Stoichiometry Of A Chemical Reaction Lab

The progress of the reaction was monitored in my case using two TLC plate. It first started off with the spotting of Standard benzoin and benzil which were provided in the lab and followed by the addition of the reaction mixture at once it starts changing colour/boiling, then at 10 and 20 mins into the reflux. Once all the necessary steps were spotted, the TLC plate was placed in in a beaker containing CH₂Cl₂(methylene chloride), which was used as the developing solvent in this experiment. To check to see if the desired result had been produced when the TLC plate is looked under a UV light, the reaction mixture’s spot should match the spot of benzil; your desired product. In my TLC plate, there was one more spot, which indicated that there
For TLC as stated in the above paragraph if there is another spot that does not match the spot of your benzil then your product is not yet pure and is either contaminated or your reaction is not complete. Additionally, the purity of the product can also be determined using IR. In this experiment, when looking at the IR of the product, if there is a peak present an O-H bond (which is usually at 3500‐3300 cm‐1 ), then your product is not pure. In the IR that I got, you can clearly see that there is no O-H peak whatsoever, but there is a C-H stretch, C=C, and C=O stretch, which are expected, thus meaning that my product is pure. The reason you do not want to see an O=H stretch in your product’s IR is that in Benzil the bond is not present while it is present in benzoin. Hence, if this is found in your product's IR, the reaction was not
The Rf value is defined as the extent of substance traveled divided by the distance traveled by the solvent front. The Rf on the second TLC for benzoin was 0.55 cm ÷ 4.5 cm = 0.12, whilst the Rf value for benzil was 2.3 cm ÷ 4.5 cm= 0.51. From these results, one can see that benzil has a higher Rf than benzoin. This is because benzil is a less polar compound compared to benzoin. To explain further, with TLC and polarity, Rf values and polarity are inversely related. The spot with the highest Rf value is the least polar (fastest moving), and the spot with the lowest Rf value is the most polar (slowest moving). So because of the benzil travelling further when divided by the distance that the solvent travelled, the Rf of benzil will be