# The synthesis of 1-phenylprop-1-ene from propiophenone [closed]

I would like to know how to make 1-phenylprop-1-ene ($$\ce{C6H5-CH=CH-CH3}$$) from propiophenone ($$\ce{C6H5-CO-CH2-CH3}$$)?

I think carbonyl group ($$\ce{C=O}$$) of propiophenone is electron-withdrawing group because of Oxygen of carbonyl group. So the carbonyl group of propiophenone will be attacked by nucleophile. And this will be oxidized to make double bonds.

But I don’t know the detail reaction mechanism to make phenylprop-1-ene from propiophenone.
Can anyone help me understand this reaction mechanism?

• A detailed reaction mechanism is an orthogonal question to a synthetic route. At the very least, you are confused about what kind of answer you need for this problem. (It's probably not a mechanism, though that may be helpful.)
– Zhe
Jul 27, 2019 at 17:32
• Your suggested synthetic rought is not going to happen. Thus, can't suggest a mechanism. Yet, the best way to do this is given in Waylander's answer. I think you should accept that answer because it is best way to do this transformation. Jul 28, 2019 at 3:13
• I think I should ask a synthetic route, too as you teach me. I didn't understand the exact meaning of reaction mechanism.
– Jan
Jul 28, 2019 at 15:15

Step 1 - reduce the carbonyl group to a secondary alcohol. Sodium borohydride in $$\ce{MeOH}$$ or $$\ce{EtOH}$$ will do this in high yield and the workup is straightforward.
Step 2 - dehydrate the secondary alcohol to give the double bond. As it is a benzylic alcohol, protonation of the $$\ce{-OH}$$ group and formation of the benzylic cation is strongly favoured and will give you the alkene you want. Catalytic para-toluenesulfonic acid in refluxing toluene (with water removal by Dean-Stark apparatus) will do this easily.