[Icey_cold]

Hi everybody~

I have a qns regarding p-methoxycinnamic acid.
How can we tell from a HMR spectrum of a p-methoxycinnamic acid has a trans configuration?

Appreciate if someone could enlightened me.

[discodermolide]

examine the size of the coupling constants, usually small (<8Hz) are cis, large (>9 - upwards Hz) are trans.

[Icey_cold]

but I was given that the pair of doublet is centred at 6.4 ppm and 7.6 ppm. if this is the case, is there any way to prove that the product has trans or cis configuration?

Please advice.

[discodermolide]

but I was given that the pair of doublet is centred at 6.4 ppm and 7.6 ppm. if this is the case, is there any way to prove that the product has trans or cis configuration?

Please advice.

Measure the coupling constant in Hz between the peaks of the individual doublets