimakinovkov product, which is incorrect. Forgot the spelling of his name.

makinovkov
I’m pretty sure it’s Markovnikov.
Yap = will be on less substituted atom..

 

[FZ+]

And since it asks you be balance the equation, you want to include the H2O product on the right hand side.

 

[garytse86]

I thought you are most likely to get the product with hydrogen to the carbon with the most hydrogen (Markovnikov's rule), i.e. most abundant, but the product GeneralChemTutor suggested the product was incorrect. Please correct me if I am wrong.

Gary

 

[KLscilevothma]

Originally posted by JDK
Thanks everyone. With your suggestions I eventually determined, in relation to what the assigned reading was for the Unit, that the reaction they were "implying" to happen was an elimination reaction like this...

            OH               H H H
             |      acid     | | |
CH3-CH2-CH2-CH-CH3  ---->  H-C-C-C-C=C-H 
                             | | | | |
                             H H H H H

2-pentanol                 1-pentene

I do believe that is correct. But, please let me know if I'm wrong.
:)

I think most acids can't trigger the above reaction. Concentrated sulphuric acid is one of those which can. Also, heat is required.

 

[garytse86]

what determines whether the acid can trigger the reaction or not?

 

[KLscilevothma]

Originally posted by garytse86
what determines whether the acid can trigger the reaction or not?

I may be wrong, but I think it is because concentrated sulphuric acid is a dehydrating agent, so it can eliminate H₂O. I think the key point is whether it is a strong dehydrating agent or not.

 

[garytse86]

but how come a dehydrating agent can create a product not following Markovnikov's rule?

 

[GCT]

The deyhydration product which is the most substituted will be the major product since it has the most electron donating groups to stabilize the intermediate carbocation.

The reaction proceeds through a protonated alcohol, this converts the hydroxy group to a good leaving group.

 

[Chemicalsuperfreak]

OK, so Markownikoff's (it's russian name, there is no 'proper' spelling in the english alphabet) Rule has to do with the addition of hydrogen halides to double bonds.

We're dealing with elimination so we use Saytseff's or Hoffman's Rule. This is an E1 elimination, so we get the more substituted double bond due to hyperconjugation, it is also the more thermodynamically favored product.