Electrophilic+Aromatic+Iodination+of+Vanillin-Rewrite-Joe

Introduction
The purpose of this lab is to perform an electrophilic substitution reaction with an aromatic compound. This process is an EAS (electrophillic aromatic substitution), beginning by having an electrophilic reagent added to the aromatic ring. In order for the electrophilic reagent to add to the ring it must attack the double bond. This addition of an electrophile forms a carbo-cationic intermediate which eliminates the double bond. Then to reestablish the double bond and keep the stability of the ring, the Hydrogen is removed from the Carbon with the newly attached Iodine and donates its electrons to reform the double bond. Throughout the reaction, halogenation of the aromatic compound typically occurs due to a catalyst involved in quickening the reaction. Since Iodine is quite stable, it will be used in this reaction for halogenation. The aromatic compound which is used in this experiment is 4-hydroxy-3-methoxybenzaldehyde also known as vanillin.



Procedure:
Dorsee, Kenneeth M., and James E. Hutchison. Green O﻿rganic Chemistry: Strategies, tools and Laboratory Experiments. 186-188. Print.

Data:
Beginning mass of vanillin: 1.020g Beginning mass of NaI: 1.170g Rate of addition of Sodium Hypocholrate: 22drops/min Mass of Crude Product: 1.635g Amount of 2-propanol solvent: 12ml Amount of Water solvent: 10ml Experimental Melting Point: 179.3°C-182.1°C Literature M.P.: 183°C (chemexper.com) No End mass recorded due to minimal amount of recovery: Not enough to take mass

Theoretical Yield:

1.020g vanillin×(1mol/152.15g)=0.007mol×278.04g/(1mol 5-iodovanillin)=1.86g5-iodovanillin

Actual Yield--Not enough recovered product to determine.

I'm not sure when exactly things went wrong for you. This experiment typically goes without trouble for folks, although small crystals can be a bit of a challenge.

Observations:
After addition of bleach to the mixture it becam a dark brown color When HCl was added the mixture became a light yellow color Throughout the experiment there was a somewhat pleasant odor from the reactions due to the aromatic compound

Error Analysis:
-Possibly too much addition of solvent could have led to small size of crystals -Cooling of the final crystals may have went too rapidly causing very small crystals to form -Not enough mass of product was recovered to measure

Conclusion:
Electrophilic aeromatic substitution of vanillin to 5-iodovanillin is a process that requires careful steps to obtain an accurate recovery. The experiment appears to be very inefficient in the processes above. Can you speculate about when things got problematic for you? Did your product smell like vanilla? I would think it should NOT have, since the iodinated vanillin doesn't have the same odor. As for purity of the end substance it seems to be very pure according to the melting point data. The recovery of final product was only due to the very small size of crystals after recrystallization. If you look at the atom economy below for the overall reaction it appears to be fairly green considering that 94.91% of reactants are utilized in the final product.

This report earned the following scores for: format (2/2) style (2/2) data (2/3) quality of result (0.5/1) quality of reported data (0.5/1) conclusion (2/2) error (1/1) post-lab Q (2/2) for a total of 12/14.

Post-Lab Question:
Atom Economy (262.0 g/(126.144 g + 149.9 g) x 100 = 94.91%