LABORATORY MANUAL
of
ORGANIC CHEMISTRY
by
DR. H. C. SCURLOCK
PROFESSOR OF CHEMISTRY, HOWARD UNIVERSITY
Printed for use in Howard University
WASHINGTON, D. C.
Beresford, Printer, 605 F Street, N. W.
1910
LABORATORY MANUAL
of
ORGANIC CHEMISTRY
by
DR. H. C. SCURLOCK
PROFESSOR OF CHEMISTRY, HOWARD UNIVERSITY
Printed for use in Howard University
WASHINGTON, D. C.
Beresford, Printer, 605 F Street, N. W.
1910
TO THE STUDENT.
This little manual constitutes an introduction to the study of Organic
Chemistry which shall aid the beginner to understand from the first the
principles of the subject as they are presented. About forty exercises
given here by no means represent the whole of the practical work in the
laboratory. They are selected with the view of attaining the end already
mentioned, and are the minimum requirement in any course in Organic
Chemistry in this University at the present time.
A written report upon each exercise is required, and students will be
quizzed orally in groups or individually upon the same subjects, as well
as meet them in the written examinations. To secure a passing grade
there must be satisfactory evidence of understanding the subject matter
to which these exercises have reference.
Copyright, 1910,
By H. C. Scurlock.
ORGANIC CHEMISTRY.
HYDROCARBONS.
The simplest organic compounds are the hydrocarbons—
bodies which contain carbon and hydrogen only. Some
chemists look upon all other organic compounds as deriva¬
tives of the hydrocarbons, and define organic chemistry as
the chemistry of the hydrocarbons and their derivatives.
While the large number of substances studied in inor¬
ganic chemistry have their origin in the various combina¬
tions of all the elements, the thousands of known organic
substances are composed chiefly of only four elements.
They all contain carbon and hydrogen, many of them con¬
tain oxygen and nitrogen, while sulphur and phosphorus
are also found sometimes. It is not to be understood,
however, that no other elements ever enter into organic
compounds.
Hydrocarbons are divided into two principal classes—
the open chain, or acyclic, and the closed chain, or cyclic.
By a chain is meant the linking of several atoms together
as a nucleus from which compounds may be built up.
Carbon is the chief element in organic substances, and is
the element which forms the chains giving rise to the
bodies studied in organic chemistry.
An open-chain hydrocarbon is one, the nature of which
is such that other carbon atoms may be made to enter it,
thus increasing the carbon content and forming a new
nucleus whose properties are different from those of the
4
original nucleus. For example, ethane is C2H6, having
two C atoms in the nucleus. It may be changed to pro¬
pane, C3H8, having three C atoms in the nucleus in the
following manner : Treated with bromine, ethane will yield
brom-ethane
H H
I i
H —C —C—Br,
I I
H H
which, treated with methyl bromide and metallic sodium,
will add on C.
H H
H H H
H — C — C—jBr + Br
| | ! +2Na
H H
CH3=H— C— C —C —H + 2NaBr.
H H H
In a closed-chain hydrocarbon no additional carbon atoms
can be made to enter into the original group. By Fittig's
synthesis, benzene, which is usually represented by a closed
hexagonal ring, can be changed into a compound having
seven carbon atoms, C7H8. But it can be proved that the
additional C atom does not enter the ring, but is attached
as a side chain.
Hydrocarbons are said to be saturated when only one
bond of affinity links the C atoms; they are unsaturated
when more than one bond of attachment exist between any
two C atoms.
H H H H H
III. II H
H—C—C—C—H H—C—C=C<S
III I H
H H H H
Saturated hydrocarbon] Unsaturated hydrocarbon.
PETROLEUM :
A mineral, a dark green, thick liquid found in the ground in many parts of the world, but chiefly worked in Pennsylvania,
U. S., and Baku, on the Caspian Sea, Russia. For more detailed information see Sadtler's " Industrial Organic-Chemistry."
By fractional distillation in closed retorts it separates into about 20 per cent, light oils, 70 per cent, burning oils, 10 per
cent, residuum.
Light Oils.
Cut off at .735 S.G.
Redistilled with special
condensing apparatus.
Burning Oil.
I.
Cymogene:
boils at
o°C.
Chiefly
c4h,
IL
Rhigolene :
boils at
I5°c.
Chiefly CsHj,
III.
Gasolene
boils at
45°C.
Chieflv
C6H14.
Low test:
Cut off at
.760 S.G *
High test:
Run till S.G.
is .930.
All burning oil (kerosene)
is treated with (a) i-J percent.
H2S04 ; (b) then washed with
water ; (£) 1 per cent, caustic
soda solution S.G. 1.085 ! {d)
washed with water; run into
settling tanks ; air currents
blown through.
45°C.
Fire test.
C10H22
to
C14H30
65°C.
Fire test.
Residuum.
If the petroleum has been distilled under low pressure,
the so-called "vacuum process," it produces reduced
oil, used for lubricating oil, and vaseline ; otherwise the
residuum is redistilled.
First
run¬
nings
returned
to
burning
oil.
Paraffin oil: agitated with
30 to 50 H2S04 ; washed
with water and caustic soda;
chilled by ice machine.
Soft wax or crude
scale paraffin :
Broken up,
melted, cooled
and pressed.
* Naphtha or benzin is between gasolene and kerosene.
Purified scale or
white wax : Wash
with benzene,
press, melt, and
filter through
bone black.
Block paraffin. Yellow Coke.
Lubricating wax.
pil.
DISTILLATION OF COAL:
Groves and Thorpes' Chemical Technology, Vol. Ill, p. 18.
Water : 3, Tar, etc. ; 4, Coke, nearly two-thirds weight of coal.
Four kinds of products, viz: 1, Gas; 2, Ammoniacal
Liquids that may be condensed.
Tar, may be distilled into
Gases and Vapors, 340 cubic
meters per ton.
f First runnings
Light oils
Carbolic oils
Creosote oils
j Anthracene oils
[ Pitch
f Water has dissolved.
May give
C6H6 Benzene.
C7Hg Toluene.
C8H10 Xylene.
\ C10H8 Naphthalene,
j C14H10 Anthracene.
L C6H5OH Phenol.
[_ Ammoniacal liquor,
Impurities separated by
purifiers.
Purified illuminating gas
contains about 40 per cent.
(_ each of H and CH4.
Carbonate
Carbamate
Sulfid
Sulfite
Thiosulfate
Sulfate
Chlorid
Cyanid
Sulfocyanid
f Ammonia.
I co2.
-{ h,s.
| CN.
I cs,.
r h
ch4
c2h4
c2h„
c6h6"
C10H
CO
N >
I h2o J
1
J- of Ammonium NH(
CnH2n+2, saturated.
l-nH2n "I
CnH2n—2 ! Unsaturated: May be absorbed
CnHan—6 j by Br or fuming, H2S04.
CnH2n-r-i2 J
( Non-illuminants.
Traces of O, CS2, etc.
7
Hydrocarbons occur in series, the successive members
differing by CH2—homologous series. Their derivatives
also form homologous series.
HOMOLOGOUS SERIES.
Hydrocarbons. Alcohols. Acids.
(General formula, (General formula, (General formula,
cnh2n+2). CnH2n+i.oh). cnhznoa).
ch4 ch3.oh ch,o2
c2h6 c2h5.oh c2h4o2
c3h8 c3h7.oh c3h602
etc. etc. etc.
The members of a homologous series are often spoken of
as the homologues of the first member or of a principal
member; thus> pentane is a homologue of methane ; pro¬
pionic acid is a homologue of acetic acid.
The two series of hydrocarbons yielding the largest
number of important compounds are the paraffin and the
benzene series. The members of the paraffin series are
found chiefly in petroleum, while benzene is a product of
coal tar obtained in the distillation of coal. (See tables on
pages 5 and 6.)
Hydrocarbon radicals, which are the " elements" of or¬
ganic chemistry, are formed by the removal of hydrogen
from the hydrocarbon:
Saturated Univalent Bivalent Trivalent
hydrocarbon. radical. radical. radical.
CH4 methane. —CH3 methyl. =CH2 methylene. =CH methenyl.
C2H6 ethane. —C2H5 ethyl. =C2H4 ethylene. =c2H3 ethenyl.
The univalent radicals of the paraffin hydrocarbons are
called alkyls; their general formula is CnH2n+I. Thus
the expression " alkyl halide" would mean a body of the
composition CnH2n+I.X, where X stands for a halogen.
Empirical or molecular formulas are of very little use in
organic chemistry, and it is important that structural and
graphical formulas be learned.
Structural formulas.
C2H5OH, or,
CH,.CH,OH
Alcohol.
CHo.O.CH,, or,
(CH3)20
Methyl ether.
Graphical formulas.
H H
II C H
H-C — C—OH °r pj >0
H H
Alcohol.
CH3>0
CH >°
Methyl ether.
The molecular formula C2H60 may mean either alcohol
or methyl ether, but in either case, written as above, there
could be no mistake.
Classification.—In inorganic chemistry we were con¬
cerned with binary and ternary compounds, including acids,
bases and salts. We shall find compounds of analogous
composition in organic chemistry.
Alkyl halides,
R.X CH3CI, methyl chloride.
Alkyl hydrates (alcohols).
R.OH C2H5.OH, ethyl hydroxide (grain alcohol).
Alk-oxides (ethers),
>0
CA>0. ethyl oxide (ether).
CH3.C<^^, acetaldehyde.
CH,
Aldehydes,
R.C<°
Ketones,
r>C—O ^^3>C=0, dimethyl ketone (acetone).
Acids,
R-C<OH CH3.C<qH> methyl carboxyl (aceticacid).
Amines,
R.NH2 C2H5.NH2, ethyl-amine.
Amides,
-O T T
, acetamide
9
This list by no means includes all the classes of organic
compounds, but is sufficient to show the relation of the
hydrocarbon radical in the constitution of substances.
Derivatives of the paraffin series and the homologues of
methane are often referred to methane as the parent sub¬
stance, or nucleus; thus, pentane C5H12 would be tetra-
CH3
i
methyl methane, H3C—C—CH3; alcohol could be called
CH3
ch3
i
hydroxy-methyl methane, H—C—OH.
I
H
It is readily understood that methane (CH4) is the simplest
of the paraffin hydrocarbons, and if an acid (for example)
were to be formed by writing the carboxyl group joined to
an R we should not have a product corresponding to the
simplest member, but the next higher. Then, in writing
the formulas of the first members of homologous series of
compounds, such as alcohols, aldehydes and acids, which
have characteristic groups of atoms, H is placed where
otherwise a hydrocarbon radical would appear.
H—CH,OH H—C<° H—C<°H
Methyl alcohol. Formaldehyde. Formic acid.
CIIj—CH,OH CHs-C<£ CH,-C<qh
Ethyl alcohol. Acetaldehyde. Acetic acid.
Some important differences between inorganic and or¬
ganic compounds may be noted.
Inorganic : Contain a relatively small number of atoms.
Many solids are not changed in composition by moderately
high temperatures. Substances containing a high propor-
IO
tion of inorganic salts leave a large amount of white ash
when burned. Many soluble substances ionize markedly.
Decomposition is not easily brought about in the majority
of cases. The principal solvents are water and the dilute
mineral acids. Identification rests almost entirely upon
qualitative determinations.
Organic: Contain a relatively large number of atoms.
When incompletely burned they carbonize, leaving a black
char, and when heated to a higher temperature they are
completely burned. In most cases when an ash is left it is
very small in quantity. Compounds which ionize at all do
so very feebly. They are easily decomposed in the majority
of cases, many of them with explosive violence; all are
combustible, yielding water and carbon dioxide. The
principal solvents are alcohol, ether, chloroform, benzene,
carbon disulphide, acetone and acetic acid.
Identification rests mostly upon quantitative determina¬
tions and certain physical characteristics, such as vapor
density, optical properties, osmotic pressure, effect in rais¬
ing the boiling point, or lowering the freezing point of
solvents ; boiling, freezing and melting points, and specific
gravity.
The determination of the molecular formula requires
several steps : i. Burn a weighed portion of the substance
to carbon dioxide and water, which are collected separately
and weighed, from which the quantity of carbon and hy¬
drogen can be found (oxygen is determined by difference)
and the per cent, of each calculated. 2. From the known
atomic mass of the elements the relative number of atoms
of each is calculated. 3. The molecular weight is estab¬
lished from the determination of the vapor density, osmotic
pressure, effect upon the boiling or freezing point of a
solvent. 4. Deduction of the molecular formula.
Some laboratory methods of general application:
The methods of finding the boiling point, freezing point
and melting point and specific gravity are probably already
II
known. The student is referred to the text book or to the
author's "Chemical Notes" for a description of how an
organic combustion is conducted.
Vapor Density.—The apparatus figured is that of Victor
Meyer. The outer jacket contains a liquid whose boiling
point is higher than the vaporizing point of the substance
under examination. The inner tube having the side-neck
delivery tube connected with a pneumatic trough receives
the substance to be volatilized. The volume of vapor re¬
sulting from the weighed portion of the substance is shown
by the displacement in the eudiometer. See text-book for
temperature and pressure correction and calculation of
density of substance.
K
Fig. 1.—Victor Meyer's
Vapor Density Appa¬
ratus.
Fig. 2. —Beckmann
freezing point ap¬
paratus.
12
Lowering of freezing point.—This operation may be
conducted in a Beckmann apparatus, a form of which is
shown in the drawing. The substance to be investigated
is dissolved and put into the inner test tube, which has a
very delicate thermometer graduated to t^q- degree. The
outer test tube contains a liquid of low freezing point,
while the battery jar contains a mixture of ice and salt.
A platinum stirrer is provided, in order that the temperature
of the whole mass in the inner test tube may be kept
uniform.
Optical properties.—The polariscope is used to find the
degree of rotation of polarized light. (All substances are
not optically active, however.)
Distillation is a very important and much used process.
A distilling apparatus is shown in figure 3.
Distillation under reduced pressure.—Many substances
of high boiling points may be distilled without decompo¬
sition under reduced pressure. Fig. 4 illustrates how
apparatus for this purpose may be set up by the use of two
distilling flasks.
13
Distillation under pressure.—The substance to be dis¬
tilled is sealed up in a hard glass tube of suitable size and
heated in a bomb furnace. Great care must be exercised
during the operation and on opening the tubes, for the
pressure is often sufficicent to shatter the glass and scatter
it with considerable force.
Distillation with steam.—Many substances are volatile
with steam, without decomposition. The apparatus is
shown in figure 5. It is essential that the distillation
flask be inclined and the steam-inlet tube bent as shown.
In this, as in other distillations, water enters the condenser
through the lower tube.
A reflux condenser is one arranged in an upright posi¬
tion, so that the condensed products may flow back into
14
the distilling flask. An air condenser is usually a glass
tube of sufficient diameter and length connected with the
distilling flask, and is used with substances of such high
boiling points that the temperature, of the air is cold
enough to effect condensation.
Filtration with suction is frequently employed for
quickly and completely removing a liquid from a precipi¬
tate. The apparatus is shown in figure 6. Suction is
easily produced by a water pump, or large aspirator bottles
may be used.
Fig. 6. —Filtration with suction. The
little cone in the funnel supports the
filter paper. The side neck of flask
receives the pressure tubing connected
with the suction pump.
15
Drying.—Crystals may (after filtering out) be partially
dried by pressing between layers of filter paper, or on a
porous porcelain plate. Complete drying may be allowed
to take place in the air, in a drying oven, or in a partially-
exhausted desiccator. For drying liquids, anhydrous
calcium chloride or fused sodium sulphate are much used.
Separation of liquids.—Two immiscible liquids may be
separated by running off the heavier one through a separa-
tory funnel or by drawing off the lighter with a pipette.
If it is desirable to separate from water a substance which
is soluble in it (liquid) it may be done by " salting out."
This consists in agitating with the mixture a salt which is
soluble in water but insoluble in the other liquid to any
extent. They may then be separated as above.
Extraction by ether.—In like manner a substance mixed
with water may be separated by agitating it with ether,
and the ether extract separated in the usual manner, after
which the ether is distilled off. Other substances, such as
carbon disulphide, benzene, chloroform, etc., are used for
extraction in suitable cases.
Caution.—In distilling ether or other volatile organic
compounds it must be remembered that their vapors are
inflammable. Ether and alcohol should never be distilled
over a free flame. A safety water bath may be employed,
or one of the forms of electric heaters used.
Decolorizing.—Colored impurities are removed from col¬
orless substances by boiling with animal charcoal.
Among the methods employed for the synthesis of or¬
ganic compounds the following are important examples:
Condensation, oxidation, reduction, halogenation, saponifi¬
cation, preparation of diazo bodies, preparation of esters,
preparation of sulphonic acids, etc.
Condensation is said to take place when a new compound
is formed from two others which jointly lose in the reac¬
tion the elements of water, hydrochloric acid, alcohol,
ammonia, or a halogen.
i6
Some condensing agents are sodium, sodium ethylate,
sodium hydroxide, sulphuric acid, phosphorus pentoxide,
zinc dust, hydrochloric acid, aluminum chloride, etc.
Oxidizing agents: Chromic acid and the bichromates,
the peroxides, the permanganates, especially potassium
permanganate, which acts in acid, alkaline or neutral so¬
lution, nitric acid, and many others.
Reducing agents: Sodium and sodium amalgam, stan¬
nous chloride, metallic iron, tin and zinc, etc.
The halogenating of organic compounds is usually
effected by the nascent halogens, their acids, or their phos¬
phorus penta- compounds.
Solvents for organic substances: Water, hydrochloric,
acid, sulphuric acid, alcohol, chloroform, ether, acetone,
benzene, carbon disulphide, acetic acid.
PRACTICAL EXERCISES.
THE PROPERTIES OF ORGANIC COMPOUNDS.
1. Char when incompletely burned. Put about 2 grams
of sugar into a test tube and heat over the Bunsen flame.
Note the brownish vapors given off. When the vapors
cease remove the black mass and examine it closely. It is
charcoal.
2. When completely burned they form C02. Finely
pulverize the mass obtained in the above experiment and
mix with it some black oxide of copper. Put into a hard
test tube connected with a bottle containing lime water.
Heat the mixture in the test tube to redness, and note that
bubbles of gas pass through the lime water, which mean¬
time turns milky.
2a. Fill another test tube half full of lime water and blow into it through
a glass tube with the breath. The lime water turns milky.
17
HALOGEN-SUBSTITUTED HYDROCARBONS.
3* Chloroform.—In a flask of not less than 2 liters'
capacity mix 50 gms. of bleaching powder and 100 c.c. of
water, and add 25 c.c. of alcohol. Connect the flask with a
condenser. Heat gently on a water bath until the action
begins ; usually it proceeds without constant application of
heat. In the receiver two layers of liquid will collect; the
lower being chloroform, the upper composed of alcohol and
water. The two layers may be separated by using a small
separatory funnel.
Agitate the chloroform with calcium chloride, to take
out the remaining water, and then distil from a small flask,
noting the boiling point of the chloroform.
4. Iodoform.—Dissolve 20 grams of potassium carbon¬
ate in 60 c.c. of water in a beaker, add 15 c.c. of alcohol
and heat to about 70° C.; then gradually add 10 gms. of
iodine. Heat gently until the brown color has all disap¬
peared. When the mixture cools, crystals of iodoform will
separate. Filter, wash and allow the crystals to dry.
Determine the melting point of the crystals, using gly¬
cerine as the bath.
The above method- of forming iodoform crystals is used as a test for the
presence of alcohol, in which case 2 c.c. of the suspected liquid may be
placed in a suitable test tube, 10 c.c. of a solution of iodine in potassium
iodide added, the whole warmed, and caustic potash solution added.
Iodoform appears upon cooling if alcohol is present.
5. Detection of halogens in organic compounds. Cal¬
cium oxide test.—Place a small piece of quick-lime into
a test tube, heat it and add two or three drops of chloro¬
form. Allow to cool, then add water and dissolve the
lime with dilute nitric acid. To the clear solution add a
few drops of silver nitrate solution. A white precipitate
will form, showing the presence of chlorine.
Chloroform when shaken with silver nitrate solution gives no precipi¬
tate. Chloroform does not give CI ions.
18
6. Beilstein's Test.—Dissolve a small quantity of iodo¬
form in carbon disulphide or moisten with alcohol. Catch
up a piece of black copper oxide in the loop of a platinum
wire and heat in the Bunsen flame until it gives no color
to it. Then moisten the copper oxide with the solution
of iodoform and again pass to the flame. The flame will
be colored green by the copper iodide.
7. Detection of Nitrogen. Lassaigne's Method.—Take
a small, hard test tube and put into it a small piece of
dried albumin and metallic sodium. Slowly bring the
tube to red heat, and while still hot plunge the end into 3
c.c. of water to break the tube and dissolve the sodium
cyanide formed. Filter the solution and wash the residue
with very little water. Add a drop of ferrous-ferric solu¬
tion and acidify slightly with hydrochloric acid. A blue
precipitate of Prussian blue will remain.
8. Will-Varrentrap's Method.—Use small pieces of dried
albumin mixed with several times their bulk of soda-lime.
Warm together in a test tube. The odor of ammonia
becomes perceptible, and a strip of moist red litmus paper
held over the mouth of the tube becomes blue.
ALCOHOLS.
Among several methods of producing alcohols are,
1. The action of moist silver hydroxide upon alkyl
halides,
C2H5C1 + AgOH = C2H5OH + AgCl.
2. The action of nitrous acid upon a primary amine,
C2H5NH2 + HNO2 = C2H6OH + N2 + H20.
3. Ethyl alcohol is produced by the fermentation of sac¬
charine liquids with the evolution of C02.
4. Methyl alcohol is made by the destructive distillation
of wood.
19
9. Ethyl Alcohol, by 2 (above).—Arrange apparatus as
shown in figure. Put 20 c.c. of glacial acetic acid into the
flask and pour through the thistle tube a solution of ethyl-
amine hydrochloride and sodium nitrite. The gas which
collects in the test tube over the pneumatic trough is nitro¬
gen. Test it. Also, test the liquid remaining in the flask
for alcohol as given under iodoform.
10. Ethyl Alcohol, by fermentation.—Make a solution
of glucose in 1,000 c.c. of water, put into a 2-liter flask and
add a piece of yeast. Connect the flask with a bottle con-
20
taining lime water, as shown in figure. The drying tube
contains small sticks of caustic soda to prevent C02 from
the air affecting the lime water. Set the whole aside for
some hours in a warm place. When fermentation is com¬
plete, as will be shown by the cessation of bubbles of gas
in the bottle of lime water, distil the liquid in the flask at
about 80 degrees, collecting about 75 c.c. of the distillate.
Test this distillate for alcohol.
11. Absolute Alcohol.—Half fill a i-liter flask with small
pieces of quick-lime and pour upon them 100 c.c. of 95 per
cent, alcohol. Allow to stand for 24 hours, then distil.
11a. Test for Absolute Alcohol.—Dry a crystal of copper sulphate in
the flame of the Bunsen burner until it loses its water of crystallization
and becomes white. Immerse it in the alcohol, which if absolute, will
have no effect upon the color of the dried crystal; but if water is present
in the alcohol the crystal will turn blue again.
ALDEHYDES.
Aldehydes are hydrocarbon derivatives containing the
r —O
group of atoms, ' They are formed by the oxida¬
tion of primary alcohols, the alcohol losing thereby 2
atoms of H.
CH3C:H2OH = CH3COH + H2O.
+ iO ;
12. Acetaldehyde.—Into a 100 c.c. flask connected with
a condenser put 5 grams of potassium bichromate, and add
slowly a cooled mixture of sulphuric acid, 5 c.c.; water,
25 c.c.; alcohol, 5 c.c. Should the action not begin spon¬
taneously heat the mixture gently. Notice the change of
color of the solution, indicating the reduction of the potas¬
sium bichromate. Keep the receiver cold. Collect the
distillate. Note the odor of aldehyde and apply the silver-
mirror test to the liquid.
13. Formaldehyde.—Burn a few c.c. of methyl alcohol
21
in contact with platinized asbestos. Notice the pungent
odor of the gas developed.
The platinum binds, when heated, atmospheric oxygen.
The vapors of methyl alcohol in passing through the
meshes of the asbestos cloth come in contact with the oxy¬
gen-carrying platinum and are oxidized.
H — C<q|J + O = HCOH + H20.
14. Silver-mirror test for aldehydes.—Add to a dilute
solution of silver nitrate a solution of ammonia until the
precipitate which is formed is nearly all dissolved. Filter,
put into a perfectly clean test tube, warm gently and then
add a few drops of a dilute solution of aldehyde. Metallic
silver will be deposited upon the sides of the test tube as a
brilliant mirror.
15. Trichloraldehyde.—Weigh out rapidly about 5 gms.
of chloral hydrate; place in a small flask, cover with con¬
centrated sulphuric acid and shake. The oily layer which
floats upon the top of the mixture is trichloraldehyde.
Water is removed by the dehydrating action of the sul¬
phuric acid. Pour the whole into a small separatory funnel
and separate the chloral from the sulphuric acid.
Now add a small quantity of water. Note that it solid¬
ifies and heat is given off (exothermic reaction).
When acetaldehyde is treated with nascent chlorine the three atoms of
hydrogen in the methyl radical are replaced by it, giving trichloralde¬
hyde, a liquid, called ordinarily chloral;
CHg.COH + 6C1 = CCI3.COH + 3HCI.
When water is added to chloral it solidifies into the substance commonly
known as chloral hydrate.
Chloral responds to the test given for aldehydes, showing
that the chlorine must have entered the methyl group,
since it has already been shown that the reducing action is
due to the double-bond group —1C<^.
22
loa. Chloroform from Chloral Hydrate.—Dissolve a particle of the
chloral hydrate thus formed in about 15 c.c. of water and add a small
quantity of caustic-potash solution. The odor of chloroform can be
detected.
ACIDS.
It has been stated that aldehydes are oxidation products
of alcohols, but they are only intermediate products; for,
if the oxidation be carried to the limit the product will be
.an organic acid.
Organic acids are hydrocarbon derivatives containing the
group CO.OH ; the general formula of the monobasic fatty
acids is CnH2n02.
16. Acetic acid from ethyl alcohol.—Put 25 c.c. of
alcohol into a beaker, add 50 c.c. of a 10 per cent, solution
of potassium permanganate and heat until the color of the
permanganate has disappeared and Mn02 has been precipi¬
tated. Acidify with sulphuric acid ; pour off the super¬
natant liquid and distil. The distillate will have the odor
of acetic acid.
Neutralize the distillate with soda solution and apply
the test for acetates.
16a. Test for Acetates.—To a dilute solution of sodium acetate add
a few drops of ferric chloride solution. A blood-red color will super¬
vene, and when the liquid is boiled a reddish-brown precipitate of ferric
acetate will be precipitated.
17. Acetic acid from acetone.—Dissolve 5 c.c. of acetone
in water and add a solution of potassium permanganate as
long as the pink color of the permanganate is destroyed.
Then filter, and acidify with sulphuric acid. Distil; the
distillate will give the odor of acetic acid. Neutralize
with soda solution and apply the test for acetates.
Acetone belongs to the class of bodies known as ketones. Whereas
aldehydes are derived from the oxidation of primary alcohols, ketones
are derived from the oxidation of secondary alcohols. Aldehydes oxi¬
dize to acids having an equal number of carbon atoms ; ketones oxidize
to acids having smaller carbon content. The general structural formula
of ketones is ^>C = 0. The formula of acetone is ^^3>C = 0 (di-
23
methyl ketone). When oxidized it produces acetic acid and formic
acid, the latter, however, being further oxidizable to carbon dioxide and
water.
ETHERS AND ESTERS.
18. Ethyl Ether .—Put 50 c.'c. each of alcohol and con¬
centrated sulphuric acid in a flask which is closed with a
stopper carrying a dropping funnel and a thermometer.
Connect the flask with a condenser, and cover the receiver
with a wet cloth to keep it cold. Heat the contents of the
flask to a temperature of about 130 degrees. When ether
begins to distil over, slowly add more alcohol through the
funnel. Collect the distillate and add an equal volume of
water; pour into a separatory funnel and agitate. When
the two liquids separate run out the water. Shake the
ether with dry calcium chloride and distil.
Small quantities of concentrated sulphuric acid are capable of trans¬
forming relatively large quantities of alcohol into ether. Williamson's
theory of etherification is expressed in the following equations :
C2H5OH + H2S04 = C2H5HSO4 + H20
C2H5OH + C2H5HS04 = (C2H5)20 + H2SO4
Care.—Remember the caution given under " Extraction with Ether."
Ethyl Acetate.—Pass dryhy drochloric acid gas into a
mixture of glacial acetic acid, 25 c.c., and absolute alcohol,
40 c.c. Heat the mixture for an hour in a flask connected
with a reflux condenser. Transfer to a fractioning flask
and distil.
CARBOHYDRATES.
The carbohydrates include the sugars, starches and cell¬
ulose, and are classified as mono-, di-, tri- and poly- saccha-
rids. The mono-saccharids are the simplest sugars; di-
and tri-saccharids split up into two and three simple sugars,
respectively; the poly-saccharids are not so easily changed
into sugars. Sugars contain an alcohol group and an alde¬
hyde group, or a ketone group, to which many of their
reactions are due.
24
Monosaccharids containing five, six, seven, etc., carbon
atoms are called pentoses, hexoses, heptoses, etc., respec¬
tively.
PROPERTIES OF THE MONOSACCHARIDS.
20. Reduce ammoniacal solutions of silver.—Use a solu¬
tion of glucose and make test with ammoniacal solution of
silver as given in 14, under aldehydes.
21. Reduce Fehling's Solution.—Use solution of glucose.
22. Resinify with caustic alkalies.—Boil a solution of
glucose with a small quantity of a solution of caustic soda.
23. Furfuraldehyde test for Pentoses.—Dissolve 3 or 4
c.c. of concentrated sulphuric acid in about 75 c.c. of water.
Put into a flask and add 10 grams of bran. Distil; the
distillate gives the odor of furfuraldehyde.
23a. Identify furfuraldehyde as follows : Add a little aniline to the
distillate, then treat with concentrated hydrochloric acid. It gives an
intense red color.
24. Hexoses. Hydrochloric test.—Boil a solution of
glucose with concentrated hydrochloric acid. A brown,
amorphous substance is deposited and laevulinic acid re¬
mains in the solution.
PROPERTIES OF SACCHAROSE.
25. Apply tests 20, 21 and 22, under monosaccharids.
The reactions are negative.
26. Inversion of Saccharose.—Dissolve three grams of
cane sugar in water and boil with dilute sulphuric acid for
about 15 minutes. Neutralize with solution of soda, and
apply tests 20, 21 and 2 2. Reactions are positive.
POLYSACCHARIDS.
27. Starch.—Agitate a small quantity of starch with
cold water, to wash it, and filter. Be sure that it is washed
well and then make with it starch paste. Use this paste
for tests 20, 21 and 22. The reactions are negative.
25
28. Conversion of starch to glucose.—Boil 30 c.c. of
starch paste with dilute sulphuric acid for about 20 min¬
utes; neutralize with soda solution and apply tests 20, 21
and 22. The reactions are positive.
THE PURIN BODIES.
Certain chemically related substances occurring in the
animal and plant world, among them uric acid, xanthine,
theobromine, caffeine, etc., are looked upon as derivatives
of the " purin ring."
N= CH HN—CO
II II
HC C—NH CO C—NH
II II >CH. | || >CO.
N—C— N HN—C—NH
Purin ring. Uric acid.
N (CH3) —CO
I I
CO C—N (CH3)
I II >CH.
N (CH3) - C N
Caffeine.
Caffeine occurs in coffee ; theobromine is found in cocoa.
The relation of urea, the principal nitrogenous constituent
of the urine, to uric acid is indicated in the following re¬
action :
C5H4N4O3 + H20 + O = (NH2)2CO + C4H2N204.
Uric acid. Urea. Alloxan.
29. Murexid test for uric acid.—Mix 5 c.c. of nitric
acid and half a gram of uric acid in an evaporating dish
and evaporate over a water bath almost to dryness ; treat
the residue with ammonium hydroxide. It will give a pur¬
ple-red color.
30. Murexid test for caffeine.—Apply test as for uric
acid, using caffeine in the place of uric acid.
26
CLOSED-CHAIN HYDROCARBONS.
The closed-chain hydrocarbons differ from the open
chain in several respects.
Open chain.
Not easily acted upon by
nitric or sulphuric acids.
Not affected ordinarily by
oxidizing agents.
Hydroxyl-derivatives are of
a basic character.
Closed chain.
Easily form nitro-deriva-
tives with nitric, and sul-
phonic-derivatives with
sulphuric, acid.
The homologues of benzene
are oxidizable.
Hydroxyl-derivatives are of
an acid character.
ACTION OF NITRIC ACID.
31. Nitrobenzene.—Put into a flask a mixture of 1 part
nitric acid and 2 parts (by volume) of sulphuric acid.
Slowly add about 1 part of benzene. Keep the flask cold
with running water. When the benzene has dissolved
pour the mixture into water. The heavy nitrobenzene
will sink to the bottom. Separate from the upper layer
and notice the odor of bitter almonds.
ACTION OF SULPHURIC ACID.
32. Benzene-mono-sulphonic acid.—Gradually add 5 c.c.
of benzene to 10 c.c. of fuming sulphuric acid. Heat
gently for a few minutes, and then pour the reaction mix¬
ture into about 30 c.c. of cold water. Stir in some common
salt until fumes of hydrochloric acid are given off. When
cold, crystalline plates of sodium benzene-sulphonate, a
salt of benzene-mono-sulphonic acid, will separate.
Friedel and Craft's Reaction.—This is one of the most important
synthetic reactions and is peculiar to the benzene series. By its use a
great many compounds have been built up easily which probably other¬
wise would not yet have been synthesized. The synthetic agent is
aluminum chloride.
27
33* Triphenyl-methane.—Perform this experiment un¬
der the hood. Make a mixture of i gram of aluminum
chloride and 5 c.c. of benzene ; then gradually add a little
chloroform. Hydrochloric acid is given off vigorously, in
the meantime tri-phenyl-methane is formed.
(C6H5)
3C,H# + CHCI3 = H—C—(C6H5) + 3HCI.
(C6H5)
Triphenyl methane gives rise to many important dyes, e. g., methyl
violet, aniline blue, malachite green, rosaniline, magenta, rosolic acid,
etc.
34. Oxidation of side chains.—Heat 2 c.c. of toluene
with a solution of potassium permanganate until the purple
color is discharged. The precipitate is manganese diox¬
ide. Filter, acidify with sulphuric acid, and allow to cool.
Crystals of benzoic acid will separate.
BENZENE DERIVATIVES.
Phenol is hydroxy-benzene, that is, benzene in which an atom of hy¬
drogen has been substituted by hydroxyl. It is commonly known as
carbolic acid.
35. Trinitrophenol.—Cautiously drop into 10 c.c. of
nitric acid about one c.c. of phenol, meantime shaking the
flask, then heat to boiling. Picric acid is precipitated
upon cooling and crystallizes from hot water in yellow,
needle-like crystals.
Compare this action with the action of an acid on the hydroxyl-deriv-
ative of an open-chain hydrocarbon, for example, the action of nitric
acid upon amyl alcohol. The result would be the formation of an ester,
amyl nitrite, by the replacement of the OH of the alcohol by the radical
of the acid. Here the nitro group replaces H of the nucleus, giving tri-
nitro-phenol—picric acid.
36. Amino-Compounds. Anilin.—Put into a flask 10 c.c.
of nitro-benzene and add 30 c.c. of hydrochloric acid. Add
to this 15 grams of powdered tin, in portions of about 1
28
gram at a time. After each such addition shake the flask
and immerse in water to keep it cool. When the odor of
nitro-benzene is no longer perceptible add a solution of
caustic soda. Distil with steam, as shown in figure 5. Ex¬
tract the turbid distillate with ether; separate in the sepa-
ratory funnel; dry the ethereal extract with sticks of
caustic potash; evaporate the ether and then distil from
a small fractioning flask over a free flame.
Anilids are salts of anilin in which an atom of H in the amino group is
replaced by an acid radical. Acetanilid is such a salt, in which the
acetic acid radical is substituted.
37. Acetanilid.—Boil together in a flask fitted with a
reflux condenser equal volumes of anilin and glacial acetic
acid (not more than 15 c.c. of each). The operation will
require several hours. The mixture when cold deposits
crystals of acetanilid.
Benzaldehyde.—Benzaldehyde responds to the tests for
aldehydes already learned under open-chain derivatives.
38. Make the silver-mirror test, using 2 drops of benzal¬
dehyde.
39. Benzaldehyde oxidizes to benzoic acid. Heat a little
benzaldehyde with a solution of potassium permanganate.
Should the color of the permanganate persist after the odor
of the benzaldehyde has disappeared, add a drop or two of
alcohol—only enough to discharge the color. Filter, acidify
and allow to cool. Benzoic acid is precipitated.