Week 11: “Vanillin Synthesis from 4-Hydroxybenzaldehyde”

Source(s): This lab was developed by a team of students from a recent JCE article: Vanillin Synthesis from 4-Hydroxybenzaldehyde.” Douglass F. Taber, Shweta Patel, Travis M. Hambleton, and Emma E. Winkel, J. Chem. Educ. 2007, 84, 1158. An online version of the lab was available at http://valhalla.chem.udel.edu/vanillin.pdf

Changes to published procedure
We scaled up the procedure – Part I 0.5g 4-hydroxybenzaldehyde.
The product from Part I (3-bromo-4-hydroxybenzaldehyde) was isolated by liquid-liquid separation and solvent evaporation.All of the product from Part I was used for Part II.We used boiling water baths to heat the reaction for Part II.
We did not do the column chromatography step.
We performed a GC-FID of the products from both Part I and Part II.

Positive
+ A little more challenging procedure – a nice fit for late 2nd semester.
+ The product smells nice – olfactory confirmation of a successful synthesis.

Neutral

± It is very difficult to distinguish between 4-hydroxybenzaldehyde, 3-bromo-4-hydroxybenzaldehyde, and vanillin by TLC.
± Our GC did not distinguish between 3-bromo-4-hydroxybenzaldehyde, and vanillin.

Negative
– We had a hard developing this lab successfully. In hindsight, I think we failed to appreciate the need to heat the reaction in Part II to a much higher temperature than would be achieved by simple reflux conditions.
– In my opinion, working with bromine and ethyl ether should be avoided whenever possible.

Inquiry & Extension ideas.
● Could be part of an exploration of an Electrophilic/Nucleophilic Aromatic Substitution study.

Advertisements

One Comment

  1. Ricardo Rodriguez
    Posted April 30, 2008 at 9:08 pm | Permalink

    I would probably suggest heating the reactants to at least 175 C. Although there runs the risk of evaporation to dryness of the sample is not kept an eye on, and the refluxer is not cold enough to prevent the outflow of reactants evaporating into the atmosphere.


Post a Comment

You must be logged in to post a comment.
%d bloggers like this: