Steam Distillation

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Steam Distillation Oil of Cloves ORG I
LABORATORY PRE LAB LECURE
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• Distillations
• Steam Distillation
• Steam distillation arises from an interesting
  curiosity of immiscible systems
• The distillation of liquids that are fully
  miscible is governed by Raoults Law
• PT NAPA NBPB NCPC
  (1)
• The mixture will have its own unique boiling
  point
• The contribution of each component to the vapor
  phase is related to its partial vapor pressure
  and mole fraction
• 3. In the distillation of immiscible liquids, the
  two act as two separate liquids

A
B
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• Distillations
• Steam Distillation
• The total vapor pressure above an immiscible
  system is equal to the sum of the vapor pressures
  independent of their relative amounts
• PT PA PB PC
  (2)
• 5. The
  mixture will boil at a temperature
• 
  typically lower than either liquid
• 6. Consider a mixture of iodobenzene and water
• At 98 oC the value of each vapor pressure is

46 torr
714 torr

760 torr
Mixture boils!
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• Distillations
• Steam Distillation
• 7. The mole fraction of each component
  (nA and nB) in the vapor phase is given
  by the ratio of its partial pressure over the
  total pressure nA PA/PT (3) and
  nB PB/PT (4)
• 8. If the vapor is condensed, the resulting
  distillate has the same composition. The ratio
  of the mole fractions for A and B in the
  distillate is then given by Equation 5, which
  results from dividing equation 3 by equation 4
• nA/nB PA/PB (5)
• Thus in the case of the steam distillation of
  iodobenzene and water, the vapor phase,
  iodobenzene would only have a mole fraction of
  0.064 (46 torr/714 torr)
• But because it has a larger molecular weight (204
  vs. 18 grams per mole) about 0.7 grams of
  iodobenzene are collected for every gram of
  water
• In the gas phase the two are fully miscible, but
  once the vapor condenses the two are no longer
  miscible and can be physically separated

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• Distillations
• Steam Distillation
• B. Uses/Apparatus
• This method is typically used to extract the
  volatile components of plants for use in
  perfumery, flavors or aromatherapy products.
• Steam distillation is used in the industries that
  produce these products as well as amateur set-ups
  like this one

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• Isolation of Natural Products
• This isolation of a natural product from its
  native matrix is one of the oldest examples of
  applied organic chemistry medicines and herbal
  remedies prepared by early human civilizations
  are good examples of this
• This field undergoing explosive growth as we
  attempt to find interesting molecules in nature
  that can be used for medicinal purposes as well
  as for flavorings, dyes and cosmetics from a
  natural rather than synthetic source
• The American Chemical Society (ACS) publishes
• a Journal that covers recent developments in this
  
• highly interesting and important field
• Papers start with the isolation of the
• animal or plant from its native environment
• followed by the various separation and
  identification
• techniques used to identify each component
• Recently, the initial assays of the
  anti-microbial,
• anti-carcinogenic and toxicity behavior of each
• component are also reported

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When these isolations are for medicinal purposes,
the field is known as Pharmacognosy "Pharmacognos
y" derives from two Greek words, "pharmakon" or
drug, and "gnosis" or knowledge. Like many
contemporary fields of science, pharma-cognosy
has undergone significant change in recent years
and today represents a highly interdisciplinary
science which is one of five major areas of
pharmaceutical education. Its scope includes
the study of the physical, chemical, biochemical
and biological properties of drugs, drug
substances, or potential drugs or drug substances
of natural origin as well as the search for new
drugs from natural sources. Research problems
in pharmacognosy include studies in the areas of
phytochemistry, microbial chemistry,
biosynthesis, biotransformation, chemotaxonomy,
and other biological and chemical sciences.
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In today's experiment we will isolate oil of
cloves from cloves (Eugenia caryophyllata).
Cloves have been used as a flavoring agent for
food for thousands of years. In addition, oil of
cloves was one of the first know dental pain
killers...a few drops of oil of cloves will numb
the pain of a tooth ache. One formulation sold
on the market for tooth pain relief still
contains oil of cloves. Oil of cloves is rich in
eugenol (4-allyl-2-methoxyphenol) and contains a
trace amount of caryophphyllene.
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Steam Distillation of an Essential Oil
We will be using a modification of the
distillation apparatus in the text
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Steam Distillation of an Essential Oil
The liquid will be transferred to a large
separatory funnel and extracted with methlyene
chloride CH2Cl2
The essential oil extract is soluble in methlyene
chloride, not water So draining the lower
methylene chloride layer, and evaporating the
methylene chloride, will afford the extracted oil

H2O
CH2Cl2

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Steam Distillation of an Essential Oil
The methylene chloride extract will be dried by
passing it through a disposable pipette filled
with anhydrous Na2SO4 drying agent
you will obtain a weight of the material (it
wont be much) and calculate a recovery based
on the original mass of plant material
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Steam Distillation of an Essential Oil
qualitatively to determine which components are
in the oil
We will analyze the essential oil by gas
chromatography
and quantitatively to determine the relative
amounts of each component