5-isopropyl

Iso means 1 branch of methyl on 2^nd

Propyl is c2h4 not 6

Sec-butyl is c with 2 other c attache and another fcitonal group attached

Also iso thing

Propy is c3h8 not 6

Here propyl mean C3H5

2 minutes ago, HbWhi5F said:

 5-isopropyl

Iso means 1 branch of methyl on 2^nd

Propyl is c2h4 not 6

Sec-butyl is c with 2 other c attache and another fcitonal group attached

Also iso thing

Propy is c3h8 not 6

Here propyl mean C3H5

What do you want to know about all this? What is the question?

@exchemist need help understanding nomenclature

2 minutes ago, HbWhi5F said:

@exchemist need help understanding nomenclature

What, specifically, do you not understand, about the examples you posted?

Edited October 23Oct 23 by exchemist

@exchemist in 2nd example Propy is c3h8 not H6

in 3rd why not neo-something

Edited October 26Oct 26 by HbWhi5F

15 hours ago, HbWhi5F said:

@exchemist in 2nd example Propy is c3h8 not H6

in 3rd why not neo-something

"Neo"? where do you get that from? "Neo" forms no part of the standard nomenclature for these compounds. It is a prefix meaning "new", e.g. neoprene which was, when it was invented in the 1930s a "new" kind of synthetic rubber.

Also "propy" doesn't mean anything.

I'm afraid I cannot make sense of your question here. Can you try again and this time uses a few more sentences to explain more clearly what it is you want to understand?

48 minutes ago, exchemist said:

"Neo"? where do you get that from? "Neo" forms no part of the standard nomenclature for these compounds.

Actually, the 2,2-dimethylpropyl radical is also known as the neopentyl radical. Attached to some leaving group, it is notorious for its unreactivity towards nucleophilic substitution reactions. The steric hinderance of the three methyl groups on the beta carbon atom strongly inhibits S_N2 reactions, and because the leaving group is attached to a primary carbon atom, S_N1 reactions are also very slow (and if forced will lead to rearrangement to the more stable tertiary carbocation).

3 minutes ago, KJW said:

Actually, the 2,2-dimethylpropyl radical is also known as the neopentyl radical. Attached to some leaving group, it is notorious for its unreactivity towards nucleophilic substitution reactions. The steric hinderance of the three methyl groups on the beta carbon atom strongly inhibits S_N2 reactions, and because the leaving group is attached to a primary carbon atom, S_N1 reactions are also very slow (and if forced will lead to rearrangement to the more stable tertiary carbocation).

Ha, I stand corrected! This seems to be a term no longer recommended and for some reason it had entirely passed me by.

Proply is c3h8 not 6 but in 2nd and 3rd example in main thread, in 3rd it means - propyl mean C3H5

Iso means 1 branch of methyl on 2^nd but in 1st and 2nd example it doesn't follow that

@exchemist

18 minutes ago, HbWhi5F said:

Proply is c3h8 not 6 but in 2nd and 3rd example in main thread, in 3rd it means - propyl mean C3H5

Iso means 1 branch of methyl on 2^nd but in 1st and 2nd example it doesn't follow that

@exchemist

Propane is C3H8 (the 2N +2 rule). Propyl would be with one H missing, as it is a group joined to something else by one of the bonds to carbon, so C3H7- , unless the propyl group itself has further substituents. Yes, iso means it is branched with a methyl group on the 2nd carbon atom.

Your example (b) seems to follow that OK as there is an isopropyl group (C3H7) on the 5th carbon atom of the octane backbone.

Your example ( c ) likewise follows that rule OK, as there is an isopropyl group, this time written as CH(CH₃)₂, so again C3H7, on the 4th carbon atom of the decane backbone.

In your example (d) the confusing factor is that the pentyl, C5H11, side chain on the 5th atom is written as a propyl group but with itself having 2 further methyl substituents. Each of these takes the place of what would otherwise be a hydrogen atom, so the propyl chain is now C3H5 instead of H7, with 2 methyl groups bolted on in place of the missing H atoms.

8 minutes ago, exchemist said:

Propane is C3H8 (the 2N +2 rule). Propyl would be with one H missing, as it is a group joined to something else by one of the bonds to carbon, so C3H7- , unless the propyl group itself has further substituents. Yes, iso means it is branched with a methyl group on the 2nd carbon atom.

Your example (b) seems to follow that OK as there is an isopropyl group (C3H7) on the 5th carbon atom of the octane backbone.

Your example ( c ) likewise follows that rule OK, as there is an isopropyl group, this time written as CH(CH₃)₂, so again C3H7, on the 4th carbon atom of the decane backbone.

In your example (d) the confusing factor is that the pentyl, C5H11, side chain on the 5th atom is written as a propyl group but with itself having 2 further methyl substituents. Each of these takes the place of what would otherwise be a hydrogen atom, so the propyl chain is now C3H5 instead of H7, with 2 methyl groups bolted on in place of the missing H atoms.

Further note: There is a page on nomenclature here that may be helpful:https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Map%3A_Organic_Chemistry_(Smith)/04%3A_Alkanes/4.06%3A_Common_Names