reaction using lithium aluminum hydride

[TimeforDAT]

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CH3COCH2CH=CH2

1. LAH/Ether
2. H20, H+

answer comes out to CH3CH(OH)CH2CH=CH2

can someone explain the mechanism to how you get this?

I'm sure that LAH donates the hydride to the carbonyl oxygen, so thats where the OH comes from right? So what does the H20, H+ do?

 

[KEC029]

doesn't H- from LAH make o= to o- and h2o/h+ provide H for o- ?

so i think

CH3COCH3 + LAH -> CH3CH(O-)CH3 + H2O/H+ - > CH3CH(OH)CH3

someone correct me if it's wrong.

 

[TimeforDAT]

doesn't H- from LAH make o= to o- and h2o/h+ provide H for o- ?

so i think

CH3COCH3 + LAH -> CH3CH(O-)CH3 + H2O/H+ - > CH3CH(OH)CH3

someone correct me if it's wrong.

thanks Kec, i read a little more and that's what it seems like it is doing.

 

[Joey413]

First, its Li+[AlH4 -] ---Lithium aluminum Hydride. You have to understand that the hydrogens here carry one full negative charge(1-). So the electrons between the Al and H (Al---H) travel to the partial positive carbonyl carbon due to opposite charge attraction. Why they attract? because of oxygen's inductive powers which draw electrons away from the carbon, causing a partial positive site on the carbon so..once the electrons of the hydride land on the carbon, the carbon has more than four bonds, so you must break a weak bond in our case it will be the pi bond between the carbon and oxygen, and so the electrons from the pi bond will move to the oxygen giving it a negative one charge(1-). Now since the oxygen is negative it needs to be stablized, so you can add a hydrogen which can come from water..so again electrons will travel from the negative oxygen to the partial positive hydrogen of the water.. and you have ur product..