crude trimyristin - Chemistry

EXPERIMENT 1
ISOLATION OF OIL OF NUTMEG (CRUDE TRIMYRISTIN)
FROM NUTMEG
THEORY
Organisms, seeds, etc. are very complex mixtures and it is difficult to obtain pure single
substances from them. In this experiment we shall isolate a mixture of oils from nutmeg. The
main component of this mixture is the lipid, trimyristin, but there are many other components
which will also be isolated along with the trimyristin. As a result, the product obtained from this
experiment will be a mixture of trimyristin and many other compounds. In a future experiment,
we will recrystallize the crude sample to obtain a fairly pure sample of trimyristin.
NOTES
Distillation is a technique used for purification of liquids and for removing volatile liquids
from solid products. It consists of heating a liquid to its boiling point, at atmospheric or reduced
pressure, to convert it to its vapour and then condensing the vapour back to the liquid by
cooling.
The boiling point is the temperature at which the vapour pressure (escaping tendency)
of the liquid equals the atmospheric or applied pressure. Thus if you decrease the applied
pressure by evacuating the system, you decrease the boiling point. Pressurizing the system
increases the boiling point. The "escaping tendency" is related among other things to the
intermolecular forces which keep the substance in the liquid phase. These forces are
determined largely by molecular structure and hence boiling point is crudely characteristic of a
particular structure.
SAFETY
Steam: Live steam is, of course, at 100°C or above. Normally when the steam
tap is first turned on, a quantity of water, which has condensed in the line, must
be drained into the trough. Never attempt to drain this water into a beaker or
flask because clouds of scalding steam will follow it. DO NOT turn on the steam
unless the hose of a steam bath is attached. Avoid excessive steam flow rates -
a little steam and a lot of steam have the same temperature. WARNING: the

steam tap is the lever beneath the reagent shelf, the steam outlet is the jet
pointing out the side of the reagent shelf. This jet is aimed toward you.
NEVER DISTIL TO DRYNESS. Many organic solvents react slowly with air to
form peroxides which may explode violently if overheated. (Ethers are
particularly notorious in this regard.) As long as a few drops of solvent remain
and the glass is “wet”, it is near the boiling point of the solvent. When it is dry,
however, some heat sources can quickly raise the temperature several hundred
degrees and any high boiling liquids present are similarly overheated. The use
of steam as a heat source largely avoids this problem.
ALWAYS USE A BOILING CHIP. Liquids tend to superheat, that is to reach a
temperature above the boiling point without boiling. ( A liquid will evaporate from
the surface at any temperature. It is boiling when it is being converted to the
vapour phase throughout its volume.) When a bubble of vapour forms in such a
superheated liquid, its growth rate may be almost explosive. The liquid "bumps"
and if it is flammable and an ignition source is near by, a fire can result. A
boiling chip or stone has micropores which, especially on heating, emit tiny air
bubbles which serve as nucleation centres and prevent superheating and,
hence, bumping.
Thermometer placement.
TECHNIQUE
In order to record the true boiling or vapour temperature, the thermometer
must be correctly placed. If it is too far down, it may be in vapours of higher
temperature than those being collected. If it is placed too high, it will be above
the vapours. Either way, the temperature recorded will be incorrect. Generally,
the thermometer is placed so that the middle of the mercury bulb is even with the
bottom of the side-arm.
Distillation rate.
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In theory, the boiling point is independent of heat input but in practice,
overheating of liquid and vapour occur if the heat input is excessive.
Consequently, a slow, steady distillation rate should be maintained. This rate
can vary from a few drops per minute to several millilitres per minute, depending
on the degree of separation desired. Slower distillation normally gives better
separation. If the thermometer bulb and the distillation head are not always

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bathed in condensed and returning material, the temperature may fluctuate. On
the other hand do not overheat the system.

PROCEDURE
Weigh out 10 g of ground nutmeg and place it in a 500 mL round bottom flask. Add 90
mL of hexane and a few boiling chips and set up an apparatus for reflux (See the figure on
page 125) . Reflux the hexane-nutmeg mixture, using a steam bath (see Safety: above) as the
source of heat, for 30 min. Determine the mass of your clean, dry 250 mL round bottom
flask, containing a few boiling stones. Remove the mixture from the steam bath (dry any
water from the flask and condenser before removing the condenser from the flask) and while it
is still warm, filter off the residue of the nutmeg by gravity filtration, collecting the filtrate in the
preweighed 250 mL round bottom flask. Rinse out the flask in which you did the original
extraction (i.e. the 500 mL flask) with about 5-10 mL of fresh hexane and filter the washings into
the 250 mL flask. Dispose of the filter paper in the dump in the fume hood.
Set up the apparatus for simple distillation (See the figure on page 124) and distil off the
hexane using a steam bath. Record the temperature (to the nearest 0.5 °C) when the first drop
of distillate is collected in the collection flask and record the highest temperature reached during
the distillation. This will be the collection range for the distillation. Continue heating for 5
minutes after the last of the hexane has distilled over. Dry any water from the distillation flask
and connecting adapter. Dispose of the distilled hexane in the appropriate dump in the fume
hood (make sure you know which flask contains the hexane). Remove the flask containing the
crude product and weigh the flask. Record the mass of crude product. At this point, the
sample likely contains a trace of hexane and will therefore show an artificially high mass. Leave
the flask containing the crude product in your locker for a week (uncorked).
After the product has dried for a week, determine the mass of the flask. Record the
mass. Did the mass change over the week? Store this round bottom flask in your locker until
it is purified in the next lab period.
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REPORT
In the “purpose section”, clearly explain the purpose of the main steps in this
experiment. In the “discussion section”, comment on the change in product mass from week
one to week two. Calculate the percentage recovery of product (be sure to base this on the
mass of product after it has dried for a week) and compare this to the expected value (see
note 2). List sources of error to account for any discrepancy.

QUESTIONS (FALL 2010)
1. After the reflux, the mixture is filtered to remove the solid residue. This filtration
should be done while the solution is still warm. Why?
2. Explain the difference between a saturated solution and a saturated hydrocarbon.
Your explanation should explain what the word “saturated” refers to in each case.
3. BRIEFLY - how would you determine how much fat is present in a sample of
hamburger?
QUESTIONS (WINTER 2011)
1. If there was no water flowing in the condenser during the reflux step, what effect
would this have on the results of the experiment?
2. If the nutmeg had been refluxed with water instead of hexane, would the experiment
have been successful? Explain.
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3. When percolating coffee from ground coffee beans, why should the water be near
the boiling point (instead of room temperature)?

NOTE 1
The following procedure can be used to clean the round bottom flasks used in this
experiment. The product is not soluble in water and not easily dissolved in cold organic
solvents. To remove the remaining traces of crude product, you will need to use soap and HOT
water (scrub with a brush). Then use water to rinse out all of the soap. To remove the water
from the flask, rinse it with two small portions (2–3 mL) of acetone by placing the tip of the
acetone squeeze bottle in the neck of the flask and allowing the acetone to run down the inside.
Rotating the flask while adding the acetone will help rinse any water droplets off the side of the
flask. The flask can be swirled then the acetone poured out into the sink. Let the flask air dry
for a few moments and If the flask is still not dry, repeat the above procedure. Drawing air
through the glassware, by means of the aspirator or by holding the piece of glassware over the
window vent, will speed the drying process. Note that each "wash" should use no more than 3
mL of acetone. Using excess acetone does not dry the equipment any better and is wasteful.
NOTE 2
When you isolate a product from a natural source, you should look up the expected
percentage and compare it to the experimental percentage. The expected percentage can be
found in a number of places. For example, you might try the MERCK index. This book is
available in the Chemistry Help Center (C-2012). This book contains information about
chemicals, natural products, plant extracts, etc.
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To find information about the expected yield of crude trimyristin from nutmeg, you should
look up the listing for "nutmeg" , not the listing for "trimyristin". If you look up "trimyristin", it will
give you information about the compound, trimyristin. However, since trimyristin can be isolated
from more than one source, this listing will have nothing about the trimyristin content in nutmeg.
If you look up the listing for "nutmeg" in the cross index, you will find that it is actually listed
under its Latin name. This listing will tell you that there are two kinds of oils found in nutmeg
(fixed oil and volatile oil) and the percentage of each is also given. You must then look up the
two kinds of "oil of nutmeg" to determine which one contains the trimyristin. Note that the
method used to extract the oils from nutmeg in this experiment, will likely extract both the fixed
and volatile oils. Thus the expected yield of product, which in this case is very impure
trimyristin, will be the total of the fixed and volatile oils.
The information can also be obtained by consulting a book dealing with spices or by
using the internet. Note that for any natural product, the expected percent recovery will not be
given as a single value, but as a range of values.

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N.B. Be sure to record a reference for where the data was found. This should include
the title of the book, the edition and the page number (or the address if the internet was used).