Consider the following procedure: Place a magnetic stirring bar into a 250 ml ro
ID: 712020 • Letter: C
Question
Consider the following procedure:
Place a magnetic stirring bar into a 250 ml round bottom flask. Place 50ml of 2-ethoxyethanol and 11.5 g of patassium hydroxide pellets into the flask. Swirl the solution in the flask to dissolve a portion of the pellets. Add 13.5 ml of 3-chloro-3-methylpentane to the flask. Clamp the flask to a ring stand. Since strong base is a reagant in this experiment, grease the male joint of the condenser. Instert the condenser for heating under reflux. (A) Heat the mixture in the thermowell (At a low voltage setting) for 2.5 hours. (B) (C) Remove the heater to let the flask cool. (E) Collect the product fraction boiling between 50 and 80 degrees celsius in a tared 25 ml round bottom flask. (F) Record the weight of product in the flask.
Q.
(A) Give a balanced equation for the reaction occuring here.
(B) 2-ethoxyethanol has a boiling point of 136 degrees celsius so why is the reflux heated at a low voltage setting?
(E) During the fractional distillation the entire fraction of the product came over at about 60 degree celsius. Why?
Explanation / Answer
1) (C2H5O)-CH2 -CH2 -OH + NaOH =========> (C2H5O)-CH2 -CH2 -ONa + H2O
2-ethoxy ethanol 2-ethoxy sodium ethaoxide
(C2H5O)-CH2 -CH2 -ONa + CH3 -CH2 -C(Cl)(CH3) -CH3 -CH2 ========>
3-chloro 3-methyl pentane
(C2H5O)-CH2 -CH2 -O - C(CH3) (C2H5)2 + NaCl
2-( methyl, diethyl methoxy ) 2-ethoxy ethane [ ether is formed]
2) 2-ethoxy ethanol is reacted with sodium hydroxide to form sodium salt . this reaction is carried at low temperature, because at high temperature the reaction is explosive.
3) the formed proudt is ether , it is less boiling point than alcohol .thats why product boiling point is 800C .