Reaction mechanism

MiniJo

1. The problem statement, all variables and given/known data

Draw a step-by-step mechanism using curly arrows for the following transformation. You do not have to worry about stereochemistry of the final product.

2. Relevant equations

None

3. The attempt at a solution



So the reaction is shown in the diagram in the first line. Here's what I did:

1. Electrons in the O-H bond move toward the oxygen, and hydrogen gets detached, forming a negative charge on the oxygen
2. pi electrons from the double bond attack a H+ (from the acid) and forms a carbocation
3. The negative oxygen's electrons are attracted to the carbocation centre and draws the molecule into a ring formation

Does the mechanism make sense? Are there any other better ways of doing it? I know that there's another mechanism that involves the water molecule coming in, but I'm not sure about it.


Thanks

Borek

How likely is the presence of O^- if it happens in the sulfuric acid?

Borek
--
http://www.chembuddy.com
http://www.ph-meter.info

chemisttree

When I examine reaction mechanisms and am given a catalyst (like H2SO4 in this case), I try to use it in the first step. In this case H+ is the catalyst.

MiniJo

Hm... I attempted it again, using your suggestions, and here's my result.



Does that look better?

chemisttree

That's close. I wouldn't have lost the primary alcohol. If the alcohol were labelled (as O-18), the label would probably be found in the product.
Also, the sulfuric acid probably adds across the double bond in Markovnikov fashion.