What is Dealkylation?

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  • Originally Written By: Renee Malove
  • Revised By: C. Mitchell
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  • Last Modified Date: 15 July 2017
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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.

Understanding Alkyls Generally

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 CnH2n+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.


Why and When It Happens

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.

Oxidative Reactions

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 Processes

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.

Role in Oil Refining and Pharmaceutical Production

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.


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Post 1
Organic chemistry has come a long way from its early roots. Like most branches of science, it started with early observations of the way things work. As with all good science, it advanced by either proving or disproving an idea, or in science talk, a 'theory'.

Dealkylation is an advancement that is now in practical use. It doesn't always happen that way.

Vitalism is an example of an idea that was more or less abandoned in science. Vitalism is the idea that something living has a non-physical element that isn't contained in non-living things.

Both of these were developed and tested through scientific method.

One, vitalism, was thought to be observed, tested, could not be backed by data and so was abandoned. The other, Dealkylation was observed tested, proven and refined to have practical applications in life.

This is how science works.

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