Pictures from an organic chemistry laboratory
The source of your daily dose of applied organic chemistry in pictures, directly from an organic chemistry laboratory.
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Bromination of a ketone (an acetophenone) using elemental bromine.
A bromine solution is added slowly to the solution of an acetophenone in the flask til the deep red color of the bromine persist.
If the reaction is done in the presence of a lewis acid the bromination of the aromatic ring will happen, but in absence of any lewis acidic catalyst the aliphatic carbon atom will get brominated just as in this case. It is also important to note that both bromine, both the two product of the reaction (the brominated compound and hydrogen bromide) is highly toxic.
Preparation of a phosphonium ylide for a Wittig olefination.
Triphenyl phosphonium ylides also called Wittig reagents. They are usually prepared from a phosphonium salt, and a strong base such as sodium hydroxide, potassium tert-butylate (as in this case, added on the second gif) or butyllithium.
What happenes here? This:
[Ph3P+CH2R]X− + C4H9Li → Ph3P=CHR + LiX + C4H10
The ylide (Ph3P=CHR) is often a colored compound. In my case it was deep red, almost black, as seen on the above gifs.
Separation of several fluorescent compounds by column chromatography.
Each test tube contains a different fraction of a reaction product where polyaromatic highly fluorescent compounds were made using Sonogashira coupling. It is quite interesting the from red to green/blue most color is found if we check each tube under UV light, even through an orange emitting molecule was the goal of the reaction.
Ozone (O3) is among the most powerful oxidizing agents known, far stronger than O2. It is also unstable at high concentrations, decaying to ordinary diatomic oxygen. It has a deep blue color and when it is used in organic chemistry a good indicator that the reaction is ready when the characteristic blue color of the ozone is seen in the reaction mixture.
Ozone is a quite reactive molecule, it attacks almost everything. A great example is the rubber septa at the two side neck of the flask. It was degraded by ozone during the reaction as seen.
Ozonolysis is used when we need to cleave double bonds in a molecule to get aldehydes or ketones (even carboxylic acids), just as shown here:
A quite colorful reaction mixture for Valentine’s Day.
I have performed recently a palladium catalysed oxidation and it turned out that besides it have produced at least 3 compounds, but also a highly colored minor impurity was generated from the reaction mixture that caused an intense red color. When the organic phase (deep red, in the background) was diluted it gave the above seen solution. When the solution is highly dilute, it has an intense pink color.
Someone nearby works with diazo compounds and he often obtains quite colorful compounds, just as the one seen above.
During the purification process removal of side products is quite amazing, since every product of the reaction had a different color. By removing each unwanted product from the reaction mixture, a different colored phase is obtained.
I’ve been preparing this compound for more than a month for now. It was purified and it gave 99% pure product and surprisingly it crystallized upon standing. According to the literature this compound was described everywhere as an oil, so it was quite a good moment when the above seen crystals appeared at the bottom of the flask.
On left there is a reaction that is stirred on a magnetic stirrer and kept under a slight over pressure of nitrogen gas to keep the reaction oxygen free. From the other side a quite old, but still perfectly working syringe pump is used to add a reagent to the reaction with a really low speed.
This technique is frequently used when low concentration matters and it is critical to keep at least one of reactants on a low but constant concentration.
Preparation of an aryl iodide from an aniline derivative through a diazonium salt.
The reaction scheme is this:
This reaction is quite messy, it produces a lot side products. The progression of the reaction could be easily observed, since nitrogen evolves that could be observed using a gas bubbler (first pics). A side product of the reaction is iodine that /in this case/ sublimed to the neck of the flask as seen on the second picture. With a few simple tricks, including treatment with thiosulfate
to decompose the produced iodine and filtration through a pad of silica to remove tarry side products, nearly pure product could be obtained.
Performing reactions on small scale, on low temperature (in this case
−78.5 °C , (194.65 K; −109.3 °F) using a Dry ice/acetone cooling bath.
The reactions were performed to check which base is the ideal for an organic transformation. And just as usual, 1 from the 3 reaction gave the product, and in even this reaction a low yield was obtained. But at least now we know that the transformation could be performed, since it was not yet described anywhere.
