I was looking more into the lines of trying to consume the water during the chemical reaction and not post reaction..

Depending on the solvent you are using, I have frequently added powdered anhydrous MgSO4 or Na2SO4. That has helped me out with several stubborn imine formations and esterifications.

Thanks. I was thinking in the same lines too, but it is making my reaction mixture viscous

did you test to add so molecular sieves ?

If you are doing reaction at high temperature, use Dean-Stark for removal of water.

@Christel- Yes, I did. But want to use something else.

@Tanaji- Yes, I have done that but then it traps my solvent too.

You can put molecular sieves in the cup of a Soxhlet extractor, and run the solvent reflux through it. This has the advantage that your azeotrope doesn't need to be a two-phase system - it works with ethanol, for example.

Because this method doesn't mechanically abrade the sieves, you can bake them in an oven and re-use them, which is about as green as you can get. If you still don't want to use sieves, any other dehydrating agent that's compatible with the solvent can be used. MgSO4 would be a typical second choice, and like mol. sieves it's re-usable after baking.

Keep in mind that energy is not free, and that a typical vacuum oven is hugely inefficient. On a laboratory scale, mol. sieves are worth recycling, but MgSO4 might best be sent down the drain.

Thank you, I will try this on Monday. I like this idea very much. Thanks.

Molecular sieves (3A or 4A) or DST can be used for this purpose.

An alternative strategy is to run your reaction in pentane. Water will partition out very effectively and thus, by Le Charlie's

Principle, favored product formation while sequestering the water formed during the reaction.

If you use non polar solvent , you can use dean- stark to isolate water from reaction mixture

This is only effective if the solvent has a higher boiling point than water (eg toluene). In the case of pentane I don't think Dean Stark would be an option. I'm mentioning pentane because it is particularly effective at partitioning water (more so than toluene) and in the case of the esterification of boronic acids, for example, demonstrates huge advantages over options such as Dean stark or physical desiccants such as mole sieves (eg 2 hour reaction time resulting in quantitative yield of MeBpin relative to the literature procedure which requires >24 hour using diethyl ether and desiccants).

Using desiccator agent like MgSO4 or NA2SO4 and better to use molecular sieve more

Or Using a dean stark where Toluene is the solvent!!

Dear Dr. Karamé, I don't believe Maria Dollar specified that toluene is the solvent being used. Is there a reason you are using exclamation marks? Also both Dean Stark and MgSO4/Na2SO4 have already been suggested; Dr. Demers proposed a particularly promising option.

Thank you all for your suggestions, I really appreciate it.

To stop water molecules generated as a byproduct in an Organic Synthesismaintain the reaction conditions, pure starting material, catalst conc., mole ratio & temperature properly to avoid the formation of the side reaction products. If necesary use protecting groups to prevent unwanted chemical transformations.

Dean stark if the Toluen can be used as solvent, otherwise using molecular sieves seems to be the most adequate

To stop water molecules generated as a byproduct in an Organic Synthesis use dehydrating agents like p-toluene sulfonic acid or carry out the reaction in DCC. Otherwise remove water by using azeotrope with benzene using Dean-Stark apparatus.

Benzene is very toxic!! carcinogenic compound,

Toluene is acceptable alternative

Say - have you thought of using a Dean-Stark trap? :-)

Seriously, Gabriel's suggestion (pentane) does work, provided that the reactants are sufficiently (even if not entirely) soluble, and that the activation energy of the reaction doesn't make heating necessary. Phase separation, alone, can drive a dehydration reaction to completion, and it could be sufficient to minimize water-induced side reactions as well. (The aqueous phase acts as the "drying agent" for the pentane solution.)

Hexane should work just as well; I think, if you keep it at room temperature. It's worth trying, just for the sheer simplicity of the method.

For sure, Dean-Stark trap is a good option for physically separating water from reaction, alternative to molecular sieves. Another good option is using DCC to chemically remove water, like Madhukar suggested. In this case, the urea should crystallize out of the reaction.

You can use triethyl orthoacetate during your reaction as a water scavenger but I believe it is easy to decompose and produce acetate depending on reaction conditions