CDP (BUTEX) 2024
Two full Chemistry of Dyes and Pigments papers (WPE 305) from BUTEX Level-3 Term-I finals, 2024. Questions span chromophores and auxochromes, azo and phthalocyanine dye synthesis, and reactive and disperse dye chemistry.
Q1
BANGLADESH UNIVERSITY OF TEXTILES
B. Sc. in Textile Engineering ㅤ
Level-3 Term-I, Final Exám-2024
Subject: Chemistry of Dyes & Pigments (Code: WPE 305)
Time: 3.0 Hrs. Full Marks: 72
(Use separate answer script for Part: A and Part: B)
(All parts of a question must be answered consecutively)
Part: A
(Answer any three questions)
1. (a) What are chromophore and auxochrome? Classify colorants according to chemical structure.
(b) What is bathochromic and hypsochromic shift? How does substitution on an aromatic ring affect the λmax of a dye?
(c) How do functional groups like -SOH, -COOH, -NH₂, and -OH affect dye solubility and affinity for fibers?
[4+4+4=12]
2. (a) If the energy of a photon is 350 × J, determine the wavelength of the photon.
(b) Describe the synthesis process of the following dyes-
(c) Mention the significance of the naming of dyes “Dispersol Fast Yellow A 300”.
(d) Interpret the different strategies for Azo dyes and the pigment synthesis process.
[2+5+2+3=12]
3. (a) Why are the carbonyl dyes and pigments capable of providing various colors?
Q2
BANGLADESH UNIVERSITY OF TEXTILES
B. Sc. in Textile Engineering ㅤ
Level-3 Term-I, Final Exám-2024
Subject: Chemistry of Dyes and Pigments (Code: DCE 301)
Time: 3.0 Hrs. Full Marks: 72
(Use separate answer script for Part: A and Part: B)
(All parts of a question must be answered consecutively)
Part: A
(Answer any three questions)
1. (a) There are four key expectations or criteria for any Head of Dyehouse, particularly in the context of reactive dyeing of cotton fibre. What are those expectations, and explain why they are important to meet in the final products? Discuss how the chemistry of reactive dyes influences the process to meet those expectations.
[12]
2. (a) Allude to the journey of discovery of reactive dyes.
(b) Put down the structural features of reactive dye molecules.
(c) Arrange reactive dyes in order of their reactivity.
(d) Throw light on the chromogen in reactive dyes.