Question

What are the answers for these problems ? Need help ASAP !

omplete this section after the experiment is complete. ou will not run a TLC for this experiment. The TLC Analysis for the Wittig Reaction experiment is provided here. Lane 1-9-anthraldehyde Lane 2 -benzyltriphenylphosphonium chloride Lane 3 - triphenylphosphine oxide Lane 4-the crude reaction mixture Lane 5- the recrystallized product 18

Answer 1

From the given images the answers for the question no. 1,2,3,4 can be given. Other answers are totally dependent on experimental values which are not provided.

1. R_f value stands for Retention factor.

R_f=( distance travelled by the compound)/(distance travelled by solvent front)

Now using a ruler these distances can be measured. (as per the image given, please check with your original image)

For 1, R_f=(3.1 cm/6cm)= 0.52

2, R_f=(0.2cm/6cm)= 0.033

3, R_f=(0.6cm/6cm)= 0.1

4, R_f=(4.8cm/6cm)= .8

2. The movement of the compounds in TLC plate completely depends upon the polarity of the compound. TLC plates are made of silica gel supported on aluminium plate. Silica gel is a polar compund. Thus it will prefer to bind with the polar compounds and thus the polar compound will move slowly compared to the non-polar compounds. Thus, whatever the reagents have been used in this reaction are more polar than the product. Because of the less polarity of the compound it has travelled larger distance than the other compounds. This has resulted in the higher R_f value for the product.

3. The result of lane 4 tells that the reaction is not complete yet. It still has the starting materials (9- anthraldehyde, benzyltriphenylphosphine chloride and triphenyl phosphine oxide) left in the reaction mixture. Product has also formed.

4. The result of lane 5 tells that the recrystallized product is pure. There is no other spot present except the product. Thus the receystallized product is 100% pure.