2-Bromo-2-methylpropionic acid 2-Bromo-2-methylpropionic acid (CAS: 2052-01-9) is a useful reagent to make synthetic intermediates. A white solid at RT, it can be prepared from the acid bromide equivalent reagent, which is known as α-Bromoisobutyryl bromide (liquid at RT) by quenching it with water.
2-Bromo-2-methylpropionic acid can be left over in a workup after doing a reaction using a slight excess of α-bromoisobutyryl bromide, it is easily removed by liquid/liquid extraction with bicarbonate added to the aqueous phase. It can be ordered from Sigma Aldrich for a low price, but it I found it had a shorter shelf life than expected, after 1 year my NMR showed a second similar compound. C-NMR is better to analyze this compound as it gives three distinct peaks, whereas its H-NMR has one good peak but observing the hydroxyl is less reliable. However, I have discovered that it is remarkable easy to kugel rohr this reagent and it should be purified by kugel rohr before use. The compound looks very white and flakey when it is pure, like grated coconut, but after 1 year it has a slight yellow colour and instead of flakes it forms large crystalline shards. It has an acrid smell to it no matter how pure it is.
2-Bromo-2-methylpropionic acid can be left over in a workup after doing a reaction using a slight excess of α-bromoisobutyryl bromide, it is easily removed by liquid/liquid extraction with bicarbonate added to the aqueous phase. It can be ordered from Sigma Aldrich for a low price, but it I found it had a shorter shelf life than expected, after 1 year my NMR showed a second similar compound. C-NMR is better to analyze this compound as it gives three distinct peaks, whereas its H-NMR has one good peak but observing the hydroxyl is less reliable. However, I have discovered that it is remarkable easy to kugel rohr this reagent and it should be purified by kugel rohr before use. The compound looks very white and flakey when it is pure, like grated coconut, but after 1 year it has a slight yellow colour and instead of flakes it forms large crystalline shards. It has an acrid smell to it no matter how pure it is.
2-Amino-2-methylpropionic acid and 2-nitro-2-methylpropionic acid If 2-bromo-2-methylpropionic acid is reacted with an amine to give the amide, the bromo group can then be substituted for a nitro using a Kornblum type reaction with NaNO2 in DMF. I am still pursuing a technique to prepare the nitro equivalent of this reagent, which would be called 2-nitro-2-methylpropionic acid. The amino equivalent exists and is a kind of quasi amino acid, but the nitro version would have the advantage of not being zwitterionic which would make it a more versatile organic soluble reagent. Due to a lack of resources, this project is currently on the back burner.
