I tried a lote of reaction with various aldehydes and 2-amino-4-methyl benzothiazole. But I didn't get the exact product. I followed oil bath condensation procedure. Why I can't get the product? How I rectify my default? I added catalyst too.. but product exactly same as the starting amine. Please help me a suggestion
Dear Anjali Krishna G, from the outside it is difficult to judge what the problem is without knowing which literature procedure you followed. Normally the starting materials (2-amino-4-methyl benzothiazole + aldehyde) are refluxed in methanol or ethanol for a few hours. There are a number of references available on RG such as the ones cited below. Please also find attached two more references as pdfs.
Article Antibacterial Co(II) and Ni(II) complexes of benzothiazole-d...
Article Synthesis, Spectroscopic Studies, and Biological Activity of...
Dear all, I would suggest to check the purity of the reactants, use freshly purifier ones. Attached is an interesting document. My Regards
Also use a water absorbing agent, such as MgSO4, or equivalent. good luck.
Dear Anjali;
To successfully complete this synthesis, it is necessary:
1- First, make sure that the starting reagents and solvents are of analytical grade;
2- The glassware used must be washed beforehand with methanol or ethanol.
3- The use of microwaves instead of conventional heating in order to have rapid and homogeneous heating of the reaction medium. This heating technique also improves the yield of the reactions and reduces the formation of side products
4- Conventional heating syntheses allow obtaining Schiff bases with good yields, but too important reaction times (up to 24 hours) as well as condensation, purification and filtration steps are required.
5- The condensation step is very important for the success of the synthesis. It is interesting to use azeotropic distillation to shift the balance in the direction of schiff base formation.
With my best regards
You can add 2 or 3 drops of dry acetic acid and reflux for a longer time. Also, start with aldehyde and not ketone.
Krishna
Here is a reported method very similar to yours
It is clear that you need a reagent that absorbs water from the reaction media
***Frias, Maria et al Chemistry - A European Journal, 24(13), 3117-3121; 2018
Good luck
It is possible possible for obtaining the Schiff bases using 2-amino-4-methyl benzothiazole .Take 2-amino-4-methyl benzothiazole in ethanol , add aryl aldehyde and 2-3 drops of acetic acids. Then reflux the reaction mixture on water bath till solid separates in the reaction flask.
Thank you all for your valuable replies..it's all a very releif to me..Thqnks a lot
Ms. Anjali, you are well tried. My suggestion is better to check the purity of chemicals first. Plenty of reports available on these type of reactions mostly by the simple condensation between aldehyde and amine in aprotic or protic solvents without any catalysts at room temperature or at reflux condition. Sometimes catalytic amount of acid catalysts like acetic acid or p-toluene sulfonic acid etc., were used. In some other cases dehydrating agents such as molecular sieves were used to prevent the back reaction. So, have continuous monitor on formation of any new spots over TLC (in certain cases they may revert back) and sometimes you should be cautious in work-up too.
I fully agree with M Venkata Krishna Reddy in that addition of a catalytic amount of acid (acetic acid, sulfuric acid pr p-toluene sulfonic acid) copuld be very helpful in this case.
I think your TLC or Analytical system needs to be developed.sometime it happen that reaction goes but due to improper TLC system. it is difficult to find out product formation due to very close rf values of reactant and product in that particular TLC system. So try to develop proper TLC system.