Dear RG users, I have few questions regarding the Schiff base reactions. I am trying to carry out the Schiff base reactions to move for the synthesis of the metal complexes. As on carrying out the Schiff base reactions (with the addtion of acetic acid) colour change is noticed but I am not getting the precipitate. I have tried pouring the cold water so as to get the precipitate, but didn't the get the precipitate. Can you suggest me what can be done, as I want the single crystals of them and also to move for carrying out the metal complexes using the Schiff base. With regards,
Chethan
Dear Chethan B S in order to give you a more detailed and qualified answer, it would be useful to know a few more details. Did you follow a literature procedure to prepare your Schiff base? If yes, could you please provide the reference and a few more details? Then it would be easier to judged from the distance what perhaps went wrong. For more information you can also search RG for the term "Schiff base synthesis". This will display very many publications and also RG threads on this topic. A potentially useful article is e.g. this one entitled "Schiff base synthesis by unconventional route: An innovative green approach". This paper is available as public full text on RG (see link cited below). However, as I said, for more specific advice it would be helpful f you provided a few more details.
Article Schiff base synthesis by unconventional route: An innovative...
Thank you Frank T. Edelmann for the article, I will look into it.
I am attaching the reference article, I have followed the procedure (page number 119) as mentioned in it.
I am trying to the Schiff base reaction between 2-amino 5-mercapto 1,3,4 thiadiazole and 2-hydroxy benzaldehyde.
Dear Chethan B S many thanks for the detailed information. Did you check the progress of the reaction by TLC? In any case I think that the description of the procedure is somewhat misleading. The authors don't mention that the Schiff base product forms a precipitate. Thus I would assume that after the reaction (8-9 hours at reflux) everything stays in solution. What I would suggest is to evaporate the reaction mixture to a small volume until some solid product becomes visible. Then you can put the mixture in the freezer overnight to complete the crystallization. You can also evaporate everything to dryness, redissolve the residue in a small amount of hot ethanol and let it cool down to room temperature or in the freezer. That's what they mean by recrystallization from ethanol. Good luck!
Dear Chethan B S P.S. Here is a closely related article entitled "Synthesis, Characterization, Antioxidant Activity and Antitumor of Some 2-Amino-5-(3-nitro-phenyl)-1,3,4- thiadiazole Derivatives". The paper is available as public full text on RG. In this case it is indeed reported that the Schiff base product forms a precipitate. In any case I would not add water to the reaction mixture.
Article Synthesis, Characterization, Antioxidant Activity and Antitu...
Thank you @Frank T. Edelmann for your suggestions and the useful articles.
However, in few literature they mention the addition of the sulphuric acid in the place of acetic acid, does it plays a crucial role? In some papers they will add HCL to the solution until the precipitate seperates out. In which cases do we have to follow these steps? Can it be used as a general procedure for the synthesis of Schiff base?
Dear Chethan B S I would suggest to follow the literature that really describes your specific products containing thiadiazole moieties. Of course it might be worth a try to use a few drops of sulfuric acid instead of acetic acid. It's just important that you employ some acid as catalyst. Besides, it's difficult to give a general advice because there have been countless Schiff base derivatives reported in the literature. Just try any variant on a small scale first to see if it works. In this case an orientating experiment is worth more than thousand words.
Thank you Frank T. Edelmann for all the suggestions sir, I will work on with it.
With regards,
Chethan
Dear Chethan B S you're welcome. I hope it works. If you have any further questions, please feel free to ask again.
Just one minor point: When someone answers your questions on RG and you find the answers helpful, it is a good habit on this platform to recommend those answers.
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