Aldol condensation | Alpha Carbon Chemistry | Organic chemistry | Khan Academy

Base-catalyzed mechanism for aldol addition and aldol condensation. Created by Jay.

Organic Chemistry on Khan Academy: Carbon can form covalent bonds with itself and other elements to create a mind-boggling array of structures. In organic chemistry, we will learn about the reactions chemists use to synthesize crazy carbon based structures, as well as the analytical methods to characterize them. We will also think about how those reactions are occurring on a molecular level with reaction mechanisms. Simply put, organic chemistry is like building with molecular Legos. Let's make some beautiful organic molecules!

About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content.

For free. For everyone. Forever. #YouCanLearnAnything

[j.a.]

Hey everyone, just to clarify, -OH is a good leaving group in this situation. It does not get converted to H2O.

[visheshjain]

-OH is not a good leaving group, thats why we make it -OH2+ and then make it leave, but at 6:10, you made -OH leave, how?

[DonotWorryIAmHere]

Only constructive criticism:

He should've shown the protonation of the -OH group before it left! ( -OH "hydroxide" is a TERRIBLE LEAVING GROUP) other than that, thanks for the brilliant clarification! -cheers!

[grant]

Where does the initial OH- come from if it is introduced in solution as NaOH, then how does it break apart and retain its charge?

[kamh]

The reason why the OH group can leave is because the reaction proceeds via an E1CB where CB means conjugate base. The protons on the alpha carbons ie the ones that are adjacent to the carbonyl are relatively acidic and so can be deprotonated by a weak base. This results in the enolate anion to form which is a relatively stable conjugate base. although this anion is stable it still prefers to lose an OH group ( Due thermodynamic stability reasons) and so the oxygen on the enolate ion collapses back which kicks of the adjacent double bond which then subsequently kicks off the OH group.
Hope this helps.

[katp]

Hey,

So does the -OH group get protonated before it leaves or no? Some people (in the comments) are saying yes and some are saying no. If it doesn't, can you explain why not?

[zahrashahabinezhad]

Why can't OH be removed from the aldol before the deprotonation?

[bonbonpony]

What does the heat change in this picture so that the reaction can proceed further than without it?

[kristinaf.]

Could somebody verify, (English is my third language) the aldol consendation is always as a two step mechanism to view at? First step, aldol addition then the actual consendation?

[martinofgliwice]

May I synthesise 2, 6-dimethylhex-2-enone from 5-oxo-4-methylheptanal via intramolecular aldol condensation?

[asheearif]

Uhhh gooosshhhh what the hellll... m still in this confusion what is the difference b/w aldol reaction and aldol condensation

[thelabadabada]

Why is it called a condensation reaction ? whe is the elimination of water ?

[dr.abeyweera]

Can you explain the conversion of 1 octen 3 one to 1 octen 3 ol