malonic ester with urea gives
When malonic ester reacts with urea, it forms a compound known as barbituric acid. The reaction involves the condensation of urea with two molecules of malonic ester. This reaction is commonly referred to as the "malonic ester synthesis of barbituric acid."
To understand the reaction mechanism and the steps involved, we will break it down:
Step 1: Deprotonation of Malonic Ester:
The first step involves the deprotonation of one of the alpha hydrogen atoms in malonic ester. A strong base, such as sodium ethoxide (NaOEt), is typically used to deprotonate the malonic ester, generating the malonate ion.
CH2(CO2CH3)2 + NaOEt → CH2(CO2^- Na+)(CO2CH3) + EtOH
Step 2: Nucleophilic Addition:
Next, urea acts as a nucleophile and attacks the carbonyl carbon of the malonate ion. The nucleophilic addition occurs at the carbon atom adjacent to the carboxylate group.
CH2(CO2^- Na+)(CO2CH3) + NH2CONH2 → CH2(CO2^- Na+)(CO2CH3)C(=O)NHCONH2
Step 3: Tautomerization:
In the presence of acidic conditions, such as hydrochloric acid (HCl), the intermediate compound undergoes tautomerization. This means that rearrangement occurs, resulting in a more stable tautomeric form called barbituric acid.
CH2(CO2^- Na+)(CO2CH3)C(=O)NHCONH2 + HCl → C(CO2^- Na+)(CO2CH3)=NC(=O)NH2 + H2O
Overall Reaction:
Combining the above steps, the reaction can be summarized as:
CH2(CO2CH3)2 + NaOEt + NH2CONH2 + HCl → C(CO2^- Na+)(CO2CH3)=NC(=O)NH2 + H2O + EtOH + NaCl
Barbituric acid is an important intermediate in the synthesis of barbiturates, which are a class of drugs used as sedatives, hypnotics, and anticonvulsants.
So, in summary, when malonic ester reacts with urea, it undergoes deprotonation, nucleophilic addition, and tautomerization to form barbituric acid.