[xshadow]

Why the  Fischer Esterification of trans 4-methoxycinnamic acid can decompose the compound and is not a valuable way in order to do an esterification??!


....Perhaps because  I have an α-β unsaturated carbonyl compound ??
And the H⁺ can "attack"  also the C=C ( as well as  protonate the C=O) ?

thanks

[Babcock_Hall]

Can you think of any other chemistry that might happen besides esterification?  I would focus on the catalyst (as you did), but I am not quite sure what you mean by "attack."

[xshadow]

Can you think of any other chemistry that might happen besides esterification?  I would focus on the catalyst.

the "catalyst" is the acid environment

The only thing  that comes to mind is the electrophilic addition of H⁺ to C=C....

[Babcock_Hall]

Once the proton adds to one of the carbon, is there free rotation around the C-C bond?

[xshadow]

Once the proton adds to one of the carbon, is there free rotation around the C-C bond?

When the proton adds at one carbon of C=C bond I'll get a single bond....and there could be a rotation

SO I could have a 180 degree rotation ...and after that rotation if the C=C is reformed  I'll have the cis isomer instead the trans one?
Do you mean this?

Thanks.

[Babcock_Hall]

You are on the right track, but think about chemical equilibrium.

[xshadow]

You are on the right track, but think about chemical equilibrium.

If I thought at the equilibrium between cis and trans ....the trans isomer should be more stable

[Babcock_Hall]

Yes, but there will be some fraction of of the cis-form.

[xshadow]

Yes, but there will be some fraction of of the cis-form.

Thankss!