I need help how to do trituration procedure and blue colored question ! thanks i

Question

I need help how to do trituration procedure and blue colored question !

thanks

iltration. Ifthe less soluble component of the mixture is desired, the solid is retained. Ifthe more soluble is desired, Ihe filtrate is concentrated to dryness. To find sucha solvent, one can test the solubilities of benzoin (that you made) and benzil (authentic) in some common lab solvents using TLC It is very important that the benil (IV-02) obtained in this step is free from benzoin (I 01) before conducting the next step in the synthetic sequence. Besides TLC, one can check to see if the product is free of benzoin using this qualitative test (it is more sensitive than TLC): To ca. 0.5 mg of your product, add 0.5 mL of 95% ethanol or methanol and add one drop of 10% NaOH If benzoin is present, a purple color will form. This color comes fron a complex that forms between benzil and the auto oxidation product of benzoin). If you obtain a positive result, you will need to re-purify your material again until the test is negative. If you do not observe a purple color, add 0.5 mg of benzoin to see what a positive result would look like What reasons can you think of for the importance of having the benzyl free of benzoin? Think about the next step in the sequence.

Explanation / Answer

Synthesis of Benzyl from Benzoin can be done by simple titration procedure.

1. First take 0.5 mg of your product in conical flask or beaker.

2. Add 0.5 ml of 95% ethanol or methanol in it.

3. Prepare 10% NaOH solution and add one drop of 10% NaOH solution in above mixture. The NaOH help to search HCL form as a side product in the reaction.

4. If benzoin is present a bluish purple colour will form. Purple colour comes from the complex form by oxidation of bezyl and benzoin.

5. To remove purple colour that means to remove benzyl completely you need to repurify the substance. In repurification you have to reflux the solution for 15-20 min.

6. Remove the solution and cool it in ice bath. Crystallization takes place.

7. Filter the substance through vaccume filter and then wash with ethanol to dissolve the crystals. Repurification is done to purify the product from other impurities.

8. Continue washing with ethanol until the blue purple colour disappears. (colour disappers means test is negative.)

7. If no purple colour then you can say that product is free from benzoin.

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