Industrial Chemistry
XII – Chemistry SLO 22
22.1 Introduction
22.1.1 discuss the importance of chemical industries for the economy of Pakistan;
22.1.2 list the raw materials available in Pakistan for various chemical and petrochemical
industries;
Industrial Chemistry
The branch of chemistry which applies physical and chemical procedures towards
the transformation of natural raw materials and their derivatives to products that
are of benefit to humanity.
22.1.1 discuss the importance of chemical industries for the economy of Pakistan;
22.1.2 list the raw materials available in Pakistan for various chemical and petrochemical
industries;
RAW MATERIAL FOR THE CHEMICAL INDUSTRY
Raw materials from the atmosphere
It is the source of air from which six industrial gases namely N2, O2, Ne,
Ar, Kr and Xe are manufactured. Mass of earth’s atmosphere is
approximately 5×1015 tons and therefore the supply of the gases is
virtually unlimited.
22.1.1 discuss the importance of chemical industries for the economy of Pakistan;
22.1.2 list the raw materials available in Pakistan for various chemical and petrochemical
industries;
RAW MATERIALS FROM THE HYDROSPHERE
Seawater is a good source of sodium chloride, magnesium and
bromine. Ocean water which amounts to about 1.5×1021 liter contains
3.5 percent by mass dissolved material.
RAW MATERIALS FROM LITHOSPHERE
Coal, natural gas and crude petroleum besides being energy sources
are also converted to thousands of chemicals.
22.1.1 discuss the importance of chemical industries for the economy of Pakistan;
22.1.2 list the raw materials available in Pakistan for various chemical and petrochemical
industries;
RAW MATERIALS FROM THE BIOSPHERE
Vegetation and animals contribute raw materials to the so-called agrobased industries. Oils, fats, waxes, resins, sugar, natural fibers and
leather are examples of thousands of natural products.
22.2 Safety Measurement
22.2.1 List safety precautions that should be followed in chemical industries;
More than two thousand deaths from a methyl isocyanate chemical leak in Bhopal, India, drew
world attention to serious hazards in the chemical industry.
Disaster Prevention
• A management subsystem which includes management personnel, process specifications, plant
design, standard operating procedures, and the written emergency plan.
• A personnel subsystem which assigns and defines roles, for both normal and emergency
operations, and provides appropriate training. This may also include labor/management safety
committees.
• A physical subsystem which may include transportation systems for materials, ventilation systems,
waste removal systems, containment systems, refrigeration systems, storage areas,
communications systems, and other process related equipment.
• An emergency services subsystem including plant and community components.
22.2 Safety Measurement
22.2.1 List safety precautions that should be followed in chemical industries;
Plant Management
• Who is in charge? What are the lines of authority under normal
operating conditions? in transition times, like during startup and
shutdown procedures? In emergencies?
• Can information be transmitted quickly and easily from: worker to
supervisor? supervisor to worker?
22.2 Safety Measurement
22.2.1 List safety precautions that should be followed in chemical industries;
Plant Layout
Plant layout has some specific safety aspects.
• Separation and isolation
• Chemicals which may react with one another are to be physically separated, oxidizers are to be stored in areas remote from
fuel storage.
• Areas of potential explosions storage of explosives, reaction vessels) are to be isolated so if there is an explosion, the
damage and risk to employees is minimized.
• Drainage
• Where hazardous liquids may leak or spill from piping or vessels, what provisions are made to prevent their spread to areas
where employees may be exposed to the hazard? Examples of possible methods include diking and grading.
• Has the company made any provisions to control unexpected hazardous vapor or gas releases within the drain lines?
22.2 Safety Measurement
22.2.1 List safety precautions that should be followed in chemical industries;
• Housekeeping
• Are work areas well maintained?
• Enclosed spaces
• Some processes which are safe in open air may become hazardous if
enclosed. If areas of potential or frequent leaks or spills are enclosed to
prevent environmental contamination or the spread of the chemicals, are
there adequate precautions to protect employees? Examples include
ventilating the room and treating the exhaust; automatically sampling the air
in the room or vault; having employees sample before entering the room.
22.2 Safety Measurement
22.2.1 List safety precautions that should be followed in chemical industries;
Contamination Control
Potentially reactive chemicals may have their reactions catalyzed by
common materials which easily enter systems whenever seals are
opened. Examples include water or rust which may easily enter a
system during transfer from one vessel to another, either during
hookup or disconnect, or during pressurizing or venting of tanks.
22.2 Safety Measurement
22.2.1 List safety precautions that should be followed in chemical industries;
• If such potential catalysts are identified, how are they excluded from the system?
Examples include:
• If vessels are pressurized by inert gases, are there filters in the gas lines to remove solid particles?
• If vacuum relief or pressure relief valves are on the vessels, how are they protected so potentiality
hazardous contaminant can enter through them when open?
• When systems are opened for maintenance purposes, what precautions are taken to
prevent contamination? What is done to safeguard the system while it is open? What
precautions are taken to ensure that replacement parts are free of contaminants
incompatible and/or incompatiable materials? When connections are made and broken
(e.g., during transfer from rail cars or trucks), what measures are taken to ensure
contaminants do not enter the system?
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
Dyes and Pigments
A dye is a coloured compound, normally used in solution, which is capable of being
fixed to a fabric.
The dye must be or chemically stable so that the color will not wash with soap and
water, or fade on exposure to sunlight (UV light).
Dye Color – Chromophore
Dye Fixing property – Acidic/Basic auxochromic groups such as OH, SO3H, NH2,
NR2.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
Classification of dyes by structure
Classification of dyes by methods of application
Classification of dyes by structure
Dyes may be classified according to the type of chromophores present in their
structures. This method of classification includes the following main types:
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
1. Nitro and Nitroso Dyes
2. Azo Dyes
3. Triarylmethane Dyes
1. Nitro and Nitroso Dyes
The NO2 and NO groups are chromophores in this class of dyes.
These dyes have one or more nitro or nitroso group conjugated with an electron
donating group via an aromatic system.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
Naphthol Yellow S
Mordant Green 4
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
Checkpoint:
Write down the chromophores and auxochromes from the above dyes.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
2. Azo Dyes
Azo dyes are the most widely used dyes and represent over 60 % of the total dyes.
Azo dyes contain at least one nitrogen-nitrogen (N=N) double bond, however many
different structures are possible.
The Azo group is attached to two groups of which at least one but, more usually,
both are aromatic.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
Checkpoint: What is the difference between a chromophore and auxochrome?
Answer: Chromophore gives color to the dye while auxochrome gives fixing
property.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
(a) Para Red (Azo dye)
First azo dye to be prepared. Obtained by the reaction of diazotized p-nitroaniline
with β-naphthol on fabric itself.
Para Red
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
(b) Methyl Orange (Azo dye)
Methyl orange imparts orange color to wool and silk but the color is not resistant to
sunlight or washing.
It is a valuable indicator for acid-base titrations because it gives yellow color in
basic solution and red color in acid solution.
The change in color is due to the change in the structure of the ions.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
Disperse Yellow
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
(c) Congo Red (Azo dye)
Congo red contains two azo groups. It is obtained by coupling tetrazotised
benzidine with two molecules of naphthionic acid.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
(d) Bismarck Brown (Azo dye)
It is obtained by coupling tetrazotised m-diaminobenzene with two molecules of mdiaminobenzene.
Bismarck brown is a brown dye used in boot polishes and for dyeing wool and
cotton.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
3. Triarylmethane Dyes
In Triarylmethane dyes, a central carbon is bonded to three aromatic rings one of
which is in the quinoid form (the chromophore). The auxochromes are –NH2, -NR2
and –OH. Examples are
(a) Malachite Green (Triarylmethane dye)
Malachite green has a deep green-blue color. Although the color fades in light,
malachite green is used as a direct dye for wool and silk.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
(b) Phenolphthalein (Triarylmethane dye)
It is also a Triarylmethane dye but it is better known as an acid-base indicator.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
4. Anthraquinone Dyes
The para quinoid chromophore is present in these anthracene-type dyes. Alizarin is
a typical Anthraquinone dye.
Alizarin
Alizarin forms ruby red crystals which dissolve in alkali to give purple solutions. It is
used to dye wool and cotton.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
5. Indigo Dyes
Indigo is an example of the type of dyes which contain carbonyl chromophore.
It is a dark-blue crystalline compound, insoluble in water. It is used for dyeing
cotton by the Vat Process.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
Classification of dyes by methods of application
1. Direct Dyes
These can be applied to a fabric by direct immersion in a water solution of the dye.
A direct dye contains acidic or basic auxochrome which combines with the opposite
polar group present in the chemical structure of the fiber.
Wool and silk are readily dyed by this method.
Martius Yellow, a typical direct dye, has the acidic auxochrome –OH which interacts
with the basic –NH2 group of wool or silk.
Fiber – NH + HO – Dye -> Fiber – NH3 + -----O – Dye
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
2. Vat Dyes
These dyes are insoluble in water but on reduction with sodium hydrosulphide in a
vat form colorless soluble compound which has a great affinity for cotton and other
cellulose fibers.
The cloth is soaked in the solution of a reduced dye and then hung in air, or treated
with oxidants.
As a result, the colorless compound is oxidized back to the insoluble dye which is
now bound to the fabric. Indigo is a good example of a vat dye.
Indigo
Leucoindigo
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
3. Mordant Dyes
This class of dyes has no natural affinity for the fabric and are applied to it with the
help of salts e.g., oxides of aluminum or chromium.
These salts are called Mordants. A fiber such as cotton is first treated with a
mordant and then with the dye solution.
The mordant forms an insoluble coordination complex between the fiber and the
dye and bind the two.
The insoluble complex compound appears in the form of lakes that are fast to light
and washing.
The mordant dyeing is the most suitable for wool and nylon. Alizarin is an example
of a mordant dye.
22.3 Dyes and Pigments
22.3.1 Types of dyes;
22.3.2 Importance of dyes and pigments in cosmetic, textile, paints and food industry;
4. Azoic Dyes (Ingrain Dyes)
In this method of dyeing, the water insoluble azo dye is produced in the fabric
itself. The cloth is first soaked in the solution of a coupling reagent usually a phenol
or naphthol. Then it is immersed in the solution of an auxochromes. The azoic
dyeing particularly suitable for cotton and other cellulosic fiber but may also be
used for nylon.
5. Disperse Dyes
These dyes are insoluble in water but can be dispersed in a colloidal form in water.
The fabric is immersed in the colloidal dispersion of the dye. The fine dye particles
are absorbed into the crystal structure of the fabric. Disperse dyes are used with
modern synthetic fabrics such as nylon, orlon, polyester and cellulose acetate.
22.4 Petro-chemicals
22.4.1 The process of: a. fractional distillation b. refining of petroleum;
Petrochemicals are chemical products derived from petroleum. Some chemical
compounds made from petroleum are also obtained from other fossil fuels such as coal or
natural gas, or renewable sources such as corn or sugar cane.
Types/Classes of petrochemicals
a. Olefins including ethylene and propylene,
b. Aromatics
c. Synthesis Gas
Assignment: Search for the products of each class mentioned above and write in your note
book
22.4.1 The process of: a. fractional distillation b. refining of petroleum;
Fractional distillation is the separation of a mixture into its component parts, or
fractions.
Chemical compounds are separated by heating them to a temperature at which
one or more fractions of the mixture will vaporize.
It uses distillation to fractionate. Generally the component parts have boiling points
that differ by less than 25 °C (45 °F) from each other under a pressure of one
atmosphere.
If the difference in boiling points is greater than 25 °C, a simple distillation is
typically used.
22.4.1 The process of: a. fractional distillation b. refining of petroleum;
The main difference between fractional distillation and simple distillation is that
simple distillation separate liquids with boiling point gaps of at least 50 degrees
whereas fractional distillation separates liquids with closer boiling points.
22.4.1 The process of: a. fractional distillation b. refining of petroleum;