Organic chemistry is a chemistry subdiscipline involving the
scientific study of the structure, properties, and reactions of organic
compounds and organic materials, i.e., matter in its various forms that contain
carbon atoms. Study of structure includes using spectroscopy and other physical
and chemical methods to determine the chemical composition and constitution of
organic compounds and materials. Study of properties includes both physical
properties and chemical properties, and uses similar methods as well as methods
to evaluate chemical reactivity, with the aim to understand the behavior of the
organic matter in its pure form (when possible), but also in solutions,
mixtures, and fabricated forms. The study of organic reactions includes both their
preparation : by synthesis or by other means ,as well as their subsequent
reactivities, both in the laboratory and via theoretical (in silico) study.
The objects of study in organic chemistry include
hydrocarbons, compounds containing only carbon and hydrogen, as well as
compositions based on carbon but containing other elements. Organic chemistry
overlaps with many areas including medicinal chemistry, biochemistry,
organometallic chemistry, and polymer chemistry, as well as many aspects of
materials science.
Organic compounds form the basis of all earthly life. They
are structurally diverse. The range of application of organic compounds is
enormous. They either form the basis of, or are important constituents of, many
products including plastics, drugs, petrochemicals, food, explosive material,
and paints.
Polymers are very large molecules
made of repeating patterns of small molecules, called monomers.Many polymers are made by repeating the same
small molecule over and over again.Others are made from two monomers linked in a pattern.While most polymers with which you are
familiar are man-made, there are some biological polymers ; proteins, nucleic
acids, and complex carbohydrates – that are fundamental to the way your body
functions.These can be made from one
monomer all the way to twenty different small molecules coming together to form
one large polymer. Synthetic polymers are from the chemistry industry.
Because they contain carbon,
polymers are categorized as organic compounds.The most common element found in polymers, besides carbon, is
hydrogen.Many polymers are manufactured
from feedstock, or starting materials, obtained from petroleum.Petroleum is a mixture of hydrocarbon compounds
pumped from underground and is the result of extreme time and pressure acting
on ancient sea plants and animals.However, the compounds used to make polymers are not necessarily
obtained directly from petroleum deposits.Petroleum must first be refined before it can be made into polymers. All
polymers must then be manufactured through polymerization reactions.The two most common reaction types used to
make polymers are addition reactions and condensation reactions.
In most addition polymerization
reactions, hydrocarbons with double bonds, called alkenes, react with each
other, breaking the double bond within the small molecules and forming a new
covalent bond between the two monomers.Ethylene, C2H4, is commonly used and is combined to make polyethylene.
Varying reaction conditions and
the type of catalyst used will result in different structures of polyethylene
polymers.One method uses high
temperature and pressure with a peroxide catalyst and results in low-density
polyethylene, LDPE.Another method,
called Ziegler-Natta polymerization, takes place at lower temperature and
pressure and produces high-density polyethylene, or HDPE. LDPE and HDPE are
both made from the same monomer, ethylene, yet have very different physical
properties. The differences in their properties is a direct consequence of the
degree of crystallization found among the polymer molecules.Molecules that are highly branched, such as
LDPE, cannot “line up” with each other.The result is an amorphous solid – one that does not have a repeating,
predictable structure.As the molecule
becomes less and less branched, and more and more long-chain-like, the
intermolecular attraction between them becomes stronger, and the structure
takes on more of a crystalline appearance.Crystalline solids have a regular, repeating arrangement. LDPE has many
branches, and is less chain-like in structure.It is softer, more flexible, and more easily deformed than HDPE. HDPE
molecules are much longer, less branched, packed more closely together, and
have stronger intermolecular attraction than LDPE.The variations in their properties lend them
to different, albeit equally useful, applications.
Condensation reactions occur
between molecules that contain oxygen along with hydrogen and carbon.Two hydrogen-containing functional groups
must be present on each molecule for the reaction to proceed.
Note that in the polymerization of Nylon 6,6,
a hydroxyl group (-OH group) is removed from one molecule and a hydrogen atom
is removed from the other.The two
molecules may be joined to form a dimer, and those dimers combined to form a
polymer, or the polymer may be built monomer by monomer.Either way, a water molecule is formed as a
byproduct.
Besides nylon, some common
polymers formed via condensation include:polyester, a textile fiber; polycarbonate, a lightweight material used
in eyeglasses, molded sign faces, and NASCAR seats; Teflon, a non-stick coating
on cookware; Kevlar, the material used in bullet-proof vests; and, polyurethane,
used in many foam applications.
Some of the Industrial Uses :
Plastics
Plastics are polymers made from
petrochemicals. When plastics are used for packaging rather than steel,
aluminum, glass, paper, or wood, the net emissions saved are 222 MtCO2e.
Polymers can also be used to replace glass in agricultural green houses, in
window frames instead of wood and aluminum frames, and in carpeting. All of
these uses of plastics can reduce greenhouse gas emissions.
Automotive Industry
The automotive industry uses
polymers, such as carbon fiber reinforced polymers, in the design and
manufacturing of vehicles. Polymers have a wide range of uses in automobile
manufacturing. They are used in the chassis, under-the-hood, in the body, and
in the interior. Using polymer based materials reduces the weight of the
vehicle, which reduces fuel consumption, which reduces GHG emissions. The
McKinsey Report estimates that the use of plastics in the automotive industry
saves about 120 MtCO2e from entering the atmosphere.
Plastics in Piping
Most people are familiar with PVC
and HDPE piping. The plastics used in these pipes are polymers created by the
chemistry industry. When compared to different metal pipe options, the lifetime
of plastic pipes are similar. Savings in GHG emissions come from lower raw
material use, and differences in production, and disposal footprints. Overall,
plastics in piping has a net emissions savings of 65.4 MtCO2e.
Electronics
The chemistry industry is working
on new uses for polymers as well. In development are conductive polymers for
printable electronics. Polymer Electrolyte Membrane, PEM, (or Proton Exchange
Membrane) fuel cells are already in use in hydrogen fuel cell vehicles. The
industry is also working on materials for advanced fuel cells including a
polymer electrolyte fuel cell (PEFC).
Perfume has been used throughout history for a variety of
reasons. People have used perfume, oils and unguents on their bodies for
thousands of years in lesser or greater amounts dependant on fashion whims. In
the early Egyptians used perfumed balms as part of religious ceremonies and
later as part of pre love making preparations. Now it is used by thousands of
Consumers to indicate their lifestyle, character, presence and Specialty in the
industry. This explains how the perfumes are made and what ingredients are
involved in it.
Perfume is made from about 78% to 95% of specially denatured
ethyl alcohol and a remainder of essential oils. Perfumes are made up of a
blend of different aromas that usually come from essential oils. Perfume
formulations can be expressed in volumetric or weight proportions of each of
its components. Perfumes today are being made and used in different ways than
in previous centuries. Perfumes are being manufactured more and more frequently
with synthetic chemicals rather than natural oils.
Natural ingredients—flowers, grasses, spices, fruit, wood,
roots, resins, balsams, leaves, gums, and animal secretions—as well as
resources like alcohol, petrochemicals, coal, and coal tars are used in the
manufacture of perfumes. Some plants, such as lily of the valley, do not
produce oils naturally. In fact, only about 2,000 of the 250,000 known
flowering plant species contain these essential oils. Therefore, synthetic
chemicals must be used to re-create the smells of non-oily substances. Synthetics
also create original scents not found in nature.
Some perfume ingredients are animal products. For example,
castor comes from beavers, musk from male deer, and ambergris from the sperm
whale. Animal substances are often used as fixatives that enable perfume to
evaporate slowly and emit odors longer. Other fixatives include coal tar,
mosses, resins, or synthetic chemicals. Alcohol and sometimes water are used to
dilute ingredients in perfumes. It is the ratio of alcohol to scent that
determines whether the perfume is "eau de toilette" (toilet water) or
cologne.
Types of Aromatic
Compounds
A common source of
aromatic compounds comes from plants. These compounds are usually the
byproducts of chemicals made to discourage animals from eating the plants.
These compounds can be found in the bark (such as cinnamon), the flowers (such
as rose and jasmine scents), fruits (such as apples and strawberries), leaves
and other plant parts. Perfumes can also be found in ambergris, which is an
oxidized fatty substance commonly found in whales. Other animal sources include
musk, which can be taken from the musk sacks of deer.
Aromatic Compound
Extraction
The most common
method of obtaining aromatic compounds for the purpose of turning them into
perfume is the solvent extraction process. In this method, the source material
is put into a liquid that can dissolve the desired material. These liquids can
be made up of hexane and ether. Another technique is distillation, in which
steam from boiling water is passed through the desired material. The condensed
steam is then concentrated and purified in a special flask. Other methods
include crushing plants between presses and embedding them into wax.
Perfume making
process :
Collection
Collection of raw materials is the first step in the perfume
making process. Fragrance can be obtained from flowers, grasses, mosses,
leaves, tree barks and fruit peels. Once raw materials are collected, the
fragrance is extracted by distillation, absorption or extraction using
solvents.
Distillation
In the distillation method, raw materials are steamed. As
the steam rises, the scent is carried into a glass tube where the mixture
condenses as it cools. The mixture is then put into flask where the essential
oil naturally rises to the top and is skimmed off for use in the perfume.
Absorption
Absorption is used for raw materials that can't with stand
the heat of the distillation process. They are steeped in heated fats or oils,
then filtered through fabric to obtain the scented solid. The solid is then
washed in alcohol. When the fat is removed, the perfumed alcohol remains.
Extraction
Fragrance also is drawn when plant matter and volatile
solvents are combined in a rotating tank. The solvent extracts the essential
oils and dissolves the plant matter, leaving a wax-like oil. Once the oil has
evaporated, a perfume paste remains.
Aromas
Musk and castor are animal secretions frequently used in
perfume making. Synthetically produced aromas also are used.
Blending
Once the perfume oil is extracted, the blending process
commences. A perfumer, known as "a nose," uses an extensive knowledge
of fragrance characteristic to blend anywhere from 20 to 800 raw materials to
compose a scent. Once the scent is developed and tested, batches are
robotically mixed.
The pure perfume oil is then diluted with alcohol and water.
If a full perfume is desired, 10 to 20 percent of the oil is dissolved in
alcohol with a minute amount of water. Cologne is 3 to 5 percent oil, 80 to 90
percent alcohol and 10 percent water. An eau de toilette is 2 percent oil, 60
to 80 percent alcohol and 20 percent water. Then the perfume is ready to be
aged, filtered and bottled.
Fertilizer is a substance added to soil to improve plants'
growth and yield. First used by ancient farmers, fertilizer technology
developed significantly as the chemical needs of growing plants were
discovered. Modern synthetic fertilizers are composed mainly of nitrogen,
phosphorous, and potassium compounds with secondary nutrients added. The use of
synthetic fertilizers has significantly improved the quality and quantity of
the food available today, although their long-term use is debated by
environmentalists. Like all living organisms, plants are made up of cells.
Within these cells occur numerous metabolic chemical reactions that are
responsible for growth and reproduction. Since plants do not eat food like
animals, they depend on nutrients in the soil to provide the basic chemicals
for these metabolic reactions. The supply of these components in soil is
limited, however, and as plants are harvested, it dwindles, causing a reduction
in the quality and yield of plants.
Fertilizers replace the chemical components that are taken
from the soil by growing plants. However, they are also designed to improve the
growing potential of soil, and fertilizers can create a better growing
environment than natural soil. They can also be tailored to suit the type of crop
that is being grown. Typically, fertilizers are composed of nitrogen,
phosphorus, and potassium compounds. They also contain trace elements that
improve the growth of plants. The primary components in fertilizers are
nutrients which are vital for plant growth. Plants use nitrogen in the
synthesis of proteins, nucleic acids, and hormones. When plants are nitrogen
deficient, they are marked by reduced growth and yellowing of leaves. Plants
also need phosphorus, a component of nucleic acids, phospholipids, and several
proteins. It is also necessary to provide the energy to drive metabolic
chemical reactions. Without enough phosphorus, plant growth is reduced.
Potassium is another major substance that plants get from the soil. It is used
in protein synthesis and other key plant processes. Yellowing, spots of dead
tissue, and weak stems and roots are all indicative of plants that lack enough
potassium.
Calcium, magnesium, and sulfur are also important materials
in plant growth. They are only included in fertilizers in small amounts,
however, since most soils naturally contain enough of these components. Other
materials are needed in relatively small amounts for plant growth. These
micronutrients include iron, chlorine, copper, manganese, zinc, molybdenum, and
boron, which primarily function as cofactors in enzymatic reactions. While they
may be present in small amounts, these compounds are no less important to
growth, and without them plants can die. Many different substances are used to
provide the essential nutrients needed for an effective fertilizer. These
compounds can be mined or isolated from naturally occurring sources. Examples
include sodium nitrate, seaweed, bones, guano, potash, and phosphate rock.
Compounds can also be chemically synthesized from basic raw materials. These
would include such things as ammonia, urea, nitric acid, and ammonium
phosphate. Since these compounds exist in a number of physical states,
fertilizers can be sold as solids, liquids, or slurries.
History
The process of adding substances to soil to improve its
growing capacity was developed in the early days of agriculture. Ancient
farmers knew that the first yields on a plot of land were much better than
those of subsequent years. This caused them to move to new, uncultivated areas,
which again showed the same pattern of reduced yields over time. Eventually it
was discovered that plant growth on a plot of land could be improved by
spreading animal manure throughout the soil. Over time, fertilizer technology
became more refined. New substances that improved the growth of plants were discovered.
The Egyptians are known to have added ashes from burned weeds to soil. Ancient
Greek and Roman writings indicate that various animal excrements were used,
depending on the type of soil or plant grown. It was also known by this time
that growing leguminous plants on plots prior to growing wheat was beneficial.
Other types of materials added include sea-shells, clay, vegetable waste, waste
from different manufacturing processes, and other assorted trash.
Organized research into fertilizer technology began in the
early seventeenth century. Early scientists such as Francis Bacon and Johann
Glauber describe the beneficial effects of the addition of saltpeter to soil.
Glauber developed the first complete mineral fertilizer, which was a mixture of
saltpeter, lime, phosphoric acid, nitrogen, and potash. As scientific chemical
theories developed, the chemical needs of plants were discovered, which led to
improved fertilizer compositions. Organic chemist Justus von Liebig
demonstrated that plants need mineral elements such as nitrogen and phosphorous
in order to grow. The chemical fertilizer industry could be said to have its
beginnings with a patent issued to Sir John Lawes, which outlined a method for
producing a form of phosphate that was an effective fertilizer.
Raw
Materials
The fertilizers outlined here are compound fertilizers
composed of primary fertilizers and secondary nutrients. These represent only
one type of fertilizer, and other single nutrient types are also made. The raw
materials, in solid form, can be supplied to fertilizer manufacturers in bulk
quantities of thousands of tons, drum quantities, or in metal drums and bag
containers. Primary fertilizers include substances derived from nitrogen,
phosphorus, and potassium. Various raw materials are used to produce these compounds.
When ammonia is used as the nitrogen source in a fertilizer, one method of
synthetic production requires the use of natural gas and air. The phosphorus
component is made using sulfur, coal, and phosphate rock. The potassium source
comes from potassium chloride, a primary component of potash. Secondary
nutrients are added to some fertilizers to help make them more effective.
Calcium is obtained from limestone, which contains calcium carbonate, calcium
sulphate, and calcium magnesium carbonate. The magnesium source in fertilizers
is derived from dolomite. Sulfur is another material that is mined and added to
fertilizers. Other mined materials include iron from ferrous sulfate, copper,
and molybdenum from molybdenum oxide.
The
Manufacturing Process
Fully integrated factories have been designed to produce
compound fertilizers. Depending on the actual composition of the end product,
the production process will differ from manufacturer to manufacturer.
Nitrogen fertilizer
component
• Ammonia is one nitrogen fertilizer component that can be
synthesized from in-expensive raw materials. Since nitrogen makes up a
significant portion of the earth's atmosphere, a process was developed to
produce ammonia from air. In this process, •natural gas and steam are pumped
into a large vessel. Next, air is pumped into the system, and oxygen is removed
by the burning of natural gas and steam. This leaves primarily nitrogen,
hydrogen, and carbon dioxide. The carbon dioxide is removed and ammonia is
produced by introducing an electric current into the system. Catalysts such as
magnetite (Fe 3 O 4 ) have been used to improve the speed and efficiency of
ammonia synthesis. Any impurities are removed from the ammonia, and it is
stored in tanks until it is further processed.
• While ammonia itself is sometimes used as a fertilizer, it
is often converted to other substances for ease of handling. Nitric acid is
produced by first mixing ammonia and air in a tank. In the presence of a
catalyst, a reaction occurs which converts the ammonia to nitric oxide. The
nitric oxide is further reacted in the presence of water to produce nitric
acid.
•Nitric acid and ammonia are used to make ammonium nitrate.
This material is a good fertilizer component because it has a high concentration
of nitrogen. The two materials are mixed together in a tank and a
neutralization reaction occurs, producing ammonium nitrate. This material can
then be stored until it is ready to be granulated and blended with the other
fertilizer components.
Phosphorous
fertilizer component
To isolate phosphorus
from phosphate rock, it is treated with sulfuric acid, producing phosphoric
acid. Some of this material is reacted further with sulfuric acid and nitric
acid to produce a triple superphosphate, an excellent source of phosphorous in
solid form.
•Some of the phosphoric acid is also reacted with ammonia in
a separate tank. This reaction results in ammonium phosphate, another good
primary fertilizer.
Potassium fertilizer
component
• Potassium chloride is typically supplied to fertilizer
manufacturers in bulk. The manufacturer converts it into a more usable form by
granulating it. This makes it easier to mix with other fertilizer components in
the next step.
Granulating and
blending
• To produce fertilizer in the most usable form, each of the
different compounds, ammonium nitrate, potassium chloride, ammonium phosphate,
and triple superphosphate are granulated and blended together. One method of
granulation involves putting the solid materials into a rotating drum which has
an inclined axis. As the drum rotates, pieces of the solid fertilizer take on
small spherical shapes. They are passed through a screen that separates out adequately
sized particles. A coating of inert dust is then applied to the particles,
keeping each one discrete and inhibiting moisture retention. Finally, the
particles are dried, completing the granulation process.
•The different types of particles are blended together in
appropriate proportions to produce a composite fertilizer. The blending is done
in a large mixing drum that rotates a specific number of turns to produce the
best mixture possible. After mixing, the fertilizer is emptied onto a conveyor
belt, which transports it to the bagging machine.
Bagging
• Fertilizers are typically supplied to farmers in large
bags. To fill these bags the fertilizer is first delivered into a large hopper.
An appropriate amount is released from the hopper into a bag that is held open
by a clamping device. The bag is on a vibrating surface, which allows better
packing. When filling is complete, the bag is transported upright to a machine
that seals it closed. The bag is then conveyored to a palletizer, which stacks
multiple bags, readying them for shipment to distributors and eventually to
farmers.
