You can detect whether the ester bond has formed or not by taking IR whether IR sr. band is observed above 1720 cm-1 wave number or /by taking 1H NMR  & CMR and looking at the position of the signals.

You can use FT-IR or 13CNMR.

Dear all,

you can follow the consumption of any of the functional groups with time by titration, or also follow the amount of water formation. Regards

IR can be a good option, so 13C NMR

 Dear All,

Thank you so much for the kind feedback! Much appreciated!

Cheers

On the basis of the 1H NMR, 13C NMR and FT-IR data, you can detect whether the ester bond has formed or not. The FT-IR spectra showed a band at 1700 cm-1 wave number which correspond to C=O or using NMR which give you structural identification and the positon of acylation. You can also use TLC analysis (thin layer chromatography) you can see the presence of new spot which correspond to new compound.