brain drain. brain drain. LINK / CITE ADD TO WORD LIST. noun. The definition of brain drain refers to a situation where all or the majority of intelligent, skilled or capable resources within a given field or geographic region leave the area because of various factors including lack of high paying jobs.
Alkylation is an important source for octane in gasoline. Source: Occupational Safety and Health Administration. Alkylation (al-kuh-ley-shun) is a secondary refinery unit operation that many refineries in the United States have because it adds high octane hydrocarbons to motor and aviation gasoline. High octane hydrocarbons are needed to help prevent autoignition of gasoline (knocking) in an engine and to meet recommended engine octane ratings.
A typical modern aldol addition reaction, shown above, might involve the nucleophilic addition of a ketone enolate to an aldehyde. Once formed, the aldol product can sometimes lose a molecule of water to form an Î±,Î²-unsaturated carbonyl compound. This is called aldol condensation.A variety of nucleophiles may be employed in the aldol reaction, including the enols, enolates, and enol ethers of ketones, aldehydes, and many other carbonyl compounds. The electrophilic partner is usually an aldehyde or ketone (many variations, such as the Mannich reaction, exist). typical modern aldol addition reaction, shown above, might involve the nucleophilic addition of a ketone enolate to an aldehyde. Once formed, the aldol product can sometimes lose a molecule of water to form an Î±,Î²-unsaturated carbonyl compound. This is called aldol condensation.