Organic chemistry

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Structure of the methanemolecule: the simplest hydrocarbon compound.

Organic chemistry, sometimes abbreviated as "OChem", is a subdiscipline

within chemistry involving thescientific study of the structure, properties,
composition, reactions, and preparation (by synthesis or by other means)
of carbon-based compounds, hydrocarbons, and their derivatives. These
compounds may contain any number of other elements,
including hydrogen, nitrogen, oxygen, the halogens as well
asphosphorus, silicon and sulfur.[1][2][3]
Organic compounds are structurally diverse. The range of application of
organic compounds is enormous. They form the basis of, or are important
constituents of many products
(plastics, drugs, petrochemicals,food, explosives, paints, etc.) and, with very
few exceptions, they form the basis of all earthly lifeprocesses.

History
Main article: History of chemistry

Friedrich Wöhler

In the early nineteenth century, chemists generally believed that

compounds obtained from living organisms were too complex to be
obtained synthetically. According to the concept of vitalism, organic matter
was endowed with a "vital force". They named these compounds "organic"
and directed their investigations toward inorganic materials that seemed
more easily studied.[citation needed]
During the first half of the nineteenth century, scientists realized that
organic compounds can be synthesized in the laboratory. Around
1816 Michel Chevreul started a study of soaps made from
various fats and alkalis. He separated the different acids that, in
combination with the alkali, produced the soap. Since these were all
individual compounds, he demonstrated that it was possible to make a
chemical change in various fats (which traditionally come from organic
sources), producing new compounds, without "vital force". In 1828 Friedrich
Wöhler produced the organic chemical urea (carbamide), a constituent
of urine, from the inorganic ammonium cyanateNH4OCN, in what is now
called the Wöhler synthesis. Although Wöhler was always cautious about
claiming that he had thereby destroyed the theory of vital force, historians
have looked to this event as the turning point.
In 1856 William Henry Perkin, trying to manufacture quinine, again
accidentally manufactured the organic dye now called Perkin's mauve. By
generating a huge amount of money this discovery greatly increased
interest in organic chemistry.
The crucial breakthrough for organic chemistry was the concept of
chemical structure, developed independently and simultaneously
byFriedrich August Kekule and Archibald Scott Couper in 1858. Both men
suggested that tetravalent carbon atoms could link to each other to form a
carbon lattice, and that the detailed patterns of atomic bonding could be
discerned by skillful interpretations of appropriate chemical reactions.
The history of organic chemistry continued with the discovery
of petroleum and its separation into fractions according to boiling ranges.
The conversion of different compound types or individual compounds by
various chemical processes created the petroleum chemistry leading to the
birth of the petrochemical industry, which successfully manufactured
artificial rubbers, the various organic adhesives, the property-modifying
petroleum additives, and plastics.
The pharmaceutical industry began in the last decade of the 19th century
when acetylsalicylic acid (more commonly referred to as aspirin)
manufacture was started in Germany by Bayer. The first time a drug was
systematically improved was with arsphenamine (Salvarsan). Numerous
derivatives of the dangerously toxic atoxyl were examined by Paul
Ehrlich and his group, and the compound with best effectiveness and
toxicity characteristics was selected for production.
Although early examples of organic reactions and applications were
often serendipitous, the latter half of the 19th century witnessed highly
systematic studies of organic compounds. Beginning in the 20th century,
progress of organic chemistry allowed the synthesis of highly complex
molecules via multistep procedures. Concurrently, polymers and enzymes
were understood to be large organic molecules, and petroleum was shown
to be of biological origin. The process of finding new synthesis routes for a
given compound is called total synthesis.Total synthesis of complex natural
compounds started with urea, increased in complexity
to glucose and terpineol, and in 1907, total synthesis was commercialized
the first time by Gustaf Komppa with camphor. Pharmaceutical benefits
have been substantial, for examplecholesterol-related compounds have
opened ways to synthesis of complex human hormones and their modified
derivatives. Since the start of the 20th century, complexity of total
syntheses has been increasing, with examples such as lysergic
acid and vitamin B12. Today's targets feature tens of stereogenic
centers that must be synthesized correctly with asymmetric synthesis.
Biochemistry, the chemistry of living organisms, their structure and
interactions in vitro and inside living systems, has only started in the 20th
century, opening up a new chapter of organic chemistry with enormous
scope. Biochemistry, like organic chemistry, primarily focuses on
compounds containing carbon as well.
[edit]Characterization

Since organic compounds often exist as mixtures, a variety of techniques

have also been developed to assess purity, especially important
being chromatography techniques such as HPLC and gas chromatography.
Traditional methods of separation include distillation,crystallization,
and solvent extraction.
Organic compounds were traditionally characterized by a variety of
chemical tests, called "wet methods," but such tests have been largely
displaced by spectroscopic or other computer-intensive methods of
analysis.[4] Listed in approximate order of utility, the chief analytical
methods are:
 Nuclear magnetic resonance (NMR) spectroscopy is the most commonly
used technique, often permitting complete assignment of atom
connectivity and even stereochemistry using correlation spectroscopy.
The principal constituent atoms of organic chemistry - hydrogen and
carbon - exist naturally with NMR-responsive isotopes, respectively 1H
and 13C.
 Elemental analysis: A destructive method used to determine the
elemental composition of a molecule. See also mass spectrometry,
below.
 Mass spectrometry indicates the molecular weight of a compound and,
from the fragmentation patterns, its structure. High resolution mass
spectrometry can usually identify the exact formula of a compound and
is used in lieu of elemental analysis. In former times, mass spectrometry
was restricted to neutral molecules exhibiting some volatility, but
advanced ionization techniques allow one to obtain the "mass spec" of
virtually any organic compound.
 Crystallography is an unambiguous method for determining molecular
geometry, the proviso being that single crystals of the material must be
available and the crystal must be representative of the sample. Highly
automated software allows a structure to be determined within hours of
obtaining a suitable crystal.
Traditional spectroscopic methods such as infrared spectroscopy, optical
rotation, UV/VIS spectroscopy provide relatively nonspecific structural
information but remain in use for specific classes of compounds.
Additional methods are described in the article on analytical chemistry.
[edit]Properties

Physical properties of organic compounds typically of interest include both

quantitative and qualitative features. Quantitative information include
melting point, boiling point, and index of refraction. Qualitative properties
include odor, consistency, solubility, and color.
[edit]Melting and boiling properties
In contrast to many inorganic materials, organic compounds typically melt
and many boil. In earlier times, the melting point (m.p.) and boiling point
(b.p.) provided crucial information on the purity and identity of organic
compounds. The melting and boiling points correlate with the polarity of the
molecules and their molecular weight. Some organic compounds,
especially symmetrical ones, sublime, that is they evaporate without
melting. A well known example of a sublimable organic compound is para-
dichlorobenzene, the odiferous constituent of mothballs. Organic
compounds are usually not very stable at temperatures above 300 °C,
although some exceptions exist.
[edit]Solubility
Neutral organic compounds tend to be hydrophobic, that is they are
less soluble in water than in organic solvents. Exceptions include organic
compounds that contain ionizable groups as well as low molecular
weight alcohols, amines, and carboxylic acids where hydrogen
bondingoccurs. Organic compounds tend to dissolve in organic solvents.
Solvents can be either pure substances like ether or ethyl alcohol, or
mixtures, such as the paraffinic solvents such as the various petroleum
ethers and white spirits, or the range of pure or mixed aromatic solvents
obtained from petroleum or tar fractions by physical separation or by
chemical conversion. Solubility in the different solvents depends upon the
solvent type and on the functional groups if present.
[edit]Solid state properties
Various specialized properties are of interest depending on applications,
e.g. thermo-mechanical and electro-mechanical such aspiezoelectricity,
electrical conductivity (see organic metals), and electro-optical (e.g. non-
linear optics) properties. For historical reasons, such properties are mainly
the subjects of the areas of polymer science and materials science.
[edit]Nomenclature

See also: IUPAC nomenclature

Various names and depictions for one organic compound.

The names of organic compounds are either systematic, following logically

from a set of rules, or nonsystematic, following various traditions.
Systematic nomenclature is stipulated by recommendations from IUPAC.
Systematic nomenclature starts with the name for a parent structure within
the molecule of interest. This parent name is then modified by prefixes,
suffixes, and numbers to unambiguously convey the structure. Given that
millions of organic compounds are known, rigorous use of systematic
names can be cumbersome. Thus, IUPAC recommendations are more
closely followed for simple compounds, but not complex molecules. To use
the systematic naming, one must know the structures and names of the
parent structures. Parent structures include unsubstituted hydrocarbons,
heterocycles, and monofunctionalized derivatives thereof.
Nonsystematic nomenclature is simpler and unambiguous, at least to
organic chemists. Nonsystematic names do not indicate the structure of the
compound. Nonsystematic names are common for complex molecules,
which includes most natural products. Thus, the informally named lysergic
acid diethylamide is systematically named (6aR,9R)-N,N-diethyl-7-methyl-
4,6,6a,7,8,9-hexahydroindolo-[4,3-fg] quinoline-9-carboxamide.
With the increased use of computing, other naming methods have evolved
that are intended to be interpreted by machines. Two popular formats
are SMILES and InChI.
[edit]Structural drawings
Organic molecules are described more commonly by drawings or structural
formulas, combinations of drawings and chemical symbols. Theline-angle
formula is simple and unambiguous. In this system, the endpoints and
intersections of each line represent one carbon, and hydrogen atoms can
either be notated explicitly or assumed to be present as implied by
tetravalent carbon. The depiction of organic compounds with drawings is
greatly simplified by the fact that carbon in almost all organic compounds
has four bonds, oxygen two, hydrogen one, and nitrogen three.
[edit]Classification of organic compounds
[edit]Functional groups
Main article: Functional group

The family of carboxylic acids contains a carboxyl (-COOH) functional group. Acetic acid is an
example.

The concept of functional groups is central in organic chemistry, both as a

means to classify structures and for predicting properties. A functional
group is a molecular module, and the reactivity of that functional group is
assumed, within limits, to be the same in a variety of molecules. Functional
groups can have decisive influence on the chemical and physical properties
of organic compounds. Molecules are classified on the basis of their
functional groups. Alcohols, for example, all have the subunit C-O-H. All
alcohols tend to be somewhat hydrophilic, usually form esters, and usually
can be converted to the corresponding halides. Most functional groups
feature heteroatoms (atoms other than C and H). Organic compounds are
classified according to functional groups, alcohols, carboxylic acids,
amines, etc.
[edit]Aliphatic compounds
Main article: Aliphatic compound

The aliphatic hydrocarbons are subdivided into three groups of homologous

series according to their state of saturation:
 paraffins, which are alkanes without any double or triple bonds,
 olefins or alkenes which contain one or more double bonds, i.e. di-
olefins (dienes) or poly-olefins.
 alkynes, which have one or more triple bonds.
The rest of the group is classed according to the functional groups present.
Such compounds can be "straight-chain," branched-chain or cyclic. The
degree of branching affects characteristics, such as the octane
number or cetane number in petroleum chemistry.
Both saturated (alicyclic) compounds and unsaturated compounds exist as
cyclic derivatives. The most stable rings contain five or six carbon atoms,
but large rings (macrocycles) and smaller rings are common. The smallest
cycloalkane family is the three-membered cyclopropane((CH2)3). Saturated
cyclic compounds contain single bonds only, whereas aromatic rings have
an alternating (or conjugated) double bond.Cycloalkanes do not contain
multiple bonds, whereas the cycloalkenes and the cycloalkynes do.
[edit]Aromatic compounds

Benzene is one of the best-known aromatic compounds as it is one of the simplest and most
stable aromatics.

Aromatic hydrocarbons contain conjugated double bonds. The most

important example isbenzene, the structure of which was formulated
by Kekulé who first proposed the delocalization orresonance principle for
explaining its structure. For "conventional" cyclic compounds, aromaticity is
conferred by the presence of 4n + 2 delocalized pi electrons, where n is an
integer. Particular instability (antiaromaticity) is conferred by the presence
of 4n conjugated pi electrons.
[edit]Heterocyclic compounds
Main article: Heterocyclic compound

The characteristics of the cyclic hydrocarbons are again altered if

heteroatoms are present, which can exist as either substituents attached
externally to the ring (exocyclic) or as a member of the ring itself
(endocyclic). In the case of the latter, the ring is termed
a heterocycle. Pyridine andfuran are examples of aromatic heterocycles
while piperidine and tetrahydrofuran are the corresponding alicyclic
heterocycles. The heteroatom of heterocyclic molecules is generally
oxygen, sulfur, or nitrogen, with the latter being particularly common in
biochemical systems.
Examples of groups among the heterocyclics are the aniline dyes, the great
majority of the compounds discussed in biochemistry such as alkaloids,
many compounds related to vitamins, steroids, nucleic acids (e.g. DNA,
RNA) and also numerous medicines. Heterocyclics with relatively simple
structures are pyrrole (5-membered) and indole (6-membered carbon ring).
Rings can fuse with other rings on an edge to give polycyclic compounds.
The purine nucleoside bases are notable polycyclic aromatic heterocycles.
Rings can also fuse on a "corner" such that one atom (almost always
carbon) has two bonds going to one ring and two to another. Such
compounds are termed spiro and are important in a number of natural
products.
[edit]Polymers
Main article: Polymer

This swimming board is made ofpolystyrene, an example of a polymer

One important property of carbon is that it readily forms chain or even

networks linked by carbon-carbon bonds. The linking process is
called polymerization, and the chains or networks polymers, while the
source compound is a monomer. Two main groups of polymers exist: those
artificially manufactured are referred to as industrial polymers[5] or synthetic
polymers and those naturally occurring as biopolymers.
Since the invention of the first artificial polymer, bakelite, the family has
quickly grown with the invention of others. Common synthetic organic
polymers
are polyethylene (polythene),polypropylene, nylon, teflon (PTFE), polystyre
ne, polyesters, polymethylmethacrylate (called perspex and plexiglas),
and polyvinylchloride (PVC). Both synthetic and natural rubber are
polymers.
The examples are generic terms, and many varieties of each of these may
exist, with their physical characteristics fine tuned for a specific use.
Changing the conditions of polymerisation changes the chemical
composition of the product by altering chain length, or branching, or
the tacticity. With a single monomer as a start the product is
a homopolymer. Further, secondary component(s) may be added to create
a heteropolymer (co-polymer) and the degree of clustering of the different
components can also be controlled. Physical characteristics, such as
hardness, density, mechanical or tensile strength, abrasion resistance, heat
resistance, transparency, colour, etc. will depend on the final composition.
[edit]Biomolecules

Maitotoxin, a complex organic biological toxin.

Biomolecular chemistry is a major category within organic chemistry which

is frequently studied by biochemists. Many complex multi-functional group
molecules are important in living organisms. Some are long-
chain biopolymers, and these includepeptides, DNA, RNA and
the polysaccharides such as starches in animals and celluloses in plants.
The other main classes areamino acids (monomer building blocks of
peptides and proteins),carbohydrates (which includes the polysaccharides),
the nucleic acids (which include DNA and RNA as polymers), and
the lipids. In addition, animal biochemistry contains many small molecule
intermediates which assist in energy production through the Krebs cycle,
and produces isoprene, the most common hydrocarbon in animals.
Isoprenes in animals form the important steroid structural (cholesterol) and
steroid hormone compounds; and in plants form terpenes,terpenoids,
some alkaloids, and a unique set of hydrocarbons called biopolymer
polyisoprenoids present in latex sap, which is the basis for making rubber.
Peptide Synthesis
See also peptide synthesis
Oligonucleotide Synthesis
See also Oligonucleotide synthesis
Carbohydrate Synthesis
See also Carbohydrate synthesis
[edit]Small molecules
In pharmacology, an important group of organic compounds
is small molecules, also referred to as 'small organic
compounds'. In this context, a small molecule is a small organic
compound that is biologically active, but is not a polymer. In
practice, small molecules have amolar mass less than
approximately 1000 g/mol.

Molecular models of caffeine

[edit]Fullerenes
Fullerenes and carbon nanotubes, carbon compounds with
spheroidal and tubular structures, have stimulated much
research into the related field of materials science.
[edit]Others
Organic compounds containing bonds of carbon to nitrogen,
oxygen and the halogens are not normally grouped separately.
Others are sometimes put into major groups within organic
chemistry and discussed under titles such as organosulfur
chemistry, organometallic chemistry,organophosphorus
chemistry and organosilicon chemistry.
[edit]Organic synthesis

A synthesis designed by E.J. Corey foroseltamivir (Tamiflu). This synthesis has

11 distinct reactions.

Synthetic organic chemistry is an applied science as it

borders engineering, the "design, analysis, and/or construction
of works for practical purposes". Organic synthesis of a novel
compound is a problem solving task, where a synthesis is
designed for a target molecule by selecting optimal reactions
from optimal starting materials. Complex compounds can have
tens of reaction steps that sequentially build the desired
molecule. The synthesis proceeds by utilizing the reactivity of
the functional groups in the molecule. For example,
acarbonyl compound can be used as a nucleophile by
converting it into an enolate, or as anelectrophile; the
combination of the two is called the aldol reaction. Designing
practically useful syntheses always requires conducting the
actual synthesis in the laboratory. The scientific practice of
creating novel synthetic routes for complex molecules is
called total synthesis.
There are several strategies to design a synthesis. The modern
method of retrosynthesis, developed by E.J. Corey, starts with
the target molecule and splices it to pieces according to known
reactions. The pieces, or the proposed precursors, receive the
same treatment, until available and ideally inexpensive starting
materials are reached. Then, the retrosynthesis is written in the
opposite direction to give the synthesis. A "synthetic tree" can
be constructed, because each compound and also each
precursor has multiple syntheses.
[edit]Organic reactions
Organic reactions are chemical reactions involving organic
compounds. While pure hydrocarbons undergo certain limited
classes of reactions, many more reactions which organic
compounds undergo are largely determined by functional
groups. The general theory of these reactions involves careful
analysis of such properties as the electron affinity of key
atoms, bond strengths and steric hindrance. These issues can
determine the relative stability of short-lived reactive
intermediates, which usually directly determine the path of the
reaction.
 The basic reaction types are: addition reactions, elimination
reactions, substitution reactions, pericyclic reactions,
rearrangement reactions and redox reactions. An example of a
common reaction is a substitution reaction written as:
Nu− + C-X → C-Nu + X−
where X is some functional group and Nu is a nucleophile.
The number of possible organic reactions is basically
infinite. However, certain general patterns are observed that
can be used to describe many common or useful reactions.
Each reaction has a stepwise reaction mechanism that
explains how it happens in sequence—although the
detailed description of steps is not always clear from a list of
reactants alone.
The stepwise course of any given reaction mechanism can
be represented using arrow pushing techniques in which
curved arrows are used to track the movement of electrons
as starting materials transition through intermediates to final
products.

http://www.cdli.ca/courses/chem2202/unit03_org01_ilo02/b_activity.html --sources

http://www.tutorvista.com/chemistry/uses-of-organic-compounds uses of org

comp

http://www.askiitians.com/forums/Organic-Chemistry/21/667/Importance-of-Organic-
Compounds.htm importance

http://en.wikipedia.org/wiki/Organic_compound org. comp