PART I. ELEMENTARY
G. S. TURPIN, M.A. (CAMB.), D.Sc. (LOND.)
PRINCIPAL OF THE TECHNICAL SCHOOL, HUDDERSFIELD
MACMILLAN AND CO.
All rights reserved
BY MACMILLAN AND CO.
XortoooB J9rfss :
Berwick & Smith, Boston, U.S.A.
1. THE ANALYSIS OF ORGANIC BODIES . . . i
2. EMPIRICAL AND MOLECULAR FORMULAE . . .12
3. HYDROCARBONS OF THE METHANE SERIES . . 19
4. OLEFINES AND ACETYLENE. . . . .28
5. HALOID DERIVATIVES . . . . -37
6. THE ALCOHOLS . . . . . -44
7. ETHEREAL SALTS Ethers Mercaptan . . -55
8. ALDEHYDES AND KETONES . . . . .61
9. THE FATTY ACIDS . . . . . .68
10. ACETYL CHLORIDE AND ACETIC ANHYDRIDE . . 79
11. THE AMINES . . . . . .82
12. THE AMIDES AND AMIDO-ACIDS . . . .88
13. ALKYL COMPOUNDS OF PHOSPHORUS, ARSENIC, SILICON,
' AND THE METALS . . . . .92
14. GLYCOL AND ITS DERIVATIVES. SUCCINIC, MALIC, AND
TARTARIC ACIDS . . 99
15. LACTIC AND CITRIC ACIDS. . . . 106
16. THE ALLYI, COMPOUNDS . . . . . no
17. GLYCERINE AND ITS COMPOUNDS . . . . 115
18. THE CARBOHYDRATES . . . .119
19. UREA AND URIC ACID . . . . .128
20. THE CYANOGEN COMPOUNDS . . . . 131
THE ANALYSIS OF ORGANIC BODIES
Province of Organic Chemistry. Up to the beginning
of this century it was generally supposed that all chemical
substances might be sharply divided into two classes, according
as their formation was, or was not, possible without the aid of
living organisms ; those compounds which had been obtained
only from some animal or plant were called organic bodies,
and the action of the mysterious " vital force " was believed
to be necessary for their formation. In 1828, however, the
German chemist Wohler prepared urea, a typical organic
substance, from inorganic materials by a chemical reaction of
very simple character, and thus broke down the separation
which up to that time had been maintained between inorganic
and organic substances ; but, as a matter of convenience, we
still retain the name organic chemistry for a department of the
science which is concerned with the chemistry of the com-
pounds of two elements, carbon and hydrogen, and their
numerous derivatives. Amongst these are included nearly all
the substances formed by the complicated chemical processes
lying at the base of life, whether animal or vegetable, as well
as a still larger number which have been prepared artificially
by the simple processes of the laboratory. Many compounds
obtained, in the first place, from animals or plants have been
2 ORGANIC CHEMISTRY CHAP.
afterwards manufactured in the laboratory, and chemists have
good reason to believe that in the future there will be no
single substance known whose formation cannot be brought
about by ordinary chemical reactions.
The distinction between organic and inorganic chemistry
is, then, merely a convenient division of the vast material of
the science, and organic chemistry may be defined as the
chemistry' of the hydrocarbons and their derivatives.
Reasons for the separate Study of Organic Chem-
istry. The reasons which make it convenient still to
maintain an artificial separation between inorganic and organic
chemistry are chiefly the immense number of organic com-
pounds known a number which receives additions every
day and the different character of the problems presented to
us by them as compared with the much less numerous and
comparatively simple inorganic bodies. In organic chemistry
the most important points claiming our attention are the
grouping of the atoms present in each compound, and the
influence of this grouping on the properties of that compound.
We shall find cases where the molecules of two different
substances contain exactly similar atoms, and in the same
number, but the different arrangement of the atoms in the two
molecules produces bodies with markedly different properties.
The name isomerism is given to this phenomenon. Cases
of it are almost unknown in inorganic chemistry, but are
extremely frequent in organic chemistry ; see p. 24 for a further
account of it.
On the other hand, we often find a series of organic com-
pounds, all of different composition, but possessing very
similar properties, owing to the presence in their molecules of
the same group of atoms ; prominent instances of this are
furnished by the homologous series, of which more is said
on p. 21.
Elements present in Organic Compounds. Every
organic compound contains carbon, and in nearly every one
hydrogen is also found ; the other elements may any of them
occur, but those more frequently found are nitrogen, oxygen, the
halogens, sulphur, and phosphorus.
The carbon, hydrogen, and nitrogen are most satisfactorily
detected by heating the substance with copper oxide in a
hard-glass tube ; the organic material is burned up by the
oxygen of the copper oxide, some of which is reduced to
metallic copper, and the products of the combustion are
carbon dioxide, water, and nitrogen gas. If no water is
produced by the combustion, then no hydrogen was present in
the substance examined, and if no nitrogen be given off, that
element was similarly absent from the material employed.
EXPT. i. Take a piece of ordinary combustion tubing closed at one
end ; introduce into it (a) enough dry cupric oxide (best granulated) to fill
about three inches of the tube ; (6) then about one gram of sugar ; (c) and
lastly, fill the tube nearly to the open end with more granulated copper
oxide. Close the open end of the tube with a well-fitting rubber stopper,
through which passes a piece of glass tubing carrying a small bulb, and
connect this with two small wash-cylinders, of which the first contains
lime-water (better, baryta water), and the second strong solution of
FIG. i. Apparatus for Experiments i and 2.
Heat the tube carefully in a combustion furnace, or over a row of four
Bunsen burners ; first applying heat at the two ends of the tube, and
when these have become just red-hot, turning up gradually the two
middle burners. Notice the production of water and CO 2 , and that no
nitrogen escapes from the second wash-cylinder after the air has been all
EXPT. 2. Repeat, using urea instead of sugar. Notice the large
amount of gas evolved which is not absorbed by the caustic soda. Urea
contains nearly fifty per cent of nitrogen.
When proper precautions are applied this method of
combustion with copper oxide enables us to determine with
considerable accuracy the amounts of carbon, hydrogen, and
nitrogen present in any organic substance. The carbon and
hydrogen are usually determined by one experiment, the
nitrogen by a second.
ESTIMATION OF CHAP.
Quantitative Determination of Carbon and Hydro-
gen. There are several variations in the details of the
experiment as adopted by different chemists ; we shall describe
only one plan of work.
A piece of hard-glass tubing, long enough to project about
an inch from each end of the combustion furnace, is connected
at the one end with a
^^ tube, through which
c^|g- c fanrR~^-^rr-Tip'=' e j t h er a | r or oxygen
in each case dry and
FIG. 2. Flask fitted with CaCl 2 tube, in which the r frnm rarhrm rlinv
copper oxide is allowed to cool after being dried f
by heating to redness. ide may be supplied
at will ; and at the
other end, with a U tube containing lumps of porous CaCl 2 ,
to absorb and retain the water produced in the combustion,
followed by a potash apparatus (Fig. 5), which similarly
absorbs the carbon dioxide.
About two-thirds of the combustion tube at the end nearer
the absorbing tubes is filled with granulated copper oxide,
kept in position by two plugs of copper gauze ; behind this is
a "boat" of porcelain or platinum, into which about one-fifth
FIG. 3. Tube arranged for combustion in a current of Oxygen ; the CaCl2 tube
only is shown attached.
of a gram of the substance to be analysed has been accurately
weighed ; and then follows a longer plug of oxidised copper
gauze, whose object is to prevent any backward diffusion of
the products of the combustion.
The copper oxide having been previously thoroughly dried,
the portions of the tube on either side of the boat are first
raised to a dull red heat, and the actual combustion is then
begun by carefully and gradually applying heat to the
substance in the boat, while a very slow current of pure air is
passed through the apparatus. Towards the end oxygen is
introduced in place of air, with the object of burning up any
carbonaceous residue that may have been left in or about the
CARBON AND HYDROGEN
boat, and then air is again passed, in order to sweep along
any C(X or oxygen that may be in the tube or absorbing
apparatus. (Oxygen is heavier than air, hence the need of
leaving the absorbing apparatus filled with air at the end, as
at the beginning, of the combustion.)
The CaCl., tube and the potash apparatus were, of course,
weighed before the combustion was commenced ; they are
weighed again after it is over, and the increase of weight
FIG. 4. U-tube filled with CaClo for
absorbing the water produced in the
FIG. 5. Potash apparatus for
absorbing the COj-
gives the amount of water and of carbon dioxide produced by
burning a known weight of the substance. An example will
best illustrate how the percentage of carbon and of hydrogen
present in the substance may be calculated.
Example. 0.2386 gram of a substance gave 0.4879 gram CO 2 and
0.0870 gram HoO.
The percentage of carbon = 100 x '- x = 55.76,
for .4879 gram COo contains .4879 x gram of carbon.
The percentage of hydrogen = 100 x - - x - = 4.05.
Quantitative Determination of Nitrogen. There
are several methods in use, but the only one which is appli-
cable to all organic bodies alike is that of Dumas, in which the
substance is burned with copper oxide in an atmosphere of
carbon dioxide, and the liberated nitrogen collected over a
solution of caustic potash and measured.
Fig. 6 represents the apparatus used. The combustion tube
is filled with (a) a six-inch length of granulated oxide ; (b) a
mixture of a known weight of the substance with powdered
copper oxide ; (c) six or eight inches of granulated oxide ;
(d) a spiral of copper gauze. It is connected at one end
with an apparatus for evolving carbon dioxide, from which,
first of all, a steady stream of the gas is passed for at least
half an hour, until the air is entirely driven out from the
tube. During this time the granulated oxide on either side
of the mixture (b) may be cautiously heated. When the air
is expelled the collecting apparatus is filled to the tap with
FIG. 7. Apparatus
for evolving a
steady stream of
CC>2 by the action
FIG. 8. Apparatus in which the Nitrogen
is collected over potash solution.
potash solution by raising the bulb, the tap is closed, and
the stream of CO 2 stopped ; the copper spiral is now heated
to redness and the combustion proceeded with. At the end
more CO., is passed, in order to sweep out any nitrogen from
the tube and carry it into the measuring apparatus.
It is necessary to mix the substance with powdered CuO,
as otherwise the combustion would not be complete in the
atmosphere of CO 2 . The object of the copper spiral is to
reduce any oxides of nitrogen that might be evolved, and one
must also be used in determining the carbon and hydrogen in
a nitrogenous body.
An example will illustrate the method of calculation. The
work is much simplified by the use of tables which have been
specially prepared for the purpose.
Example. 0.2258 gram gave 28.3 c.c. moist nitrogen, measured at
9.5 C. and 765.5 mm.
The only difficulty is in calculating the exact weight of the nitrogen.
It is measured over strong potash solution, whose vapour pressure at
9. 5 C. is found in the tables as 7. i mm. ; the pressure of the nitrogen is
therefore 765.5 7. i = 758.4 mm. Its volume (measured dry) at o and
760 mm. would therefore be
28. 3 x . X = 27. 3 c.c.
and its weight 27.3 x .0000896 x 14 = . 03424 gram (i litre H weighs
.0896 gram at normal temperature and pressure). The percentage of
.03424 x 100
nitrogen is therefore =15.16.
Many organic bodies containing nitrogen evolve ammonia
when heated with soda lime (some, however, give off only
part, and others none, of their nitrogen in the shape of
ammonia), and on this plan it is possible in many cases to
detect the presence of nitrogen, and estimate its amount. In
the quantitative process (known by the names of Will and
Varrentrapp) the liberated ammonia is absorbed by means of
dilute hydrochloric acid placed in a bulb tube of suitable
construction. The amount of the ammonia is ascertained by
estimating how much hydrochloric acid has been neutralised
This method has fallen into disuse, having been replaced
by one due to Kjeldahl, which is applicable in all cases where
Will and Varrentrapp's can be used, and is much more
ESTIMATION OF CHAP.
convenient. Kjeldahl decomposes the substance by heating it
with concentrated sulphuric acid and addition of a little
potassium permanganate. Under this treatment the nitrogen
of the organic body is in many cases converted into ammonia,
which is afterwards liberated by addition of caustic soda,
distilled off and collected in a measured volume of dilute acid
of standard strength. The calculation is precisely similar,
whether Will's or KjeldahPs method be adopted.
FIG. 9. One form of apparatus for the second part of Kjeldahl's process ; the
ammonia is boiled off and absorbed by standard acid.
Example. 1.2350 gram of a substance was treated by Kjeldahl's
method, and the ammonia produced collected in 25 c.c. of dilute hydro-
chloric acid of normal strength ; at the end of the distillation it was found
that 15.3 c.c. of normal soda solution were needed to neutralise the excess
of acid which still remained uncombined.
The amount of ammonia produced was, therefore, sufficient to
neutralise 9.7 c.c. ( = 25 15.3) of normal acid; that is to say, it was
equal to the amount contained in 9.7 c.c. of a normal solution of
ammonia. Such a solution contains 17 grams of NH 3 (molecular weight
= 17) in a litre, and in 9.7 c.c. there would be 17 x 9.7 milligrams NH 3 ;
of this 14x9.7 mgms. are nitrogen, and therefore the percentage of
. 14 x. 0097
nitrogen is xioo = u.o.
Detection and Quantitative Estimation of the
Halogens. Organic substances containing chlorine, bromine,
or iodine, do not, as a rule, react at all readily with silver
nitrate ; it is necessary first to decompose the organic matter,
for which purpose either of the two following methods may
be used :
(a) Carius's method employs nitric acid as the oxidising
agent. About .2 gram of the substance is intro-
duced along with i or 2 c.c. of fuming nitric acid
and a crystal of silver nitrate into a tube of stout
glass ("pressure" tubing of fairly soft glass with
walls 2 to 3 mm. thick is the most convenient)
about 40 cm. long and 2 cm. external diameter.
The open end of the tube is next carefully heated
in the blow-pipe flame until the walls have thick-
ened considerably at the heated spot, and then
cautiously drawn out into a thick-walled capillary
tube, which is finally sealed. The tube so prepared
is heated in a specially designed and very strong
air bath (or " cannon ") to a temperature which
varies, according to the character of the substance
to be analysed, from 150 to 300 C. for one or
two hours. The tube must be allowed to cool
inside the "cannon," and even \vhen cold contains
gases (carbon dioxide and oxides of nitrogen)
under such considerable pressure that its opening
can only be safely effected by heating the capillary
tip of the tube in a flame until the softened glass ,
gives way before the internal pressure, and allows glass tube
the compressed gases to escape. method""^
The silver chloride (or bromide or iodide) analysis.
formed is washed out from the tube with distilled
water, collected on a filter, washed, dried with the needful
precautions by heating to fusion in a porcelain crucible, and
(b) The alternative or dry method consists in heating the
substance with pure lime in a combustion tube heated in an
ordinary combustion furnace. The calcium chloride (or bromide
or iodide) produced is estimated in the usual way by precipita-
tion with silver nitrate.
Example. (The calculation is precisely similar in both cases.) .1638
gram of the substance yielded .0953 gram AgCl.
The percentage of Cl is therefore, since 145.4 parts of AgCl contain
37.4 of chlorine,
of the halogens
can most certainly be
FIG. ii. Air-bath for Carius's method.
accomplished by applying roughly one of the quantitative
above ; but more
conveniently by Beil-
stein's plan, in which
a little copper oxide,
supported in a small
loop at the end of a
platinum wire, is
heated in a Bunsen
flame until this is no
longer coloured, and
is then used to con-
vey a small portion
of the substance
adhering to the
copper oxide into the flame. If chlorine is present copper
chloride will be produced, and its vapour will give the char-
acteristic blue and green flame of copper.
Sulphur and Phosphorus may be estimated by heating
the substance with fuming nitric acid in a sealed tube (Carius's
method ; see under Halogens). The sulphuric acid formed
may be determined as barium sulphate, the phosphoric acid as
In the case of the less volatile substances, a dry method
may conveniently be used, in which fusion in a silver dish with
solid potassium hydrate, and gradual addition of potassium
nitrate, is employed to effect the oxidation of the sulphur to
Example. .21-78 gram of the substance gave .2586 gram of BaSO 4 .
The percentage of sulphur is therefore, since 233 parts of BaSO 4
contain 32 parts of S,
x x 100
SULPHUR AND PHOSPHORUS
The qualitative recognition of sulphur or phosphorus in an
organic body may be effected by heating the dry substance
with a little metallic sodium. If sulphur is present, sodium
sulphide will be formed, and may be detected by the evolution
of H S on addition of water and an acid, or by the use of
sodium nitro-prusside, which gives an intense violet colouration
with a trace of soluble sulphide. In the case of phosphorus,
sodium phosphide (or if, as is advantageous, aluminium filings
be employed, aluminium phosphide) is formed, from which
the dampness of the breath is sufficient to evoke the character-
istic smell of hydrogen phosphide.
Oxygen. There is no convenient method known for the
detection or estimation of oxygen in a compound. Its amount
is determined by difference, i.e., by subtracting the percentages
of all the other elements present from 100, and taking the
remainder to represent the percentage of oxygen.
QUESTIONS ON CHAPTER I
1. Describe carefully the methods you would use for the quantitative
estimation of the elements present in urea.
2. Explain how the percentage of nitrogen in an artificial manure can
be readily determined.
3. Oil of mustard contains carbon, hydrogen, nitrogen, and sulphur.
How would you prove that these elements and no others are present in it?
4. How is the percentage of chlorine in sodium chloride determined,
and how must the method be modified in order to apply it to organic
substances containing chlorine ?
EMPIRICAL AND MOLECULAR FORMULAE
THE Empirical Formula of a substance is the simplest
formula which represents the results of analysis, and is
calculated from these in the following way : Divide the per-
centage of each element by the corresponding atomic weight ;
find the smallest whole numbers standing in the same ratio as
the quotients thus obtained, and you will have the indices of
the formula. This is best illustrated by examples :
A substance contains the percentages given below; to. find its empirical
C = 4O per cent.
O = 53-33
Then C = ^=.
and as these numbers are in the ratio 1:2:1, the empirical formula of the
substance is CH^O.
In the above example we have taken not the results of
actual analysis, but the theoretical percentages. In calculating
from the experimental numbers always more or less
inaccurate we may sometimes have to choose between two
or more formulae which agree about equally well with the
analvtical results. In such cases it should be remembered
MOLECULAR FORMULA 13
that we usually find in a properly conducted analysis : (i.)
about .1 or .2 per cent too little of carbon, unless halogens
are present; (ii.) about .2 per cent in excess of hydrogen;
and (iii.) about .2 or .3 per cent in excess of nitrogen (by
The chief causes of these slight errors are : (i. ) loss of COj through
incomplete absorption; (ii. ) trace of moisture in the copper oxide
employed ; (iii. ) presence of traces of air in the combustion tube and in
the CO 2 used for expelling air from the tube.
The Molecular Formula represents not merely the
results of analysis, but is also in agreement with whatever
information we are able to obtain by application of
Avogadro's hypothesis or otherwise- as to the molecular
weight of the compound. It is sometimes identical with the
empirical formula, but is often a multiple of it, and the ratio
is ascertained by a molecular weight determination. This
may usually be effected by some one of the following methods.
I. Chemical Methods are not of very general application,
and give only a minimum value of the molecular weight.
Their principle is that in substituting one element (or radical)
for another, we cannot replace a fraction of an atom. If, then,
in a particular compound it is found possible to replace, say,
one quarter of the hydrogen in it by some other element,
without affecting the other three - fourths, we conclude that
there were four atoms (or a multiple of four) in the molecule
of that compound.
EXAMPLE I. The analysis of acetic acid leads to the
empirical formula CH 2 O ; but there are numerous derivatives
of the acid whose analysis shows that one-fourth only of the
hydrogen has been replaced, such as monochloracetic acid
C 2 H 3 C1O 2 , silver acetate C^H^AgOg, etc. Hence the molecu-
lar formula must contain four atoms of hydrogen, and is
written C H 4 O.,.
EXAMPLE II. Another substance, also possessing the same
empirical formula CH,,O, is dextrose ; but this compound
yields a derivative in which analysis shows that five-twelfths
of the hydrogen have been replaced, while seven-twelfths are
left ; there must then be not fewer than twelve atoms of
hydrogen in the molecule, and its formula is put as CgHj.,0...
II. The Physical Methods much more convenient,
and in some respects more decisive, than the chemical depend
upon the " law of Avogadro," or upon its extension by Van't
HofT to the case of dilute solutions.
As applied to gases the law states that at a given tempera-
ture the pressure of a gas is proportional to the number oj
molecules in unit volume. If now we find the weights of equal
volumes (at the same temperature and pressure) of two gases,
we have the weights of equal numbers of molecules of the
gases, and the ratio of these weights will give the ratio of the
molecular weights. The vapour density of a substance is
the ratio obtained by comparing the weight of a volume of
that body (in the gaseous state) with the same volume of
hydrogen at the same temperature and pressure. Admitting
the weight of the hydrogen mole-
cule to be 2, in accordance with
the formula H 2 , it follows that,
when hydrogen is taken as the
^ standard, the molecular weight of
^>^ ^\ an y substance is twice its vapour
density. In determining this we
do not need to measure both
vapour and hydrogen under iden-
tical conditions, as by the help
of Boyle's and Charles's laws we
can easily reduce the results ob-
tained to what they would be
under the same pressure and tem-
perature. The experimental pro-
cesses which may be used for
determining vapour densities are
many, but the following are the
most important :
FlG.i2.-Apparatusfordetermining (a.) Victor Meyer's Method