This document provides a procedure for steam distillation. Steam is passed through a round-bottomed flask containing a sample mixture to be separated. A trap allows control of the steam flow and removal of water from the steam line. Condensate containing separated compounds collects in a receiver flask. Once complete, the distillate is extracted with t-butyl methyl ether in a separatory funnel. The ether layer is dried, filtered, and evaporated to obtain the purified compounds, which are weighed and stored. The procedure is described to recover citral from lemongrass oil through steam distillation and extraction.

1. Procedure for steam distillation
By: Dr. Robert D. Craig, Ph.D

2. Procedure for steam distillation
 In the assembly shown, steam is passed
into a 250 mL round bottomed flask
through a section of 6 mm glass tubing
fitted into a still head with a piece of 5 mm
rubber tubing

3. Procedure for steam distillation

4. Procedure for steam distillation
 This is then connected to a steam line

5. Procedure for steam distillation
 The trap serves two purposes:
(1) it allows water, which is in the steam line
to be removed before it reaches the round
bottomed flask and
(2) adjustment of the clamp on the hose at
the bottom of the trap allows precise
control of the steam flow.

6. Procedure for steam distillation
 A bent adapter attached to a long condenser
delivers the condensate into a 250 ml
Erlenmeyer flask.

7. Steam Distillation

8. Steam Distillation
 On page 113!
 Using a graduated cylinder, measure out
10 mL of Lemongrass oil (not lemon oil)
into a 250 mL boiling flask.
 Rinse the remaining conentents of the
graduated cylinder into the flask with a
small amount of t-butyl methyl ether

9. t-butyl methyl ether!
Will be used to recover citral
.

10. Steam Distillation
 Add 100 mL of water, make the
connections as in Figure 6.4, heat the
flask with a low flame, and pass in the
steam

11. Steam Distillation
 To start the steam distillation, heat the
flask containing the mixture on the
Thermowell to prevent water from
condensing in the flask to the point wher
water and product splash over into the
receiver.

12. thermometers, thermocouples,
and bulbs
 A thermowell allows the temperature
sensor to be removed and replaced
without compromising either the ambient
region

14. Steam Distillation
 Turn on the steam valve, being sure that
the screw clampl on the bottom of the trap
is open.
 Slowly close the clamp and allow steam to
pass into the flask.

15. Steam Distillation
 Try to adjust the rate of steam addition
and the rate of heating so that the waster
level in the flask remains constant.

16. Steam Distillation
 Unlike ordinary instillations, steam
distillations are usually run as fast as
possible, with proper care to avoid
splashing of material into the receiver and
the escape of uncondensed steam.
 Distill as rapidly as the cooling facilities
allow and continue until droplets of oil no
longer appear at the tip of the condenser.

17. Extraction
 Pour 50 mL of t-butyl methyl ether into a
125 mL separatory funnel, cool the
distillate and pour a part of it into the
funnel

18. separatory funnel

19. Extraction
 Shake the funnel, and let the layers
separate, discard the lower layer, add
another portion of distillate and repeat

20. Extraction
 When the last portion of distillate has been
added, rinse the flask with a small amount
of t-butyl methyl ether to recover adhering
citral

21. Extraction
 Use the techniques described in chapter 7
for drying, filtering, and evaporating the t-
butyl ether.

22. Extraction
 Take the tare of a 1-g tincture bottle,
transfer the citral to it with a pasture pipette,
and determine the weight and yield from the
lemongrass oil.

23. Extraction
 Label the bottle and store (in the dark) for
later testing for the presence of double
bonds (alkenes) and aldehyde groups

24. Extraction
 Looks like that’s it!

25. Recovery of a Dissolved
Substance!
 Should continue this???

26. Hit the lab!!!
.