CHEM10007 Lecture Notes - Lecture 26: Adolf Von Baeyer, Inorganic Chemistry, Coal Tar
12 Jun 2018
School
Department
Course
Professor
LECTURE 26
ORGANIC CHEMISTRY - ALKANES
CHAPTER 14 - ORGANIC CHEMISTRY 1
HISTORY OF ORGANIC & INORGANIC COMPOUNDS
•The misleading term organic is a relic of the early days in the development of chemistry, during
which chemical compounds were divided into two classes depending on their origins; organic and
inorganic compounds. Inorganic compounds were those obtained from minerals, while organic
compounds were those obtained from vegetable or animal sources; living organisms.
•The Swedish chemist Torbern Bergman was the first to express these differences in the properties
of substances obtained from living sources and those obtained from minerals in 1750. This lead to
the Vital Force Theory in 1770.
•According to the Vital Force Theory, differences in behaviour between organic and inorganic
compounds, arise because organic compounds contain a peculiar Vital Force as a result of their
origins from living organisms. Thus, chemists believed that organic compounds could not be
prepared or manipulated in the laboratory, as could inorganic compounds.
•However, in 1816 the French chemist Michel Chevreul converted animal fat into a mixture of
soap and glycerin by treatment with sodium hydroxide (a process known as saponification). He
then showed that the soap obtained upon acidification
could be converted into a mixture of fatty acids, which
could be separated.
•For the first time, one organic compound (fat) had
been converted into others (fatty acids and glycerin)
without the help of an outside Vital Force.
•Similarly, in 1828 Friedrich Wohler showed that it
was possible to convert the inorganic compound
Ammonium Isocyanate, into the previously known
organic compound, Urea by heating.
•By the 19th century, the weight of evidence was mounting against the Vital Force Theory, and in
1848 William Brande (Lecturer in Chemistry, London) published the statement:
•“No definite line can be drawn between organic and inorganic chemistry – any distinctions must
for the present be merely considered as matters of practical
convenience. The same principles that explain the simplest
inorganic compound also explain the most complex
organic molecules. The only distinguishing characteristic
of organic chemicals is that all contain carbon”.
•W. H. Perkin, as an 18 year old student, accidentally
discovered a simple way to prepare a deep purple dye
which he called Mauveine, from the extracts of coal tar.
•This was used commercially for dyeing silk garments and
was the beginnings of the multinational chemical company ICI.
•1868 Saw the synthesis of the orange-red dye Alizarin, which was
used for dyeing wool.
•In 1860 Adolf Von Baeyer completed the first laboratory synthesis
of Indigo, later, in 1905 Adolf Von Baeyer was awarded the Nobel
prize in Chemistry for his contributions to Organic Chemistry.
•1887-1914 Saw the commercial synthesis of a variety of organic
compounds:!
Perfumes, novocaine, aspirin, salvarsan (An Arsenic
containing organic compound – the so-called ‘magic
bullet’ for treatment of syphillis), and explosives.
•Since 1920 – antibiotics, vitamins, hormones, anti-
cancer drugs, fertility agents, polymers, insecticides,
agricultural chemicals and pharmaceuticals – all organic compounds- have been synthesised.
•Organic Chemistry is the chemistry of carbon compounds, both from living systems, and
synthesized in the laboratory. They are not exclusive to nature, but can be prepared and
manipulated in the laboratory. However natural systems do remain one the most important
source of organic compounds.
SOURCES OF ORGANIC COMPOUNDS
•First prepared from inorganic compounds in living systems during photosynthesis where
‘inorganic’ carbon (CO2) (H2O) and light) become incorporated into plants and some
microorganisms. Plants and animals provide us directly with useful chemicals in the form of soap,
food, cotton, flax, sugar, rubber, essential oils, perfumes, flavourings and drugs, while
microorganisms provide us with anti cancer agents, antibacterials (e.g. penicillin from mould),
antifungal agents, and ethanol from yeast.
•The largest source of organic chemicals comes from the products of diagenesis of plants over
millions of years.
•The main 4 sources of organic compounds are:
•Crude oils; petrochemicals which provide the essential raw materials for chemical industry (e.g.
polymers, textiles and pharmaceuticals) and as a fuel.
•Plants and animals; soap, sugar, rubber, perfumes, flavourings, food
•Microorganisms; antibiotics, anticancer compounds, ethanol.
•Coal tar; benzene, alkyl benzenes, naphthalene, anthracene, phenanthrene, phenols and other
aromatic compounds.
•Organic chemistry is a very rich and diverse area of chemistry. There
are well over 13 x 10^6 known chemical compounds of all
types. This is growing at a rate of ca. 600 p.a. Of these
some 30,000,000 compounds 98% are carbon compounds.
What is so special about carbon that allows it to form such
a large number of stable compounds?
•1. The carbon-carbon bond, which is the backbone of
organic compounds is strong, therefore organic
compounds are stable.
•2. Carbon readily forms stable multiple bonds with
itself and with other elements.
•Single bonded C-C, bond distance 1.54 Å;
•Double bonded C=C, bond distance 1.33 Å
•Triple bonded Carbon CC, bond
distance 1.06 Å.
•Å = 10^-10 meters.
•3. Geometry about the carbon atom
can be linear, trigonal or tetrahedral.
•Thus, there is a seemingly limitless
number of possibilities for carbon
compounds.
•This complex area of chemistry is made
easier to study by classifying organic
compounds into different groups of
Geometry about the C atom
Document Summary
History of organic & inorganic compounds: the misleading term organic is a relic of the early days in the development of chemistry, during which chemical compounds were divided into two classes depending on their origins; organic and inorganic compounds. Ammonium isocyanate, into the previously known organic compound, urea by heating: by the 19th century, the weight of evidence was mounting against the vital force theory, and in. 1848 william brande (lecturer in chemistry, london) published the statement: no definite line can be drawn between organic and inorganic chemistry any distinctions must for the present be merely considered as matters of practical convenience. The same principles that explain the simplest inorganic compound also explain the most complex organic molecules. The only distinguishing characteristic of organic chemicals is that all contain carbon : w. They are not exclusive to nature, but can be prepared and manipulated in the laboratory. However natural systems do remain one the most important source of organic compounds.
