Urea and Biuret Test

This page focuses on urea, its preparation, hydrolysis, and the biuret test for peptide bonds.

Urea:

• Prepared from carbon dioxide and ammonia
• Undergoes hydrolysis in acidic or basic conditions

Definition: Biuret test - A chemical test used to detect the presence of peptide bonds in proteins.

Key reactions:

1. Urea synthesis: CO2 + 2NH3 → CO(NH2)2 + H2O
2. Acid hydrolysis of urea: CO(NH2)2 + H2O + 2HCl → 2NH4Cl + CO2
3. Base hydrolysis of urea: CO(NH2)2 + 2NaOH → Na2CO3 + 2NH3

Highlight: The biuret test uses Cu(OH)2 in alkaline conditions to detect peptide bonds, resulting in a violet-pink color for positive results.

The page also includes a table summarizing various chemical tests, including the Trommer's test, test for polyhydroxy alcohols, and the biuret test, detailing their purposes, observations, and products.

Alkanes, Alkenes, and Alkynes

Alkany, alkeny, and alkiny are three fundamental classes of hydrocarbons with distinct properties and reactivity. Alkanes are saturated hydrocarbons that do not decolorize bromine water and undergo combustion and radical substitution reactions. Alkenes contain a carbon-carbon double bond, decolorize bromine water, and undergo electrophilic addition reactions following Markovnikov's rule. Alkynes have a carbon-carbon triple bond and also decolorize bromine water, undergoing addition reactions similar to alkenes.

Highlight: The reactivity of these hydrocarbons increases from alkanes to alkenes to alkynes due to the increasing degree of unsaturation.

Example: An example of an alkene addition reaction is the reaction of ethene with bromine to form 1,2-dibromoethane: CH₂=CH₂ + Br₂ → CH₂Br-CH₂Br