What is Dealkylation?

Dealkylation is a chemical process through which alkyl groups are removed from a given compound. It can be somewhat challenging to define alkyls precisely without appealing to complicated chemistry terms, but in general these are molecular structures made up of hydrogen and carbon, usually arranged in circular fashion. Sometimes alkyl removal happens naturally, usually as a consequence of temperature shifts and decomposition processes, but more often it’s manipulated in a lab by researchers or scientists. Alkyl removal is a common part of organic chemistry studies at the university level and these sorts of labs are thought to help students grasp the varying roles of hydrocarbon groups. There are a couple of reasons why the process is advantageous outside of academic settings, too, though, perhaps most importantly when it comes to refining oil and petroleum and creating effective pharmaceuticals.

Alkys are a very general class of molecular components that contain a number of different hydrogen-carbon combinations. At its most basic level, an alkyl group is a functional group on an organic molecule that is derived from an alkane that has lost a hydrogen atom, and they’re often broadly represented by the formula C_nH_2n+1. An alkane, by way of reference, is an organic molecule made up of straight or branched chains of carbon and hydrogen atoms where the carbon-carbon atoms are joined exclusively by single bonds.

There are always a number of reasons why chemical reactions happen, and alkyl groups falling away or out of compounds is no different. Temperature change, decomposition, and the addition of various outside chemicals, whether through intentional manipulation or natural consequences, are some of the most common methods of change. There are generally two main processes: the addition of oxides and oxygen-based compounds, and the comparable addition of nitrogen-heavy chemicals. Both oxygen and nitrogen can bind to the hydrocarbon structures of certain molecules in such a way as to reorder the contents or cause shifts in the existing bonds, but usually only when the conditions are right.

Most of these sorts of reactions in organic chemistry are seen as a result of oxidative (O-) dealkylation. This process uses an oxide, a compound containing an oxygen atom and at least one other element, to draw away the alkyl group of an organic molecule through some form of reduction-oxidation, or “redox,” reaction. Through a change in carbon's oxidative state, the alkyl group breaks off.

O-dealkylation has become an important part of research into mammalian metabolism. Specifically, this research involves the human metabolism of pharmaceuticals and other foreign and chemical substances and the role that alkyl loss plays in that process. It also plays a significant role in the clinical laboratory, where it can be used to change the ability of a particular solution to donate electrons to other nearby particulates.

Nitrogen-based alkyl shifts, often referred to in the literature as N-dealkylation reactions, are less common but generally just as effective. The addition of nitrogen can similarly cause a reorganization of hydrocarbon bonding, but it often takes much longer; the addition of nitrous compounds can and often does change the overall nature of the compound in more profound ways than oxygen, too.

Dealkylation is an important part of the process that turns crude oil into more usable products. Benzene and methylbenzene, for example, are both hydrocarbons found in crude oil, but benzene is more commercially valuable. When methylbenzene is mixed with hydrogen and a catalyst, and heated to a particular temperature and under a specific amount of pressure, the methyl group is removed, producing benzene.

The process is also very important in the production of pharmaceuticals for both human and animal consumption. Removing alkyl groups can activate certain compounds in drug creation and can also promote things like better absorption and efficacy. In a similar vein, the reaction is also frequently harnessed by manufacturers of fertilizers and pesticides.