Xavier University – Ateneo de Cagayan Corrales Avenue, Cagayan de Oro City Cyclic Intermediates and Dyes Submitted to: Engr. Edwin Richard R. Ortiz ChE 511 Instructor Submitted by: Ilea A. Verano BS ChE 5 August 16, 2010
Xavier University – Ateneo de Cagayan Corrales Avenue, Cagayan de Oro City
Cyclic Intermediates and Dyes
Submitted to: Engr. Edwin Richard R. Ortiz
ChE 511 Instructor
Submitted by: Ilea A. Verano
BS ChE 5
August 16, 2010
REPORT OUTLINE: Cyclic Intermediates and Dyes
I. Dye Intermediates
II. Intermediate Classification
a. Inorganic Materials
b. Primary Intermediates
c. Dye Intermediates
III. Introduction to Dyes
IV. Classification System for Dyes
a. Classification by Chemical Class
b. Classification by Usage or Application
V. Nomenclature of Dyes
a. Commercial Trade Name
b. Colour Index
VI. Equipment and Manufacture
a. Reaction
b. Product Isolation
c. Product drying, grinding, and/or finishing
d. Waste Characteristics
I. DYE INTERMEDIATES
The precursors of dyes are called dye intermediates. They are obtained from
simple raw materials, such as benzene and naphthalene, by a variety of chemical
reactions. Usually, the raw materials are cyclic aromatic compounds, but acyclic
precursors are used to synthesize heterocyclic intermediates. The intermediates
are derived from two principal sources, coal tar and petroleum.
II. SOURCES OF RAW MATERIALS
Coal tar results from the pyrolysis of coal and is obtained chiefly as a by-product in
the manufacture of coke for the steel industry. Products recovered from the
fractional distillation of coal tar have been the traditional organic raw material for
the dye industry. Among the most important are benzene, toluene, xylene
naphthalene, anthracene, acenaphthene, pyrene, pyridine, carbazole, phenol, and
cresol.
The petroleum industry is now the principal supplier of benzene, toluene, the
xylenes, and naphthalene. Petroleum displaced coal tar as the primary source for
these aromatic compounds after World War II because it was relatively cheap and
abundantly available. However, the re-emergence of king coal is predicted for the
twenty-first century, when oil supplies are expected to dwindle and the cost of
producing chemicals from coal (including new processes based on synthesis gas)
will gradually become more competitive.
III. INTERMEDIATES CLASSIFICATION
Intermediates may be conveniently divided into primary intermediates (primaries)
and dye intermediates. Large amounts of inorganic materials are consumed in both
intermediates and dyes manufacture.
a. Inorganic Materials
These include acids (sulfuric, nitric, hydrochloric, and phosphoric), bases (caustic
soda, caustic potash, soda ash, sodium carbonate, ammonia, and lime), salts
(sodium chloride, sodium nitrite, and sodium sulfide) and other substances such as
chlorine, bromine, phosphorus chlorides, and sulfur chlorides. The important point
is that there is a significant usage of at least one inorganic material in all
processes, and the overall tonnage used by, and therefore the cost to, the dye
industry is high.
b. Primary Intermediates
Primary intermediates are characterized by one or more of the following
descriptions, which associate them with raw materials rather than with
intermediates.
1. Manufactured in a dedicated plant, i.e., one devoted to a single product or at
most two or three closely related products.
2. At least 1000 t/yr capacity from a single plant and may be up to 100,000 t/yr, e.g.,
aniline.
3. Manufacturing process and/or operation is continuous or semicontinuous, i.e., at
least one stage is in a continuous, as distinct from batch, mode.
4. A primary intermediate has established usage in basic industries such as rubber,
polymers, or agrochemicals in addition to dyes.
c. Dye Intermediates
Dye intermediates are defined as those precursors to colorants that are
manufactured within the dyes industry, and they are nearly always colorless.
Colored precursors are conveniently termed color bases. As distinct from primaries
they are only rarely manufactured in single-product units because of the
comparatively low tonnages required. Fluorescent brightening agents (FBAs) are
neither intermediates nor true colorants.
Intermediates vary in complexity, usually related to the number of chemical and
operational stages in their manufacture, and therefore cost. Prices may be classed
as cheap (less than $1500/t, as with primaries), average ($1500 to $5000/t) or
expensive (more than $5000/t).
IV. INTRODUCTION TO DYES
Frequently the color of a product is the reason for its sale. For this reason, it is
dyes are important for manufacturers to control and manipulate the color or hue of
their final product. Dyes add value to products far beyond their cost.
Dyes are colored, ionizing and aromatic organic compounds which show an affinity
towards the substrate (textile, leather, etc.) to which it is being applied.
The preparation and application of dyestuffs is one of the oldest forms of human
activities. Evidences of which were found by excavation at archeological sites
where ancient fabrics were unearthed. There is also mention of it in the Bible and
other works of classical antiquity. It was in 2600 BC when earliest written records
of the use of dyestuffs were found in China.
Perhaps one of the real breakthroughs in the history of dyes came in 1856 when a
teenager who was experimenting at his makeshift laboratory in home made a
certain discovery that acted as a sort of launching pad for the modern chemicals
industry.
William Perkin an 18-year-old student was working on chemical synthesis of
natural products. William Perkin chanced upon his now famous 'Aniline Mauve' dye
while he was attempting to synthesize quinine, the only cure for malaria. Perkin
named his color Mauveine, after the French name of non-fast color which was
made of natural dyes. So "Mauve" (a basic dye) was the first synthetic dye stuff.
Mauve was a derivative of coal tar. It was the first mass-produced dye, that was
commercially available and the idea was born that a color could be made in the
factory.
For dyes to be effective, they must be colored and must impart its color to
something else (formally called a substrate) on a reasonably permanent basis. A
dye consists of a color-producing structure, the chromogen (electron acceptor) and
a part to regulate the solubility and dyeing properties, the auxochrome (electron
donor). The chromogen is an aromatic body containing a color-giving group
commonly called the chromophore. Chromophore groups cause color by altering
absorption bands in the visible spectrum.
Some of the common chromophores are:
1. The nitroso group
2. The nitro group
3. The azo group
4. The ethylene group
5. The carbonyl group
6. The carbon-nitrogen groups
7. The carbon-sulfur groups
These groups add color to aromatic bodies by causing displacement of, or an
appearance of, absorbent bands in the visible spectrum. The chromophore groups
are the basis of one method of classifying dyes.
Some molecules lose their colors when the chromophore groups are saturated.
The auxochromes, the part of the dye which causes it to adhere to the material
which it colors usually are: -NH2, -OH, -NR2, -COOH and SO3H. These
auxochromes are salt-forming which aids the solubility of the dye in acidic and
basic medium. Auxochromes also aid to intensify the color of dyes.
V. CLASSIFICATION SYSTEM FOR DYES
Dyes may be classified according to a dual system devised by the Society of
Dryers and Colourists and the American Association of Textile Chemists and
Colorists. Published as the Colour Index, dyes may be classified according to (1)
its chemical class, expressed an assigned number and (2) its usage or application,
expressed through its generic name.
a. Classification by Chemical Class
According to Hunger (2003), the most appropriate system for the classification of
dyes is by chemical structure.
The advantages of classifying dyes by chemical structure are as follows:
1. It readily identifies dyes as belonging to a group that has characteristic
properties. Ex. Azo dyes are known for being strong, good all-round
properties, and cost-effective; while anthraquinone dyes are known for being
weak and expensive.
2. There are a manageable number of chemical groups.
3. It is the classification used most widely by both synthetic dye chemists and dye
technologists.
The twenty-six recognized types of dyes by chemical classification are as follows:
1. Nitroso
2. Nitro
3. Mono-, dis-, tris- and polyazo
4. Azoic
5. Stilbene
6. Carotenoid
7. Diphenylmethane (ketone
imine)
8. Triarylmethane
9. Xanthene
10. Acridine
11. Quinoline
12. Methine and polymethine
13. Thiazole
14. Indamines and indophenols
15. Azine
16. Oxazine
17. Thiazine
18. Sulphur
19. Aminoketone
20. Hydroxyketone
21. Anthraquinone
22. Indigoid
23. Phthalocyanine
24. Natural organic coloring
matters
25. Oxidation bases
26. Inorganic coloring matters
b. Classification by Usage or Application
Shreve enumerates the types of dyes according to its usage or application as
follows:
1. Acid dyes
Dyes termed as acid dyes are derived their name from being insoluble in acid
baths. These dyes are usually azo, triarylmethane or anthraquinone
complexes. Acid dyes are used for dyeing protein fibers such as wool, silk and
nylon. Acid dyes are also used in dyeing leather and paper.
From Knutson’s Synthetic Dyes for Natural Fibers, acid dyes can further
classified into:
e. Leveling acid or strong acid dye
f. Milling or weak acid dyes
g. Super milling or fast acid or neutral acid dyes
2. Azoic dyes
These “ice colors” are made right on the fiber by coupling diazotized materials
while in contact with the fibers. Low temperature keeps the diazonium
compound from decomposing until ready to couple. These are brilliant and
long-lasting and are used primarily for printing on cotton. Rayon, cellulose
acetate, and polyester could also be dyed using azoic dyes.
3. Basic dyes
Basic dyes are mostly amino and substituted amino compounds soluble in acid
and made insoluble by the solution being made basic. Most are triarylmethane
or xanthenes. These can be used to dye wool or cotton with a mordant, but are
usually used for duplicator inks, carbon paper, and typewriter ribbons. In
solvents other than water, they form writing and printing inks. Basic dyes can
also be used on polyacrylonitriles, modified nylons and polyesters.
4. Direct dyes
Direct dyes are water-soluble anionic dyes. These dyes are used to dye cotton
directly, that is, without the addition of a mordant. They are also used to dye
union goods (mixed cotton, and wool, or silk). Other direct dyes are used on
leather, paper, rayon and nylon.These are generally azo dyes, and their
solubility in the dye bath is often reduced by adding salt. Some are developed
on the fiber by forming the diazonium salt on the cloth then coupling to
increase insolubility. Most of the dyes in this class are polyazo compounds,
along with some stilbenes, phthalocyanines, and oxazines.
5. Disperse dyes
Modern synthetics are difficult to dye. Disperse dyes are applied as very finely
divided materials which are adsorbed onto the fibers with which the then form
a solid solution. Simple, soluble azo dyes can be used, but anolamine group is
commonly found in this group and aids both in dispersion and adsorption.
Disperse dyes are substantially water soluble and are used to dye polyester
but they can also be used to dye nylon, cellulose triacetate, and acrylic fibers.
In some cases, a dyeing temperature of 130°C is required, and a pressurized
dyebath is used. The very fine particle size gives a large surface area that aids
dissolution to allow uptake by the fiber. The dyeing rate can be significantly
influenced by the choice of dispersing agent used during the grinding.
6. Reactive dyes
These dyes react to form a covalent link between the dye and the cellulose
fiber which they are customarily used to dye. This produces goods of
outstanding wash-resistance. High-purity reactive dyes are also used in the
ink-jet printing of textiles. Reactive dyes can also be used on rayon and some
nylon. The principal chemical classes of reactive dyes are azo (including
metalized azo), triphendioxazine, phthalocyanine, formazan and
anthraquinone.
7. Fluorescent brightening dyes
Everyone knows what is meant by white, but its accurate definition and
description prove to be quite elusive. “Bluing” has been used for a very long
time to make yellowish laundry appear “whiter”. Greater brilliance can be
obtained with soap, textiles, plastics, paper, and detergents by the addition of
these “optical brighteners”. They absorb ultraviolet light and emit bright blues,
which give greatly improved whiteness. Brighteners are stilbenes with some
pyrazoles, coumarin and naphthalimides as well.
Reflecting pigments such as titanium dioxide are often added to paper to
improve its whiteness. Brighteners are helpful in improving the appearance of
recycled paper.
8. Food, drug, and cosmetic dyes
Food, drug and cosmetic dyes include those coming from anthraquinone, azo
and indigoid classes. Some of these dyes are from the class of carotenoid and
triaryl methane.
9. Mordant dyes
Some dyes combine with metallic salts to form highly insoluble colored
materials called lakes. These materials are usually used as pigments. If a cloth
made of cotton, wool, or other protein fiber is impregnated with an aluminum,
chromium, or iron salt and then contacted with a lake-forming dye, the metallic
precipitate forms in the fiber, and the colors become far more resistant t light
and washing. Substituent groups such as –OH and –COOH attached to azo or
anthraquinone nuclei are capable of reaction with metals to form mordant
dyes.
10. Solvent dyes
Solvent dyes or spirit-soluble dyes are water-insoluble but solvent-soluble
dyes that are devoid of polar solubilizing groups such as sulfonic acid,
carboxylic acid, or quaternary ammonium. These dyes are predominantly azo
and anthraquinone, but phthalocyanine and triarylmethane dyes are also used.
Solvent dyes are used for coloring plastics, gasoline, oils, shoe polishes,
lipsticks, and waxes.
11. Sulfur dyes
Sulfur dyes are a large, low-cost group of dyes which produce dull shades on
cotton. They have good fastness to light, washing, and acids but are very
sensitive to chlorine or hypochlorite.
12. Vat dyes
Vat dyes have chemical structures that are highly complex and most are
derivatives of anthraquinone and indigoid. Upon reduction, they become alkali-
soluble and colorless, and are called leuco vats. Vat dyes are applied mainly
to cellulosic fibers as alkaline bath, usually with sodium hydrogen sulfite.
Vat dyes are expensive and are used to color fabrics (cotton, rayon or wool)
that are washed often like men and women’s shirts. Some vats are supplied as
pastes for printing.
The best known vat dye is the indigo which makes dark (navy) shades. As a
dye for cotton denim, its lack of fastness seems to be prized as a fad.
Table 1: Usage classification of dyes
CLASS PRINCIPAL SUBSTRATES
METHOD OF APPLICATION CHEMICAL TYPES
Acid
nylon, wool, silk, paper, inks and leather
usually from neutral to acidic dyebaths azo (including premetallized), anthraquinone, triphenylmethane, azine, xanthenes, nitro and nitroso
Azoic components and compositions
cotton, rayon, cellulose acetate and polyester
fiber impregnated with coupling component and treated with a solution of stabilized diazonium salt
Azo
Basic paper, polyacrylonitrile,
modified nylon, polyester and inks
applied from acidic dyebaths cyanine, hemicyanine, diazahemicyanine, diphenylmethane, triaryl methane, azo, azine, xanthenes, acridine, oxazine, and anthraquinone
Direct cotton, rayon, paper,
leather, and nylon applied from neutral or slightly alkaline baths containing additional electrolyte
azo, phthalocyanine, stilbene, and oxazine
Disperse polyester, polyamide,
acetate, acrylic and plastics
fine aqueous dispersions often applied by high temperature/pressure or lower temperature carrier methods; dye may be padded on cloth and baked on or thermofixed
azo, anthraquinone, styryl, nitro and benzodifuranone
Fluorescent brighteners
soaps and detergents, all fibers, oils, paints, and plastics
from solution, dispersion or suspension in a mass
stilbene, pyrazoles, coumarin, and naphthalimides
Food, drug and cosmetic
foods, drugs, and cosmetics
----- azo, anthraquinone, carotenoid, and triaryl methane
Mordant wool, leather, and
anodized aluminum applied in conjunction with Cr salts azo and anthraquinone
Reactive cotton, wool, silk, and
nylon reactive site on dye reacts with functional group on fiber to bind dye covalently under influence of heat and ph
azo, anthraquinone, phthalocyanine, triphendioxazine, formazan, oxazine and basic
Solvent plastics, gasoline,
varnishes, lacquers, stains, inks, fats, oils, and waxes
dissolution in the substrate azo, triphenylmethane, anthraquinone, and phthalocyanine
Sulfur cotton and rayon aromatic substrate vatted with sodium
sulfide and reoxidized to insoluble sulfur-containing products on fiber
indeterminate structures
Vat cotton, rayon, and wool water insoluble dyes solubilized by
reducing with sodium hydrogen sulfite, then exhausted on fiber and reoxidized
anthraquinone (including polycyclic quinones) and indigoids
VI. NOMENCLATURE OF DYES
Two ways are available for naming dyes. Dyes are either named by
1. their commercial name or
2. by their Colour Index of C.I.
a. Commercial Name
Commercial names of dyes are usually made up of three parts:
3. A trademark used by the particular manufacturer to designate both the
manufacturer and the class of dye
4. Color
5. Series of letters and numbers used as a code by the manufacturer to define
more precisely the hue and also to indicate important properties of the dye
The common letters used by manufacturers to describe dyes are tabulated below:
LETTER MEANING
Hue R Reddish G Greenish B Bluish Dyeing and fastness properties W Washfast dye E Exhaust dye For solvent and disperse dyes A Lowest level of heatfastness B Mid level of heatfastness C Mid level of heatfastness D Highest level of heatfastness For reactive dyes M Warm-dyeing dye H Hot-dyeing dye
There are instances when some manufacturers designate a bluish red dye as Red
4B while other manufacturers use Violet 2R for the same dye. TO resolve such
problem, it is better to consult the pattern leaflets provided by the manufacturing
company.
b. Colour Index (C.I.)
It is not uncommon for a single dye to have multiple names if one follows the
nomenclature of dyes using the method in the previous section. The term fuchsin
was once called magenta and light green can also be called methyl green. To
avoid further confusion, it is better to use the Colour Index method in naming dyes.
The Colour Index or CI is basically a compendium of dyes prepared by the Society
of Dyers and Colourists and the American Association of Textile Chemists and
Colorists as previously mentioned under the Classification of Dyes. The CI comes
in a book and a CD form and it presents a specific system to identify individual
dyes.
The general way of identifying dyes using the Colour Index is given below.
The CI generic name (CI Name) identifies dyes using the pattern given above. Its
syntax is given as CI <application type> <hue> <identifying number>. Using the CI
Name enables the easy identification of the hue and dye type at a glance. The CI
Name, however, may vary from one manufacturer to another. A dye dubbed as CI
Direct Blue 99 from one company may not be identical to the CI Direct Blue 99 of
another company.
The CI number (Constitution number) identifies dyes following a specific,
identifying, five-digit number code. It is assigned to a dye when its chemical
structure has already been identified by the manufacturer. Dyes with similar
chemical class or structures are given similar CI numbers. The CI number is
generally used when identifying dyes to be used in staining methods to avoid
confusion.
An illustration of using both CI Name and CI Number to name a dye is shown
below.
Chemical structure:
Molecular formula: C33H20O4
Chemical Abstracts name: 16, 17-dimethoxydinaphthol[1,2,3-cd:3',2',1'-Im
perylene-5,10-dione]
Trivial name: jade green
C.I. name: C.I. Vat Green I
C.I. number: C.I. 59825
Application class: vat
Chemical clas : anthraquinone
CAS registry number: [128-58-5]
Commercial names: Solanthrene Green XBN, AVECIA,
Cibanone Brilliant Green, BF, 2BF, BFD,
CIBA-GEIGY Indanthrene Brilliant Green, B, FB
VII. EQUIPMENT AND DESIGN
The basic steps of dye (and intermediate) manufacture are shown below.
a. Reaction
The reactions involved in this step may either be as follows:
a. sulfonation,
b. halogenations,
c. amination,
d. diazotization, and
e. coupling
The reactor itself is usually the focal point of the plant, but this does not mean that
it is the most important part of the total manufacture, or that it absorbs most of the
capital or operational costs. The processes after the reaction are often termed as
workup stages. Workup stages differ from one product to another. For example,
intermediates require less finishing than dyes.
The specifications for the reaction vessel for the production of intermediates and
dyes are as follows:
Materials Charging
Reaction
Product Isolation
Product drying, grinding, and/or
finishing
a. The reaction is carried out in a bomb-shapes reaction vessel.
b. The reaction vessel may be made from cast iron, stainless steel, or steel lined
with rubber, glass (enamel), brick, or carbon blocks.
c. The volume of the reaction vessel is between 2-40 m3 (500-10 000 gallons).
d. The reaction vessel must be equipped with mechanical agitators,
thermometers, or temperature recorders, condensers, pH probes, and etc.
depending on the nature of the operation.
Jackets or coils may be used for the heating and cooling of the reactor. High-
boiling fluids (e.g. hot oil or Dowtherm), steam, or hot water may be used to raise
the temperature; while air, cold water, or chilled brine may be used to lower it.
Unjacketed vessels are often used for reactions in aqueous solutions. Heating may
be done through direct introduction of steam, and cooling may be done by addition
of ice. Heat exchangers can also be used. The reaction vessels normally span two
or more floors in a plant to facilitate ease of operation.
b. Product Isolation
Products are transferred from one piece of equipment to another by gravity flow,
pumping, or blowing with air or inert gas. Solid products are separated from liquids
using any of the following methods:
a. centrifuge
b. filter boxes
c. continuous belt filters
d. various designs of plate-and-frame or recessed-plate filter presses
c. Product drying, grinding, and/or finishing
In some cases products, usually in the form of pastes discharged from a filter, must
be dried. Even with optimization of physical form, the water content of pastes
varies from product to product in the range of 20-80 %.
Among the different drying methods employed are the following:
a. air or vacuum ovens
b. rotary dryers
c. spray dryers
d. drum dryers
The final stage in dye manufacture is grinding or milling. Dry grinding is usually
carried out in impact mills; considerable amounts of dust are generated and well-
established methods are available to control this problem. Dry grinding is an
inevitable consequence of oven drying, but more modern methods of drying,
especially continuous drying, allow the production of materials that do not require a
final comminution stage. The ball mill has been superseded by sand or bead mills.
Wet milling has become increasingly important for pigments and disperse dyes.
Many patented designs, particularly from Draiswerke GmbH and Gebruder
Netzsch, consist of vertical or horizontal cylinders equipped with high-speed
agitators of various configurations with appropriate continuous feed and discharge
arrangements.
Figure 1 below shows the layout of a typical azo dye manufacturing plant.
Figure 1: Layout of azo dye manufacturing plant. 1, storage tanks for liquid starting
materials; 2, storage drums for solid starting materials; 3, diazotisation vessel; 4,
coupling component vessel; 5, ice machine; 6, coupling vessel; 7. isolation vessel; 8.
filter presses; 9, filtrate to waste liquor treatment plant; 10, dryers; 11, emptying of
dyestuffs for feeding to the mill; 12, outgoing air purification plant.
d. Waste Characteristics
The principal air pollutants from dye manufacturing are as follows:
a. volatile organic compounds (VOCs),
b. nitrogen oxides (NOx)
c. hydrogen chloride (HCl)
d. sulfur oxides (SOx)
Liquid effluents from the cleaning of the equipments after batch operation can
contain toxic organic residues. Cooling water are normally recirculated.
Wastewater generation rate is usually 1-700 liters/kg of product except for vat
dyes. Vat dye production can generate wastewater of up to 8,000 L/kg of product.
Major solid wastes include:
a. filtration sludge
b. process and effluent treatment sludges
c. container residues
Other wastes that are considered toxic are,
a. wastewater treatment sludges
b. spent acids
c. process residues from the manufacture of chrome yellow and orange pigments,
molybdate orange pigments, zinc yellow pigments, chrome and chrome oxide
green pigments. Iron blue pigments and azo dyes
VIII. REFERENCES
Shreve, R. and Austin, G. Shreve’s Chemical Process Industries, 3rd ed. McGraw-Hill
Publishing, Inc. 1984
Hunger, K. Industrial Dyes, Chemistry, Properties, Applications, Wiley-VCH, 2003
http://www.uploadcity.com/?f=8837762&t=Fundamentals_of_Biochemical_Engineering.rar&
http://www.ifc.org/ifcext/enviro.nsf/AttachmentsByTitle/gui_dye_WB/$FILE/dye_PPAH.pdf
http://www.pburch.net/dyeing/aciddyes.shtml
http://www.morechemistry.com/publ/colours_dyes/slide094.html
http://www.dyespigments.com/colour-index.html
http://www.globalspec.com/reference/41765/203279/Nomenclature-of-Dyes
http://www.dyespigments.com/what-is-dye.html
http://218.6.128.157/excellentcourses/fccae/pdf_textbook/3_jxh_Dyes-a%20general%20servy