1.
1. List 2 types of interactions that the dye molecules can bind to the fibers. (4 points) 2. If
dichloromethane is used in extractions, Which layer is collected? Why? (6 points) 3. In synthesis
of cyclohexene, (6 points) a) Which impurity does make the distillate unclear? b) How does it
happen? c) How to remove this impurity?
Solution
1. types of ineraction swith the dye is hydrophobic interactions and dipole-dipole interactions.
2. If dichloromethane is used in extraction, having density greater than water. The layer which is
collected now would be organic in nature as the dichlormethane sits below the water layer and is
more volatile distills off first.
3. In the synthesis of cyclohexene
a) presence of trace amounts of water makes the distillated unclear.
b) The water present in the organic layer of the dehdyration distills off with the product.
c) drying the organic layer before distillation using anhydrous MgSO4 would help remove this
impurity and gives clear distillate.