CFC and GA

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Chlorofluorocarbons andthe Ozone Layer

The Stratosphere and the Ozone Layer

The Ozone Layer

It refers to the ozone within stratosphere, where over 90% of the earth's ozone resides.

Ozone is an irritating, corrosive, colorless gas with a smellsomething like burning electrical wiring.

Ozone is easily produced by any high-voltage electrical arc(spark plugs, Van de Graaff generators, Tesla coils, arcwelders).

Each molecule of ozone has three oxygen atoms and isproduced when oxygen molecules (O2) are broken up byenergetic electrons or high energy radiation.

O + O 2 O3 It absorbs 97-99% of the sun's high frequency ultraviolet

light , light which is potentially damaging to life on earth. But worldwide, the ozone layer is thinning as the total

amount of ozone decreases. In 1985, the British Antarctic Survey team discovers

Antarctic Ozone Hole (7.3M square miles), marking the firstevidence of stratospheric Ozone Depletion.

Depletions in the ozone can cause sunburn, skin cancer andeye disease.

Causes of Ozone Layer Depletion

The following chemicals affect the Ozone layer:

Chlorofluorocarbons or CFCs main factor of Ozone depletion

Halons - are bromine-containing fluorocarbons that are used in fireextinguishers, although they may contribute to depletion of the ozonelayer

Bromomethane or Methyl Bromide (CH 3Br) a pesticide, and anagricultural fumigant but phase-out by many countries.

* In 1975, scientists discover that bromine, used in fire-retardinghalons and agricultural fumigants, is a potent ozone-depletingsubstance.

Chlorofluorocarbons

These are small gaseous molecules containing carbon,chlorine and fluorine.

It was first created in 1928 as non-toxic, non-flammablerefrigerants, and were first produced commercially in the1930's by DuPont.

Examples are CFCl 3 (Freon 11) and CF 2Cl2 (Freon 12)

These are widely used as:

Dry-cleaning solvents

Refrigerants for f reezers, airconditioners, and refrigerators

Propellant in aerosol cans

Foaming agents for plastics

In 1973, scientists detect CFCs in the atmosphere.

In 1974, Mario Molina and F. Sherwood Rowland published alaboratory study demonstrating the ability of CFC's tocatalytically breakdown Ozone in the presence of highfrequency UV light.

In 1970, Paul Crutzen, showed that naturally occurringnitrogen oxides catalytically destroy ozone.

In 1995 the Nobel Prize for Chemistry was awarded to thethree of them for their studies of ozone depletion in thestratosphere.

So why are CFCs harmful?

Because UV light causes CFCs todissociate and produce chlorine atoms,chlorine free radicals.

Chain Initiation: CF 2Cl2 CF2Cl + Cl

These chlorine atoms react to formchlorine monoxide and molecularoxygen, so a molecule of ozone isdestroyed.

Chain Propagation: Cl + O 3 ClO + O 2

But again chlorine monoxide reacts withnaturally occurring oxygen atoms toregenerate the original chlorine radicaland molecular oxygen.

ClO + O Cl + O 2

* A free radical chain reaction is initiated by each CFC that isdissociated, and each chain reaction results in the destruction of thousands of molecules of Ozone.

CFCs VS HCFCs/HFCs and other Alternatives

Why use HCFCs than CFCs?

Because HCFCs are less-threatening, energy-efficient, low-in-toxicity,cost effective and can be used safely.

Hydrogens on HCFCs make them more susceptible to oxidation anddestruction in the lower atmosphere.

HFCs have C H bonds rather than C-Cl bonds of CFCs

What are other Alternatives aside HCFCs /HFCs ?

We can also use gaseous hydrocarbons such as butane and propane

Action of the Society onCFC and its Effects

In 1976, the United Nations Environmental Programme(UNEP) calls for an international conference to discuss aninternational response to the ozone issue.

In 1978, U.S. bans non-essential uses of CFCs as propellantin some aerosols. Canada, Norway and Sweden follow withthe similar ban.

In 1981, UNEP develops a global convention to protect theozone layer.

The Montreal Protocol

In September 16, 1987, 24 countries sign the MontrealProtocol on Substances that Deplete the Ozone Layer.

An international treaty designed to protect the ozone layerby phasing out the production of a number of substancesbelieved to be responsible for ozone depletion

It undergone many revisions through the years, example isin in Copenhagen in November of 1992, laid down the moststringent CFC phase-out schedule for CFC's for the world todate; and was signed by over 100 nations r epresenting 95%of the world's current CFC consumption.

This protocol laid out a schedule for the phase-out of CFC'sand related halocarbons by the year 2030.

In 1988, Sweden was the first country to legislate thecomplete phase-out of CFC's, with a scheduled phase-out of CFC's in all new goods by 1994.

In 1990, an amended federal Clean Air Act was signed into

law. This legislation included a section (Title IV) entitledStratospheric Ozone Protection

In 1992, U.S. announces an accelerated CFC phase-out dateof December 31, 1995.

In 1993, Du Pont announces that it will stop its production of CFCs by the end of 1994.

In 1994, U.S. eliminates production and import of halons.

In 1996, U.S. eliminates production and import of CFCs ,carbon tetrachloride, trichloroethane, andhydrobromofluorocarbons.

In 2000, Japan Meteorological Agency reports the hole in thestratospheric ozone layer over Antarctica is as its largest todate more than twice the size of Antarctica.

In 2002, all developing countries freeze the production of Methyl Bromide.

In 2004, all developed countries reduce consumption of hydrochlorofluorocarbons (HCFCs) by 35% from baselinelevel.

In 2006, the ozone hole is reported to be the biggest ever,exceeding that of 2000.

In the year 2060 2075, earliest time frame of projected forthe ozone layer to recover.

GENERAL ANESTHETICS
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These are groups of relatively nontoxic, nonflammable,easily vaporized organic liquid used for this purpose.

Its effects is called General Anesthesia which is an inductionof a balanced state of unconsciousness, accompanied by theabsence of pain sensation and the paralysis of skeletalmuscle over the entire body.

These are used in persons undergoing a major surgery tokept them unconscious, without perception of sensations, fora controlled period of time without danger of death or toxicside effects.

Five distinct states during surgery:

analgesia, or pain relief

amnesia, or loss of memory of theprocedure

loss of consciousness

motionlessness

weakening of autonomic responses

Before giving General Anesthetics:

The medical personnel should know the medical history of the patientslike allergies.* Malignant Hyperthermia - potentially fatal allergic response toanesthesia

Consider many factors, including a patient's age, weight, allergies tomedications, medical history, and general health when deciding whichanesthetic or combination of anesthetics to use.

Why General Anesthetics can cause unconsciousness orAnesthesia?

Membranes of our bodies, including those of the nerve cellsin our brains, are largely hydrocarbon in structure, thenanesthetics can pass into our cells rapidly and exit just asquickly.

There are, however, several hypotheses that have beenadvanced to explain why general anesthesia occurs:

1. Meyer-Overton theory - suggests that anesthesia occurs when asufficient number of molecules of an inhalation anesthetic dissolve inthe lipid cell membrane.

2. The second theory maintains that protein receptors in the centralnervous system are involved, in that inhalation anesthetics inhibit theenzyme activity of proteins.

3. A third hypothesis, proposed by Linus Pauling in 1961, suggests thatanesthetic molecules interact with water molecules to form clathrates(hydrated microcrystals), which in turn inhibit receptor function.

Types of anesthetic agents

There are two major types of anesthetics used for general anesthesia,

Inhalation anesthetics

- are sometimes called volatile anesthetics, are compoundsthat enter the body through the lungs and are carried by theblood to body tissues.

- Less often used alone in recent clinical practice; they areusually used together with intravenous anesthetics.

Intravenous anesthetics

- giving medications or fluids (solutions) through a needle ortube inserted into a vein

INHALATION ANESTHETICS

Halothane

- Causes unconsciousness but provides little pain relief;often administered with analgesics

- It may be toxic to the liver in adults.

- has a pleasant smell and is therefore often theanesthetic of choice when mask induction is used withchildren.

- This halogenated hydrocarbon was first synthesisedby C. W. Suckling of Imperial Chemical Industries (ICI)in 1951 and was first used clinically by M. Johnstone inManchester in 1956.

Enflurane

- less potent, but produces a rapid onsetof anesthesia and possibly a fasterrecovery

- not used in patients with kidney failure

- Developed by Ross Terrell in 1963, itwas first used clinically in 1966.

Isoflurane

- not toxic to the liver but can induceirregular heart rhythms

Sevoflurane

- works quickly and can be administeredthrough a mask since it does not irritatethe airway

- On the other hand, one of thebreakdown products of sevoflurane cancause renal damage

Methoxyflurane

- was commonly used as an inhalationanesthatic in the 1960s and early 1970s

- As largely been abandoned because of detrimental effects on the kidneys

INTRAVENOUS ANESTHETICS

Ketamine

- produces a different set of reactionsfrom other intravenous anesthetics

- have sensory illusions and vivid dreamsduring post-operative recovery,ketamine is not often given to adultpatients

- useful in anesthetizing children, patientsin shock, and trauma casualties in warzones where anesthesia equipment maybe difficult to obtain

Thiopental (a barbiturate)

Methohexital

Etomidate

Propofol

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Nasal Decongestants, Diet Pills and Stimulants

All of us have had an adrenalin rush; adrenalin (epinephrine) isreleased by the human adrenal gland in times of stress, fear, orexcitement. Adrenalin belongs to a group of compounds sometimesreferred to as phenylalkylamines; these compounds have a benzenering, an alkyl group, and an amine group. A number of these bases arefound in the herb ma huang , which has been used medicinally in Chinafor more than 5000 years.
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The physiological effects we experience with adrenalin are common, invarying degrees, to other phenylalkylamines. For example, peyote,used in the religious rituals of Indian tribes in Mexico and legally in

religious ceremonies of the Native American Church in the UnitedStates, is a Mexican cactus that produces the hallucinogenic drugmescaline. Amphetamine (also called Dexedrine) was introduced in1932 as a nasal decongestant; it was used in World War II to keep frontline troops alert. Ritalin, a somewhat more complex phenylalkylamine,is used to assist children and adults in coping with diagnosed attentiondeficit disorder(ADD).

Many over the counter nasal decongestants, both topical and oral,contain phrnylalkylamines, most commonly ephedrine, phenylephrineand phenylpropanolamine hydrochloride.

These drugs function by contracting the arterioles within thenasal mucous membranes, thereby restricting blood flow to this area.Swelling is reduced, nasal passages are opened, and the ventilationand drainage of sinuses are possible. However , prolonged use of

decongestants, especially topical sprays, can result in restrictednutrient flow to the area and in reduced waste removal from thesinuses, leaving the affected tissues swollen and susceptible toinfection. Long duration nasal decongestants contain compounds thatlike xylometazoline hydrochloride, a compound that is structurallyrelated to phenylalkylamines.

Phenylpropanolamine hydrochloride is also used in diet pills,often in does similar to oral nasal decongestants. The appetitesuppressant effect of phenylalkylamines is at work here, but otherphysiological actions can lead to side effects. As consequence, oraldecongestants and diet pills containing phenylalkylaminehydrochloride often have printed cautions to people with heartproblems and diabetes.

Many oral nasal decongestants and allergy preparationscontaining antihistamines. When the body begins to experience anallergic reaction such as to pollen, insect stings, and many otherirritants, histamine is produced. Most symptoms of allergies arecaused by histamine. Antihistamine reduce or eliminate the effects of histamines. Some histamines are used as sleeping pills and sedatives,and many that treat allergies can cause drowsiness. Fexofenadine andloratadine are common prescription antihistamine that do not causedrowsiness because they do not prenetrate to the blood brain barrier.

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ASPRIRIN and other ANALGESICS

ANALGESICS (pain relievers) Among the most important medicinal applications of

carboxylic acid derivatives.ASPIRIN (acetyl salicylic acid)

One of the oldest analgesics, a drug that is amazing for its

continuing and varied usefulness Salicylic ester of acetic acid Reduces fever but does not lower normal body temperature Its analgesic properties are effective against pains

accompanying colds, flu, nervous tension, rheumatism,and arthritis.

Continuous small doses over a long periods could decreasethe chances of heart problems. And increase chances of surviving heart attack should one occur.

ASPIRIN Comes from that of a willow, Salix Spirea. Jesuit Missionaries

in the middle ages used the bark of this tree for medicinalpurposes.

7 th century- extracts of willow bark had fever-reducingproperties.

1826- salicylic acid was isolated 1852 - salicylic acid had been independently synthesized

1874-relatively large scale production had made it availableas medicine

SALYCLIC ACID A bifunctional molecule (acid & phenol) from which many

familiar substances are derived. Used as a disinfectant in some first aid sprays and

ointments. Its methyl ester, methyl salicylate (oil of wintergreen) is used for tropical rubs for some muscles.

Although an effective antipyretic, still causes severestomach irritation in some people. So the search for painrelievers continued in the late 1800s

It was hypothesized that the neutralized acid would causeless gastric irritation

1875- Sodium Salicylate was introduced.SALOL

A phenol ester of salicylic acid. Introduced in 1886. Its usedlead to greatly decreased incidence of gastric distress.

Hydrolyzes to sodium salicylate, which previously has beenused as pain reliever.

However, simultaneous liberation of phenol led to the dangerof phenol poisoning.

Felix Hoffman- who worked for the Bayer Company,investigated other derivatives of salicylic acid and testedacetyl salicylic acid on his father who suffered arthritis.

This & other tests revealed its excellent medicinal propertiesand a decreased frequency of gastric irr itation.

ACETYL SALICYLIC ACID, ASPIRIN- was marketed in 1899 bythe Bayer Company.

Unfortunately, even aspirin causes stomach distress in someindividuals, and minor, usually clinically unimportant, gastricor intestinal bleeding. Other products have been introducedthat do not have these unpleasant side effects.

The most familiar of these is ACETAMINOPHEN.ACETAMINOPHEN

Essentially equivalent to aspirin in their antipyretic andanalgesic properties.

PHENACITIN Has been implicated in Kidney damage, and though it was

once a popular ingredient in APC (aspirin and phenacetin and

caffeine) tablets, its use has been largely discontinued. IBUPROFEN In low strength doses, it is a relative newcomer to the

nonprescription pain reliever market, although it wasavailable as a prescription for some time.

SALICYLAMIDE Much less effective than aspirin and too weak and unreliable

to be generally useful as a pain reliever alone. Antacids are added to pain relievers to: raise gastric pH and thus minimize stomach upset and to accelerate tablet dissolution Antacids found in pain relievers or over-the-counter antacid

preparations include:NaHCO 3 (baking soda, bicarbonate, soda)CaCo 3 (calcium carbonate)Mg(OH) 2 (milk of magnesia)Al(OH) 3 (aluminum hydoxide)NaAl(OH) 2 CO 3 (dihydroxylaluminum sodium bicarbonate)

Neurotransmitters

Among the many relevant phenol derivatives, the catecholneurotransmitters are some of the most valuable and interesting.

The nervous system runs on a series of physical andchemical reactions. Signals are carried from one nerve cell to anotherby simple chemical molecules known as neurotransmitters .Epinephrine (adrenalin), norepinephrine, dopamine, and acetylcholineare but four of the more than 20 known neurotransmitters.

The first three substances are also called catecholamines

because they are similar to catechol, or o -hydroxyphenol The sympathet ic nervous system (SNS) and the

parasympathetic nervous system (PNS) stimulate almost every organ

in the body in a complementary fashion. The PNS supplies thestimulation for normal physiological functions, while the SNS providesthe necessary arousal for survival in the cold, cruel world.

The PNS is responsible for contraction of the pupils of theeyes, normal pulse and blood pressure, constriction of the bronchi,digestive enzyme-containing secretions in the mouth, and increasedgastrointestinal activity. The SNS in an effort to make the body alertand ready to respond to any outside threat, causes dilation of thepupils, increased pulse and blood pressure, and relaxation of thebronchi, dry mouth, and decreased gastrointestinal motility.

The prime neurotransmitter in the SNS is norepinephrine. Itis synthesized in an SNS nerve cell and, in response to a nerveimpulse, is secreted into the space between two nerve cells, called thesynapse . The neurotransmitter travels to the other side of the synapseand combines with a protein known as a receptor on the surface of thenext nerve cell. This triggers the nerve impulse in that cell.

-blockers :

2-receptor agonists :


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Low-Calorie Sweeteners

Provide sweet taste without calories, or with very fewcalories.Most low-calorie sweeteners are not digested by the bodyand provide no calories.

are also called "non-nutritive sweeteners"Glucose not needed for metabolic energy is either stored as:

GlycogenLipid

Can form on the walls of blood vessels,eventually leading to atherosclerosis, orincrease risk of stroke or heart attack.

Therefore, many persons limit intake of fat andcarbohydrates, especially sucrose.In order to satisfy sweet tooth developed by sugared diets,various natural and synthetic materials have been or arebeing investigated as sugar substitutes or enhancers.

Low-calorie Substitutes: Their ability to be absorbed in the intestine is minimal, buttheir capacity for hydrogen-bonding has caused them to be

associated with unpleasant laxative action of they areconsumed in large quantitiesExamples of these low-calorie substitutes are:

Sugar alcoholsMannitolSorbitol

Saccharin300 times sweeter than sucroseShown to promote cancer in laboratory animalsClassified as carcinogen: cancer-causing substanceEnhance the carcinogenicity of other substances

Aspartame200 times sweeter than sucroseA dipeptide composed of 2 amino acidsIllustrates that a molecule need not be a carbohydrate to besweetL-aspartyl-L-phenylalanyl-methyl ester

Lactose: The second unit of lactose, glucose, has its hemiacetalcarbon free and it can therefore open up to the aldose form.is a reducing sugar and will be oxidized by:

Fehlings reagentsBenedicts reagents

Tollens reagentsrequires: lactase - a special enzyme to break its glycosidicbond

- secreted in the intestines of youngmammals

Lactose intolerance is when adults cannot digest milk andmilk products - 70-80% of worldsadult population has this condition

- bring about gastrointestinal distress due tofermentation of undigested lactose byendogenous intestinal bacteria

- already fermented milk products like

yogurt and cheese are available for those who aresuffering- Lactaid is available as lactase enzyme to treat

milk- Sweet acidophilus a bacterium

which is Lactobacillus acidophilus- added to regular milk

Sucrose:also called the table disaccharide, the everyday tablesugarcomposed of glucose and fructose units joined by glycosidebonda nonreducing sugar because it will not give a positiveFehlings testAs a disaccharide, it is Dextrorotatory. Upon hydrolysis byacid or enzyme, optical rotation changes to Levorotatory asa result of release of fructose, also known as levulose andglucose, or dextrose units.Inversion sign optical activity changes from plus to minus

- caused by hydrolysis process and occurs on theoptical rotation

Invert sugar mixture of the two monosaccharidesInvertase enzyme contained in bees

- causes this conversion duringproduction of honey

- humans has this similar enzyme calledsucraseSucrose:

Known cause of extensive tooth decayPlaque material that sticks to our teethStreptococcus multans bacterial colonies thatcomposes plaque

Lactic acid end result of digestion of adhesivealong in the food in which bacteria produced usingsucrose

- causes the corrosion of the mineral deposits(hydroxyapati te) of the teeth anddestruction of gums

Errors in the Metabolism of Fatty Acids Lorenzos Oil

Lorenzos Oil:a 1992 movie that detailed the real-life struggle of theOdone family

the Odone family has a young son suffering from a metabolicdisorderLorenzo Odone show symptoms:

Personality disorderLoss of coordination and speech

The young son of Odone family suffered from ALDAdrenoleukodystrophy (ALD)

- an inborn metabolic disorder passed asan X-linked gene through the women in the family

- extremely rare condition 1 in 45,000in the populations of United States and Europe.

- accumulation of very-long-chain fattyacids (22-26 carbon range) in the brain and adrenalcortex

The OdonesBecame self-taught experts, finding a dietarysupplement of a 4:1 mixture of olive oil thatseemed to slow progress of ALD in their son.

The supplement contains: Oleic acid as major component Triglycerides of erucic acid 40-50% of

seeds of rapeseeds, mustard, wallflower,and nasturtium seeds

Lorenzos Oil mixture that seems to stabilize low bloodconcentrations of very-long-chain fatty acids and hasimpeded the development of ALD in some young patients

- normal course of affliction is about two yearsfrom diagnosis to death

- for some treated did not have their conditionrelieved

Augusto and Michaela Odone- their devotion and studies indicated some

possible avenues of research- Augusto is the current director of Myelin Project

DRUG DESIGN

An understanding of the effects of halogenation has beenuseful in the important area of drug designIn order to be effective a drug must be designed to reach itssite of action. In many cases, this involves penetration of oneor more membrane barriers between the site of applicationand the receptor location.Because the cell membrane is a lipid bilayer with a nonpolarinterior, it tends to resist penetration by molecules that arenot fat soluble; the more lipid soluble a molecule is, thebetter it will diffuse across the membrane. Such lipidsolubility can sometimes be increased by halogensubstitution.

Molecule Cortisol- a corticosteroid hormone secreted by the adrenal cortex.

Biological Functions :- Helps regulate carbohydrate and protein metabolism and salt

balance.- Inhibit inflammation.

Measuring Blood Alcohol

Determining the Level of Alcohol Concentration in the Blood by using aPerson's Breath

The alcohol is absorbed through the membranes in a person's mouth,throat, stomach, and intestines. Once absorbed by the body, thealcohol passes immediately into the bloodstream, where it circulatesuntil it is expelled through evaporation in the lungs. Evaporation occursbecause alcohol is "volatile" in a solution, meaning that its moleculesdo not combine with the liquid that it mixes with. Due to this volatility,as the blood passes through the lungs, some of the alcohol passes overthe alveoli (the lungs' air sacs), allowing it to be released by theperson's breath. The expulsion of the evaporated alcohol through thebreath permits the BAC to be accurately measured, since the percentalcohol being expelled contains the same level of alcohol that iscontained in the blood. The amount of alcohol in 2,100 ml of expelledbreath is exactly equivalent to the amount of alcohol in 1 ml of blood.

Breathalyzer Test- based on the oxidation of ethyl alcohol to acetic acid using potassiumdichromate.- test for estimating alcohol in the blood, whether administered in thefield by having the subject breathe into a plastic bag or more preciselyin a lab.A breathalyzer consists of a collection device, a "straw" attached to acylinder. The cylinder contains two vials, which contain a solution of sulfuric acid, potassium dichromate, silver nitrate and water. Theindividual being tested blows into the straw for approximately two tofour seconds. The object is to test the air from deep in the lungs, whichwill produce the most accurate reading. The expelled air travels intothe vials, where the silver nitrate acts as a catalyst to initiate andspeed up the analysis. The first thing that happens is that the sulfuric


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acid removes the alcohol from the air. The sulfuric acid also mightprovide the acidic condition needed for this reaction. During thisreaction, the reddish-orange dichromate ion changes color to the greenchromium ion when it reacts with the alcohol; the degree of the colorchange is directly related to the level of alcohol in the expelled air. Todetermine the amount of alcohol in that air, the reacted mixture iscompared to a vial of unreacted mixture in the photocell system, whichproduces an electric current that causes the needle in the meter tomove from its resting place. The operator then rotates a knob to bringthe needle back to the resting place and reads the level of alcohol fromthe knob -- the more the operator must turn the knob to return it torest, the greater the level of alcohol.

8 H 2 SO 4 + 3 C 2 H 5 OH + 2 K 2 Cr 2 O 7 3 CH 3 COOH +2 Cr 2(SO 4 ) 3 + 11 H 2 O + 2 K 2SO 4sulfuric acid ethanol potassium dichromate acetic acidchromium sulfate water potassium sulfate

Potassium Dichromate- a very vivid reddish-orange substance that changes into green as theethyl alcohol is oxidized and Cr 6+ of the orange red dichromate isreduced to green Cr3+Chromium Trioxide(CrO 3)- a dark red/orange brown water-soluble solid. It is stable by itself,however, it is a strong oxidant when mixed with other substances thatcan be oxidized.- a strong oxidizing agent that is not soluble in most organic solventsand tends to explode in the presence of organic compounds andsolvents. In water, it forms chromic acid and anhydrides, from whichsalts such as sodium dichromate (Na 2Cr 2O 7) and pyridinium dichromateare commercially available.Sodium Dichromate ( Na 2Cr 2O 7 )

- the salt is usually handled as its dihydrate (Na 2Cr 2O7 2H 2O)- poisonous red-orange crystalline compound used as an

oxidizing agent - Chromium Trioxide and sodium dichromate are common

oxidizing agents which oxidize primary alcohols tocarboxylic acids and secondary alcohol to ketones.

Pyridinium chlorochromate (PCC)- a reagent that stops the oxidation of primary alcohol at the

aldehyde stage

Dye and DyingCompounds that absorb one or more wavelengths of visible lightappear colored to the human eye. White light possesses allwavelenghts of visible light. When a beam of white light strikes acolored surface,certain wavelengths are absorbed and others arereflected,we see what is reflected.

The compound has a chromophore group ( a chemical group of

selective light absorption resulting in coloration of certain organiccompounds,also called color radical) There is an extensive network of alternating single and double bonds(conjugation) of which the chromophore is a part.

For a compound to be a dye,it must not only show color,it must also beable to adhere to a fabric. Auxochrome is a chemical group within adye molecule by which the dye is bound to reactive end group intissues. The auxochrome enhances the intensity of absorption.

Classification of dyesDIRECT DYESAny of a class of coloured,water-soluble compounds that have anaffinity for fiber and are taken up directly,such as the benzidinederivatives. Direct dyes are usually cheap and easily applied,and theycan yield bright colours. Washfastness is poor but may be improved byafter treatment. Silk and wool,can be colored simply by being dipped inthe dye (the dyes so used are consequently called direct dyes).MORDANT DYES

Dyes which require a mordant in their application and which uponcombination with the mordant deposit insoluble color on the substrate.e.g.,dyes with metal chelating groups. Mordants are substances of organic or inorganic origin which combine with the coloring matter andare used to fix the same in the production of the color. For the purposeof this class,such materials as oils and sulfonated oils, soaps, fats andhigher acids,are not generally considered as mordants.

REACTIVE DYESFiber reactive dyes are textile dyes which form a covalent bond withthe fibers of the textile,resulting in a long lasting,bright dye.-clothing colored with reactive dyes will not bleed in washing orfade.unless exposed to bright light.

INGRAIN DYEA colourant which is formed in suit in the substrate by thedevelopment and coupling of one or more intermediate compounds.

VAT DYEDyes such as indigo,that produces a fastcolor by impregnating fiber with a reduced soluble form that is thenoxidized to aninsoluble form. Applied by reducing the dye to a base-solubleform,applying the dye,theregenerating the insoluble dye by oxidation in he material,used fordyeing cotton using Vat or buckets. I t can be performed whenever aliquid,even shade over the entire garment is desired.

CHEM4(REPORT)aerbase.ayen/PHOTON

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CFC and GA