Science

amount of cyclohexanol determines the theoretical amount of product so it must be measured accurately.

Place the round-bottomed (rb) flask into a 30 mL beaker to hold it upright, set this onto the balance and

press zero (this will set the weight of the container to zero – this is called taring the flask), and measure

in about 2.0 g (± 0.05 g, but weigh it exactly, e.g., 1.964 g or 2.033 g) of cyclohexanol by dropping it in

with a pipet. Using a buret in the hood, add about 0.5 mL of 85% phosphoric acid to the rb flask. Note

that the rb flask becomes warm - addition of acid to alcohol is exothermic. Set up a fractional

distillation apparatus in the same way as in the distillation experiment (remember the boiling chips). Be

sure to use the distillation column (in some rare cases a slightly longer narrower glass tube that looks a

lot like the distillation column may have inadvertently gotten mixed in to some of the lockers. Be sure to

not use this tube - this tube, a chromatography column used in another course, does not connect tightly.)

Use the black plastic connector to connect the flask to the distilling head. This is more resistant to the

reactants than is the white connector. Insulate the column by loosely wrapping it with a piece of

aluminum foil. Be sure to use an ice-cooled receiver. Otherwise product will evaporate and the odor

will be disagreeable.

Heat the mixture sufficiently to distill product over into the collection vial (remember to make a small

depression in the sand bath so that the flask may be lowered into it for effective heating). Unlike in a

normal distillation this first distillation can and should be done fairly rapidly, not at the usual rate of one

drop per 20-30 seconds, but instead at a rate of about one drop per second or two. (If liquid is not

collecting in the vial within about 20 minutes, something is wrong – there may not be enough heat, the

column may be packed too tightly, you may have measured the quantities...