Kinetic vs. Thermodynamic Product

[utahjazz]

I tried searching old threads and couldn't find if this is right-

Thermodynamic product forms at lower T and is the more stable product

Kinetic product forms at a higher T and is the fastest forming product

Thanks

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[amar21]

i dont get what you mean...

what is T representing? Temperature?

If so, relating temperature is just one of many (some more important) variables in determining the outcome of anything...

 

[onetryfitsbest]

Increase in temperature always shifts in the endothermic direction.

 

[nihargala]

I think that sounds right...

Thermodynamic product is definitely most stable product and is favored at low temperatures..

On the other hand, at high temperatures, since there is a lot of energy in the form of heat, the most stable product is not necessarily the most formed. There is more energy (in terms of heat.. temperature) for lesser stable products to form.

I think that sounds right

 

[utahjazz]

i dont get what you mean...

what is T representing? Temperature?

If so, relating temperature is just one of many (some more important) variables in determining the outcome of anything...

Okay. Sorry, I was recalling a specific Q on a PT where they asked if the thermodynamic product formed at the higher or lower Temperature.

 

[onetryfitsbest]

Essentially, when you are at a higher temperature, more molecules have the KE to overcome the endothermic energy-diagram "hump" and exist at the higher energy state. Thus raising temperature favors/increases the predominance of the kinetic (least stable) product.

 

[theman120]

hey guys, I was pretty sure that the thermodynamic product formed under high temperatures....cuz it had a higher Ea barrier, therefore overcome with the higher temperature...thermooooo dynamic....idk just my line of thinking, pretty sure it's right, and the kinetic product is the one that's formed first under low temps......makes sense to me.

 

[MooseKing]

i remeber from class that the thermodynamic product will take a longer time to form compared with the kinetic product because it has a higher activation energy and this will be a more stable product (i.e. thermo control is favored for higher temps and longer rxn times).

 

[amikhchi]

i don't think TPR prep ever went over anything along the lines of the "thermodynamic" vs "kinetic" product, would someone mind explaining it?

 

[sv3a]

The kinetic product is the product that requires less activation energy to start the reaction but is less stable, so in lower temperature reactions (a 'low temperature' is relative based on the reaction) the kinetic product will form. This is because there is less energy available in low temps, and the thermodynamically more stable product requires a higher activation energy than the kinetic product. If the temperature is raised enough, there will be enough energy that the activation energy required for the more stable product's reaction will be met more easily, so the thermodynamic product will be formed. Also, over time some of the kinetic product will eventually become the thermodynamic product even at lower temps.

The best example I can think of is 1,2 (kinetic) versus 1,4 (thermodynamic) addition reactions in a diene.