Problem 71 - A Complete Resource Book in Chemistry for JEE Main

Question

Alizarin dye obtained from the root of madder plant is an anthraquinone derivative. Its structure corresponds to (a) 2,3 -dihydroxy anthraquinone (b) 1,2 -dihydroxy anthraquinone (c) 1 -hydroxy anthaquinone (d) 1,4 -dihydroxy anthraquinone

Step-by-Step Solution

Answer

Alizarin dye corresponds to (b) 1,2 -dihydroxy anthraquinone.

Step 1: Identifying the Key Component

Alizarin dye is an anthraquinone derivative. Anthraquinone is a core structure in many dyes, so identifying its modifications will help in determining the correct structure.

Step 2: Examining the Hydroxy Substituents

The question lists options with different hydroxy (OH) positionings on the anthraquinone ring. We need to identify which positions are relevant for alizarin.

Step 3: Recalling the Structure of Alizarin

Alizarin is known to have two hydroxy groups attached to the anthraquinone structure. These hydroxy groups are specifically at positions 1 and 2 on the anthraquinone framework.

Step 4: Matching the Structure to the Options

Compare our information that alizarin is 1,2-dihydroxy anthraquinone with the given options. Option (b) 1,2 -dihydroxy anthraquinone corresponds to this structure.

Key Concepts

Anthraquinone Derivatives

Anthraquinone derivatives are chemical compounds that are based on the anthraquinone molecule, which forms the backbone for many dyes and pigments, including alizarin. These derivatives are crucial in various industrial applications, especially in the dye industry. Anthraquinone itself is composed of three benzene rings fused together in such a way that a central quinone structure is formed. This core structure is modified by the addition of various functional groups to create different derivatives.

• These modifications allow the creation of a broad spectrum of colors and shades, crucial for textile dyeing.
• Common modifications include hydroxy substitutions, amino groups, and halogen atoms.
• The molecular structure of anthraquinone provides stability to dyes and helps them attach strongly to fabrics.

Understanding the essence of these derivatives is vital for grasping their chemical behavior and practical uses.

Organic Chemistry

Organic chemistry is a branch of chemistry concerned with the structure, properties, and reactions of organic compounds which contain carbon in covalent bonding. The interesting world of organic chemistry explores how carbon atoms join together to form complex molecules, like anthraquinone derivatives. It deals with molecules organized around chains or rings of carbon atoms. These structures often include other elements such as hydrogen, nitrogen, oxygen, and sulfur.

• Organic chemistry principles are used extensively in pharmaceuticals, plastics, fuels, and dyes.
• It is central to predicting reactions and transformations of organic compounds, which aid in creating useful substances like dyes.
• Organic reactions help understand how different functional groups influence the behavior of anthraquinone derivatives, aiding in the manufacturing of specific dye properties.

For students and chemists, mastering organic chemistry is key to innovating and manipulating chemical compounds efficiently.

Hydroxy Substituents

Hydroxy substituents refer to the functional group -OH, known as a hydroxyl group, added to an organic compound. In the context of anthraquinone derivatives, hydroxy groups play a significant role in determining the chemical properties and applications of a compound like alizarin. When positioned on the anthraquinone ring, hydroxy groups can alter solubility, reactivity, and color characteristics.

• The presence and position of hydroxy groups are crucial in defining the specific identity of anthraquinone derivatives as dyes.
• For alizarin, the 1,2-dihydroxy substitution enhances the color fastness and shades of red produced, distinguishing it from other dyes.
• Hydroxy groups can also form intramolecular hydrogen bonds, further affecting a compound's chemical behavior and stability.

Recognizing how these substituents work gives insight into the tailored modification of dyes for industrial purposes and helps predict their reactions in various environments.