Exploring Alkyl Groups and their Role in Organic Chemistry

In summary, alkyl groups are functional groups in organic chemistry made up of one or more single-bonded carbons with one degree of unsaturation from hydrogen. They are attached to the carbon backbone of a molecule and can also be attached by double or triple bonds, which would make them alkenyl or alkynyl groups. They are considered the most simple functional group and can consist of carbon chains along with their carbonyl group. They are not limited to just carbon and hydrogen atoms, but can also contain other elements.
  • #1
MycelliumMan
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I'm a bit confused about what alkyl groups are in organic chemistry. I thought functional groups by definition where groups of atoms which contained at least 1 element other than carbon or hydrogen which were connected to the carbon skeleton of the molecule.

What are alkyl groups then? I read about them on wikipedia and they mentioned things about free radicals. What the hell have free radicals got to do with this?

I'll use methionine as an example
http://upload.wikimedia.org/wikipedia/commons/2/23/Methionin_-_Methionine.svg
at the left side of that molecule there is a methyl group attached to the Sulfur atom. I only know this because I read an example they give in a book. First of all what makes this a methyl "group"? Is it a group because its not actually part of the carbon chain but instead its just a carbon atom separated from the main chain by that sulfur atom? Where do free radicals come into this? Theres no lone electron attached to that carbon atom seeing as its saturated by those hydrogen atoms.

Am I getting something mixed up here or have I got the right idea as to what alkyl groups are? Are they just groups of carbon atoms that are separated from the main chain?

Another thing does "R" always refer to an alkyl group or can it refer to any elements? For example what makes a ketone group and different from a plain old carbonyl group or an aldehyde? Can ketones only consist of carbon chains along with they're carbonyl group or can you have ketones which consist of any elements?
 
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  • #2
Functional group don't have to contain atoms other than carbon or hydrogen. An alkyl is the 'most simple' functional group, one or more single-bonded carbons with one degree of unsaturation from hydrogen (such as a methyl group). I guess it's not really directly stated that alkyl groups are made up of the same stuff as the carbon backbone they're attached to, but, that's how it goes.

When you have a compound like, say, 2-ethylpropane, the 'ethyl' in that would be an alkyl group attached to the second carbon of the propane chain. So that's pretty much the whole of it; alkyl groups are just carbon and hydrogen functional groups with only single bonds that are attached to the carbon backbone in organic compounds. Mind you, if they're attached by a double or triple bond they become alkenyl or alkynyl groups.
 
  • #3


Alkyl groups are groups of carbon and hydrogen atoms that are attached to a larger molecule. They are considered to be the simplest form of organic compounds and are commonly found in many organic molecules. Alkyl groups are important in organic chemistry because they can influence the physical and chemical properties of a molecule.

In the case of methionine, the methyl group is considered an alkyl group because it is a carbon atom attached to the sulfur atom, which is then attached to the larger molecule. This group is important in the function of methionine as it can participate in various chemical reactions.

The mention of free radicals in relation to alkyl groups may be referring to the fact that alkyl groups can be easily removed from a molecule, leaving behind a free radical. This can occur through various reactions, such as homolytic cleavage of a bond.

The letter "R" in organic chemistry is often used as a placeholder for any alkyl group. It can also refer to other functional groups, depending on the context. For example, in a ketone molecule, "R" would represent the alkyl group attached to the carbonyl carbon. In general, "R" can refer to any substituent attached to a larger molecule.

In terms of the difference between a ketone and a carbonyl group, a ketone is a specific type of carbonyl group where the carbonyl carbon is attached to two alkyl groups. A carbonyl group, on the other hand, can refer to any molecule that contains a carbon-oxygen double bond. So, while a ketone is a type of carbonyl group, not all carbonyl groups are ketones.

In summary, alkyl groups are important components of organic molecules and can influence their properties. They are groups of carbon and hydrogen atoms attached to a larger molecule and can be easily removed, leaving behind a free radical. The letter "R" is often used as a placeholder for alkyl groups in organic chemistry. Ketones are a specific type of carbonyl group, where the carbonyl carbon is attached to two alkyl groups.
 

1. What are alkyl groups and how are they formed?

Alkyl groups are hydrocarbon chains that are composed of carbon and hydrogen atoms. They can be formed through the substitution reaction of an alkane with a halogen, or through the addition of a carbon chain to a molecule.

2. What is the role of alkyl groups in organic chemistry?

Alkyl groups play a crucial role in organic chemistry as they can influence the physical and chemical properties of a molecule. They can also act as functional groups, which determine the reactivity and behavior of a compound.

3. How do alkyl groups affect the boiling point of a molecule?

Generally, molecules with larger alkyl groups have higher boiling points due to stronger intermolecular forces between the molecules. This is because larger alkyl groups have more surface area for van der Waals forces to act on.

4. Can alkyl groups participate in chemical reactions?

Yes, alkyl groups can participate in various chemical reactions such as substitution, elimination, and addition reactions. Their reactivity depends on the functional groups attached to them and their position in the molecule.

5. How can alkyl groups be identified in a molecule?

Alkyl groups can be identified by their characteristic carbon-hydrogen bonds, which produce a peak in the infrared spectrum. They can also be identified by their unique chemical shifts in proton and carbon-13 NMR spectra.

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