I imagine you want to prepare hydrazide derivatives. For this purpose, reaction can be carried out using anhydrous methanol or ethanol. Sometime adding THF in the mixture can be useful. You can see a general procedure in "Reactions of hydrazines with esters and carboxylic acids" by Smith and al. (doi : 10.1021/jo01266a085).
Solvent be used for the reaction between ester and amine(Hydrazine) preferred solvent is methanol. However, in case of the non availability of methanol an ethanol can be used .
Previously, I used ethanol for the reaction between ester and hydrazine. Both starting materials are soluble in ethanol, meanwhile the newly formed hydrazide is not. Therefore, only by using filtration, I was able to separate the expected hydrazide.
Corentin Lefebvre Sir, yes i tried to make hydrazide derivatives and i performed reaction in both anhydrous methanol and ethanol but when i monitored TLC there was no formation of product.
Warda Rukh in my experiment, both were fine. But I preferred EtOH due to its lower overall toxicity. You can try with EtOH first. If things do not go well, then you can try MeOH.