Dear all:
Do anyone let me know about the procedure of N-acylation of Acetophenone Phenylhydrazone or (E)-1-phenyl-2-(1-phenylethylidene)hydrazine using either acetic anhydride or acetyl chloride that would be simple, efficient and optimum yield of the acylated hydrazone.
I answered a similar question already here: To 1 eq of hydrazone: DCM as solvent, 1 eq Et3N, 1.1 eq Ac2O and DMAP as catalyst (20 mol)%, RT monitoring by TLC, detection by UV or ninhydrin reagent and heat.
Yes Dr. Pavel Pazdera:
Thank you, you have answered earlier for Benzaldehyde hydrazone regarding this procedure that contains a primary amine group & as well as secondary nitrogen atom in its structure.
I hope after completion of the reaction, the reaction mixture need to be extracted with DCM and the combined organic layers need to dried & vacuum dried.....?
Dr. Pavel Pazdera:
I thought to ask you earlier itself for a small change in the above said process for acylation of hydrazone:
Following is my query:
"In the above process we are using Ac2O as an acylating agent, but the hydrazone is having a secondary amine group (R-NH-R), so with Ac2O we need a catalyst for efficient acylation, so I think we need DMAP as catalyst to run the reaction at faster pace.
Now I would like to ask you, instead of using Ac2O + DMAP, could we use CH3COCl alone (as no aqueous solvents are using) to carry out the reaction as the acetyl chloride is reactive when compared to Ac2O, so we can skip the use of the DMAP catalyst."
Kindly add your views & suggestions on the above.
Thanks & Regards,
Nagendra Babu M.
Mennuru,
Do the reaction under the condition you want to, work it out , purify and identify your product(s).
Here is some literature on v. similar structure
--- Suvorov, N. N. et alFrom Zhurnal Obshchei Khimii, 28, 1090-7; 1958
using Ac2O and p-toluenesulfonic acid cat.
---- By Schantl, Joachim G. and Gstach, HubertFrom Monatshefte fuer Chemie, 116(11), 1329-43; 1985
using Ac2O, P2O5, Br2, followed by NH3
Of course different outcome products were obtained
Good luck
AcCl will generate HCl, so you'd need to add a base, and then wash out the HCl salt with an aqueous workup. The simplest procedure would be to dissolve the substate in Ac2O, and add a trace of DMAP. Strip off the volatiles when done, and you should have a fairly clean product.