Comments on: Oxidation Ladders

By: suparna bhattacharjee

suparna bhattacharjee — Tue, 11 Jul 2023 06:26:47 +0000

I have this query. Before the beginning of second ladder, the note says “similarly, if you start with an alkane with secondary carbon…….”
My question is:
An alkane with a secondary carbon also has primary carbons. How a primary or a secondary carbon be oxidized selectively as per our requirement, using the same oxidizing agents(PCC, H2CrO4)

By: James Ashenhurst

James Ashenhurst — Wed, 28 Jun 2023 17:42:02 +0000

In reply to Tom Daniel.

Good eye.

I would say that in order to call something an oxidation, you’d have to look at the *net* change across two carbons if it’s occuring across a double bond.

For conversion of the primary alcohol to the alkene, the end carbon goes from -1 to -2 (reduction). The internal carbon goes from -2 to -1 (oxidation). So on net this is neither oxidation nor reduction.

For hydration of the alkene (alkene to secondary alcohol) the end carbon goes from -2 to -3 (reduction). The internal carbon goes from -1 to 0 (oxidation). So on net this is again neither oxidation nor reduction.

By: Tom Daniel

Tom Daniel — Tue, 27 Jun 2023 15:53:48 +0000

Is it just me or does it seem like there is oxidation in the final examples? Take the bottom example 1 alcohol -> alkene-> 2 alcohol. The oxidation number of the carbon attached to OH in the 1 alcohol is -1 oxidation state, then in the 2 alcohol it seems to be 0? Is that not an oxidation?

By: James Ashenhurst

James Ashenhurst — Tue, 29 Jun 2021 20:22:04 +0000

In reply to Sneha Basu. Halogenation of alkanes, followed by elimination with strong base.

By: Sneha Basu

Sneha Basu — Tue, 29 Jun 2021 17:40:33 +0000

What are the reagents that help conversion of alkane to alkene and alkyne?

By: James Ashenhurst

James Ashenhurst — Wed, 18 Sep 2019 16:13:32 +0000

In reply to Neil.

Yes, it’s not “self-consistent” because the number of carbons in each molecule differs – exactly as you said.

By: Neil

Neil — Sat, 10 Dec 2016 02:58:02 +0000

In reply to James. Sorry, this is still a little unclear to me. What is meant by "self-consistent"? Does it mean that to illustrate the idea clearly you have to assume that these "extra carbons" came from another reagent that isn't shown?

By: Jeremy

Jeremy — Tue, 15 Nov 2016 14:08:33 +0000

In reply to Roman.

Also noted a single bond is identified as a sigma bond and a double bond is termed a pi bond.

Source
http://Www.masterorganicchemistry.com

By: Rich Aversa

Rich Aversa — Tue, 28 Jun 2016 14:46:36 +0000

I’m a little sketched out by the aldehyde alkyne ketone horizontal “rung”. Looking at the carbonyl carbon, its oxidation state is +1 in the aldehyde and +2 in the ketone. The alkyne’s two functional carbons are 0 and -1. Even adding the oxidation states of the alpha carbons to the ketone and aldehyde, it doesn’t seem like these three compounds are all the same oxidation state. I agree they are in a sense on the same oxidation “level”, but the numbers don’t seem to add up. The bond breaking/forming argument is a strong one, but it may be complicated by the fact that the aldehyde is missing a carbon relative to the two other compounds.

By: Patrick Keller

Patrick Keller — Sun, 12 Jun 2016 21:56:56 +0000

In reply to Xuan. The weak oxidizing agent that will only react with aldehydes and convert them to Carboxylic acids is the Tollens Reagent, which is Ag2O and NH4OH. It ignores alcohols