The Vespiary

The Hive => Serious Chemistry => Topic started by: cueva on June 07, 2000, 06:21:00 AM

Title: mechanism of isomerization
Post by: cueva on June 07, 2000, 06:21:00 AM
how do isomerization reactions work? what's the mechanism? it bothers me to look at these reactionsa and accept dogmatically that they work without knowing HOW they work. the beauty of organic chemistry is the explanation of how reactions work, not the reactions themselves, right?

Title: Re: mechanism of isomerization
Post by: Blaze2 on June 07, 2000, 11:57:00 AM
Is not the isomerisation of an allylbenzene to propenyl known as a prototropic rearrangment

Title: Re: mechanism of isomerization
Post by: Rhodium on June 07, 2000, 01:17:00 PM
What is a prototropic rearrangement? "proton rearrangement"?

http://rhodium.lycaeum.org (http://rhodium.lycaeum.org)

Title: Re: mechanism of isomerization
Post by: CHEM_GUY on June 07, 2000, 11:57:00 PM
Isomerization has several different mechanisms by which they work and therefore is to exhaustive of a subject to try to tackel without some direction to focus upon.  Some are basic thermodynamics, the formation of more stable compounds, other are a consequence of intermeidatary compound formation, and other yet can be surface catalyzed, and the list goes on...

What specific isomerization are you inquiring about? 

This post is for informational purposes only an is not intended to facilitate illegal activity.
Title: Re: mechanism of isomerization
Post by: cueva on June 08, 2000, 07:24:00 PM
proton rearangement? sounds easy.  the question is still unanswered, how does it work (what is the mechanism)? specifically, the reaction im talking about is just a change in the position of a double bond (aka proton rearangement), say, safrole to isosafrole with CaO and base. what does the CaO accomplish? the base?

Title: Re: mechanism of isomerization
Post by: Rhodium on June 08, 2000, 11:02:00 PM
The CaO absorbs the water present in the KOH, forming Ca(OH)2

http://rhodium.lycaeum.org (http://rhodium.lycaeum.org)

Title: Re: mechanism of isomerization
Post by: Osmium on June 09, 2000, 01:16:00 PM
The KOH probably removes the benzylic hydrogen, the double bond migrates and the H(+) reattaches itself onto the terminal carbon atom of that 3-carbon chain. Maybe some sort of chain reaction takes place too, meaning the hydrogen comes from the benzylic position of a second safrole molecule.