Question

Please solve the following questions regarding an carbonyl condensation reaction

2. Complete the following TLC plates by drawing what you expected in the reaction (R) column for an incomplete reaction and for a complete reaction. Consider the polarity of the product and reagents when assigning the spots and label the product spot as P next to it on the TLC. plate. A - 4-nitrobenzaldehyde B - Dimedone R - Reaction mixture -- ----- -------- A BR F-- ----- ---- --- | A BR TLC for an incomplete reaction TLC for a complete reaction

Followed by these

3. Write a summary of the major green chemistry features afforded by the synthesis. What aspect(s) of the approach taken is/are NOT especially green? What changes might be made to make the overall process greener?

4. Refer the mechanism for the reaction and point out 2 examples where proline serve as a catalyst during the reaction.

Answer 1

•TLC is one of the method for the determine whether the reaction is completed or not:

1. If the reaction is not completed it will show the spot of both reactant A and B significantly. (A= 4-Nitrobenzaldehyde, B= Domodome)

2. If the reaction is completed it will form the spot that is generally higher then both the reactants. It will not lie in between the spot of A and B.

• The reaction of 4- nitrobenzaldehyde with dimedone is knovengal condensation and michael reaction which gives 1,8-Dioxo-octahydroxanthene.

The synthesis can also be done in greener way in which it's cheap, effective, economic ,higher yield can be achieved.

The reaction lead to the formation of xanthene compound with the help of eco-friendly green Lewis acid = SmCl3 this Lewis catalyst is easily available and can be isolated easily which make this synthesis conventional.

The product that is formed have various application in medicinal(inflammation, antibacterial & antiviral) as well as in material sciences, agro , pigments and cosmetics in fluorescence too.

• Proline is an organic compounds which is chiral and use as catalyst. Proline is unique because it provides connectivity nd can be use more one one time in an reaction that provides a symmetric kind of structure. Proline use in this reaction is dimedone.

Zn(NO3)2 and SmCl3 can also be use as catalyst for the synthesis of 1,8-dioxo-octahydroxanthene.

• Mechanism of this above reaction is also attached here.

- 4- Nitrobenzaldehyde TLCA B = Dimedone R Ryon mizitore IA BR Incomplete Run Completed Rouen // Pacoline PEG-400 end Tantomerism Keto Mechanisms : Dimedone NO2 nevengels DTH NOZ + X Sme gu@m. Å ped Ho + ои