Monday, May 23, 2011

Monday

Actually the TLC was conducted today, which showed that there was no reaction occuring at all.

So my advisor gave me a new project. Also product synthesis. But this time, there will be two synthesis of products.

First is the Prenylation of aromatic aldehyde.

Second is the synthesis of chalcone from the prenylation product and aromatic ketone via aldol condensation.

Which means I have to synthesize one of the reagent for the second synthesis. I'm thrilled, because I like synthesis, because chemical reactions are at play here, but the first reaction takes 48 hours to yield some amount of products, so, I'm not really happy having to waste time waiting.

Anyway, to the first synthesis:

The first synthesis required 3-hydroxy-4-methoxybenzaldehyde (1g) which i dissolved in 12ml of 10% KOH solution (self-prepared), which turned the mixture transparent yellow.

Weighing 1-bromo-2-methyl-but-2-ene (Reactant 2, simplified: PrBr) was a [roblem. PrBr exists in liquid, and is both photosensitive and sensitive to air. And also flammable and corrosive.

Since I definitely could not use a transparent container to place in PrBr, so I took a glass vial with a stopper, wrapped it with aluminium foil to use as a container.

As I transfered the amount I needed, my eyes gradually became incredibly painful, (which was the exact same pain I remembered as I prepared wasabi paste from wasabi powder in my japanese restaurant working days) and I tried my best not to inhale in the halogen-ish smell.

So yes, I considered weighing in a fume hood, but there were no weighing scales in the fume chambers. So I just had to bear it through.

Then the PrBr was added drop by drop into the round bottom flask containing the yellow solution of R1 and 10% KOH. Adding PrBr drop by drop made the mixture turn gradually more cloudy and the colour form yellow to reddish brown.

then the reaction mixture was stirred with magnetic stirrer.

Guess how long will I have to wait? 48 hours! Again!!

This time the yield had better be satisfactory!

But the advisor did tell us that failed synthesis is normal so I dont have to worry.

No comments:

Post a Comment