Confused about oxidation number

[calios]

guys anyone can help me ?
im bit confused when talkin about oxidation number in alkyl group
like
R-NO₂
or
R-CN
when this compound react with reducing agent like H₂
can somebody explain me? most example in book or internet doesn't use hydrocarbon reaction
thank you :)

 

[Borek]

Oxidation number of what?

 

[calios]

oxidation number of R (alkyl) so its relate calculation with other

 

[Borek]

Does it matter? It doesn't change during reduction of -NO₂ or -CN.

Please remember that oxidation numbers don't exist - there is no physical property that can be measured and used to determine the ON, they are just an artificial accounting device.

 

[LudusRex]

Sure, let me try to explain oxidation numbers in the context of alkyl groups and their reactions with reducing agents.

Oxidation number is a concept used in chemistry to keep track of the number of electrons that are gained or lost by an atom in a chemical reaction. It is represented by a positive or negative number and indicates the overall charge of the atom in a compound.

In the case of alkyl groups, which are hydrocarbon chains with one or more carbon atoms attached to a larger molecule, the oxidation number is typically assigned to the carbon atom. This is because carbon is the most electronegative element in the alkyl group and therefore has the highest tendency to gain or lose electrons.

Let's take the example of R-NO2, where R represents the alkyl group. In this compound, the carbon atom in the alkyl group has an oxidation number of -3, while the nitrogen atom in the NO2 group has an oxidation number of +5. This means that the carbon atom has gained three electrons and the nitrogen atom has lost five electrons, resulting in an overall charge of 0 for the compound.

Now, when this compound reacts with a reducing agent like H2, the reducing agent donates electrons to the compound, causing a decrease in the oxidation number of the carbon atom. This reduction process can be represented as follows:

R-NO2 + 2H2 → R-NH2 + 2H2O

In this reaction, the carbon atom in the alkyl group now has an oxidation number of -2, as it has gained two electrons from the reducing agent. The nitrogen atom, on the other hand, now has an oxidation number of +3, as it has lost two electrons.

Similarly, in the reaction of R-CN with H2, the carbon atom in the alkyl group will have an oxidation number of -1 after reduction, while the nitrogen atom will have an oxidation number of +2.

I hope this helps clarify your confusion about oxidation numbers in alkyl groups and their reactions with reducing agents. Remember, oxidation numbers are simply a way to keep track of electron transfer in a chemical reaction and can help us understand the overall charge and reactivity of a compound.