[bornaprine]

Why do we need AcetoneDiCarboxylic Acid for the synthesis of Tropinone? If the reaction goes as (like) Mannnich Reaction why can't we use acetone?

Thanks for your help.

[macman104]

Compare the pka's of the alpha-hydrogen of acetone and the dicarboxylic acetone.

[azmanam]

pKa modulation.  Think about what other reagents are or are not included in this synthesis and what reagents you might need to add if you used acetone.  Might any additional reagents pose potential problems elsewhere in the synthesis?

Although with proper reagent control, there's no reason acetone cannot be used.

[bornaprine]

Compare the pka's of the alpha-hydrogen of acetone and the dicarboxylic acetone.

What information can I get from the pka of a substance? And where can I find the pka's of the substances?

[Mitch]

Rough list of pka values can be found in house:
http://www.chemicalforums.com/index.php?page=pkavalues

[bornaprine]

Thank you all very much but what do these values tell me?

[rr338]

bornaprine,
i know this is two years too late but the answer may be of use to other forum members.
and this is a good question
To understand the problem one must review
1 keto-enol tautomerism
2. aldol/claisen condensation
3. malonic ester/ acetoacetic acid synthesis
4. Mannich reaction.
the pka value allows one to estimate the equilibrium concentration of the reactive species,
or about what percent of the reagent exists in the reactive(enol) form at the ph in question.
acetonedicarboxylate will be more reactive than acetone, or it will react under milder conditions than acetone.
[malonic ester vs claisen cond]
Mannich reactions can produce a mixture of products.
[the reaction of methylamine, formaldeyde and acetone can produce four or more products, which one predominates and in what percentage can be influenced by the relative concentrations of reactants and the ph(this effects percentage of a material in its reactive form)]
also it is possible for acetone to aldol into diacetone alcohol.
so one might use acetonedicarboxylate so that the reaction will go under the conditions,
or so that the reaction will proceed at a greater/acceptable rate,
or in order to minimize the side products of this reaction.
selection of the particular starting materials and control of the ph allows one to cause the desired reaction to predominate over the other possible reactions so that one gets the desired product as opposed to something else, or in a greater yield.
hope my rambling helps.
i dont actually know what u would get with acetone or in what yield