Why don't carboxylic acids undego aldol reactions?

Question

If you have a dicarboxylic acid (HO2C((CH2)4)CO2H)
this is a dicarboxlic acid molecule with 4 intevening carbons, if you treat this with NaOH, H20 shouldnt a alpha hydrogen molecule be removed and attack of the opposite carbonyl occur similar to a aldol reaction of a dialdehyde?
This should form a cyclic molecule with two carboxylic acids. It is obvious that esters undergo aldol reactions (claisen condensation) and aldehydes do also, so wouldnt something in between, a carboxylic acid do the same thing?
Please explain and note any sources, this was a past exam problem that I think I got wrong, so I would appreciate answers quickly before the results are out because I am quite anxious to know how I did since almost all of my friends have converted both carboxylic acids to esters and did claisen condensation.

Answer 1

Lancenigo di Villorba (TV), Italy

ABOUT THE ACID
The Organic Acid interesting your doubts is BUTANDIOIC or SUCCINIC ACID, (CH2COOH)2.
As you wrote, it belongs to CARBOXYLIC ACIDs instead the CARBONYLIC COMPOUNDs or the ESTERs.

ABOUT ALDOLs
As you wrote, the latter two class of Chemical Compounds may take part to ALDOLIC REACTIONs.
I am comparing these latters in order to ALDOLIC CONDENSATION, e.g. I choose mix them versus Benzaldehyde

i) ALDEHYDEs : Acetaldehyde is employed to convert Benzaldehyde toward Cynnamic Aldehyde

CH3CHO(aq) + C6H5CHO(aq) <---> by means of OH- ions
<---> C6H5CH=CHCHO(aq) + H2O(aq)

ii) KETONEs : Acetone is employed to convert Benzaldehyde toward BenzalAcetone

(CH3)2CO(aq) + C6H5CHO(aq) <---> by means of OH- ions
<---> C6H5CH=CHCOCH3(aq) + H2O(aq)

iii) ESTERs : Ethyl-Acetate is employed in addiction on Benzaldehyde toward Ethyl-Cynnamate

CH3COOCH2CH3(aq) + C6H5CHO(aq) <---> by means of OH- ions <---> C6H5CH=CHCOOCH2CH3(aq) + H2O(aq)

FUNDAMENTs
The "Key-Compound" involved in these Reactions is a VERY REACTIVE AND UNSTABLE SPECIES, e.g. "Carbanion Intermediate".
The Carbanion may form by means of the
ALPHA-HYDROGEN LOSING since they behave as Acidic Hydrogen Atoms.
Thus, the ALDOLIC REACTIONS run owing to
Alpha-Hydrogen Atoms in Alkaline Aqueous Media

R'R''CH-C(=O)-R''' + OH- <---> R'R''C=C(R''')-O- + H2O

CARBOXYLIC ACIDs are Protic Compounds, that are Compounds having Hydrogen Atoms VERY VERY MORE ACIDIC THAN Alpha-Hydrogen Ones

R'R''CH-COOH + OH- <---> R'R''CH-COO- + H2O

IN THIS FASHION, Carboxylic Acids CANNOT FOLLOW THE ALDOLIC WAY.


I hope this helps you.

Answer 2

The reaction of phenols with carboxylic acids isn't very efficient, and in no way interior the presence of base. they don't seem to be nucleophilic sufficient. the superb way of coming up an ester of a phenol is to apply an acid chloride (acyl chloride) or anhydride as a exchange of the acid.

Answer 3

Simply because the carboxylate anion is more stable than the carbanions.