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Q4. Two unknowns (A and B) have the same molecular formula ($C_4H_8O$). Both unknowns are insoluble in
water, 5% NaOH, and 5% HCl, but they are soluble in concentrated sulfuric acid. The unknown (A)
gives a negative chromic acid test, but (B) gives a positive chromic acid test. However, both
unknowns (A and B) give orange precipitates upon the addition of 2,4-dinitrophenylhydrazine (2,4-
DNPH). (4 points)
A- Write the chemical structure for both unknowns. (2 points)
B- Write the chemical equation for the formation of 2, 4-dinitrophenylhydrazone derivative of A or B.
(1 point)
C- Write the chemical reaction of B with Chromic test: (1 points)
Q5- Draw a possible structure for a molecule $C_5H_{10}O$ that gives a positive Lucas test after
heating and does not react with $Br_2/CH_2Cl_2$? Write the chemical reaction with Lucas test.
(3 points)
A- Chemical Structure: (1 point)
B- Write the chemical reaction with Lucas test: (2 points)
Q6- Draw the structure of a compound $C_5H_8O$ that reacts with 2, 4-dinitrophenylhydrazine,
decolorizes bromine in dichloromethane but does not give a positive iodoform test. (3 points)
A- Chemical Structure: (1 point)
B- Chemical reaction with $Br_2/CH_2Cl_2$: (2 points)
Final Exam - 311-Fall-2023-2024-2024
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