Why is NaOH added in aldol condensation?
NaOH it undergoes self condensation as it contains alpha-hydrogen atom in its compound forming β-hydroxyaldehyde (an aldol) namely 3-Hydroxy butanal. This compound upon further heating will eliminate a molecule of water forming aldol condensation product namely Crotonaldehyde Or But-2-en-al.
Is NaOH a reagent or catalyst in aldol condensation?
Dilute strong alkalis such as NaOH or KOH or Ba(OH)2 are used as aldol reagents.
Why is HCl used in aldol condensation?
All Answers (7) A low yield is obtained with the use of HCl in aldol condensation in acid catalysis for the synthesis of hydroxychalcone . Adol condensation is performed in alkaline medium as it is carbanion addition reaction to carbonyl group . For acid catalysed reaction the enol form must be generated.
Why is conc NaOH used in Cannizzaro reaction?
A 50\% concentrated NaOH solution is generally used in Cannizaro reaction as it is used for aldehydes which do not have α-H. (There are a few exceptions though) In normal aldol condensation, alpha hydrogens are more acidic so a weaker base can abstract it.
What is the function of NaOH in the preparation of Dibenzylideneacetone?
According to claisen aldehydes in the presence of sodium hydroxide can condense with another aldehyde or ketone eliminating a water molecule. Thus, moles of benzaldehyde condense with one mole of acetone to give Dibenzal acetone.
What is crossed aldol condensation?
Crossed aldol condensation is a variation of aldol condensation in which two dissimilar carbonyl compounds (each containing alpha hydrogens) undergo the condensation reaction together. In such reactions, up to four different products may be formed.
Is NaOH a reagent or catalyst in this reaction?
Sodium hydroxide is a compound that is used as a reactant as well as a catalyst depending on the type of reaction. It is used as a reactant in different forms of reactions to yield hydrogen gas.
What does the reagent NaOH do?
Sodium hydroxide is widely used in biochemistry. It is a basic solution and has the ability to raise pH of chemical solutions, for example it useful for neutralization of acids.
Which molecule is possibly shows aldol condensation?
Ethyl 2-methylacetoacetate and campholenic aldehyde react in an Aldol condensation. The synthetic procedure is typical for this type of reaction. In the process, in addition to water, an equivalent of ethanol and carbon dioxide are lost in decarboxylation.
Which of the following compounds will undergo Cannizzaro’s reaction with conc NaOH solution?
Aldehydes with no α−H atom undergo Cannizzaro reaction on heating with cone, alkali solution. Hence, only C6H5CHO will undergo the reaction.
Why concentrated base is used in Cannizzaro reaction?
It is important to remember that the the Cannizzaro reaction is restricted to non-enolizable aldehydes. The strong base used for this reaction would initiate aldol and other reactions that take place via enolate anions. In this reaction the alcohol and acid products combine to form an ester.
Why is NaOH soluble in water?
When sodium hydroxide (NaOH) dissolves in water, it separates into positively – charged sodium ions (cations) and negatively – charged hydroxide ions (anions). It is very soluble in water and, like all gases, it’s solubility depends on the partial pressure of the gas.
What is the mechanism of aldol condensation?
Aldol Condensation Mechanism & Alpha Hydrogen Reactions. Aldol Condensation, in organic chemistry, is a condensation reaction of enol aka enolate and carbonyl compound. When enol ions react with carbonyl compound it forms a β-hydroxyketone or β-hydroxyaldehyde. This process is followed by dehydration which results in conjugated enone.
What is the difference between aldol reaction and Cannizzaro reaction?
The aldol reaction involves removal of a reasonably acidic alpha proton and formation of a C-C bond. The Cannizzaro reaction involves breakage of the much stronger C-H aldehyde bond. The reactions are probably always in competition but the formation of the new C-C favors the aldol when the enol ion is formed.
What is a crossed aldol reaction?
The condensation reaction between two different molecules of an aldehyde or ketone in a protic solvent such as water or alcohol constitutes the crossed aldol reaction. When condensation is between two different carbonyl compounds, it is called crossed aldol condensation.
What is the best book for aldol condensation?
For studying aldol condensation one can follow the NCERT chemistry textbook part-2 for class 12. The chapter named ‘Aldehydes, Ketones and Carboxylic acids’ in this book contains this process. What is crossed aldol condensation?