CHEMISTRY PROJECT ON:-***

***CHEMICAL FERTILIZERS

INSECTICIDESPESTICIDES

(HERBICIDES, D.D.T, NITROLIM, CHLOROPICRIN, UREA) ***

***SUBMITTED BY:-

KARUN JOHN SANTHOSHXII – C

ROLL NO – 17ST.THOMAS RESIDENTIAL SCHOOL

***

CONCLUSION

The production of chemical fertilizers, herbicides, insecticides and certain pesticides must be outlawed.  Chemical herbicides and pesticides kill bees and other pollinators.  Chemical fertilizers do not put minerals into the soil.  Consequently, the crops grown have very few minerals.  Vegetation alone has the unique ability to convert inorganic minerals absorbed from the soil and water into organic forms that animals and humans can use.  Because humans are at the top of the food chain, we are suffering the most.  Chemical fertilizers, herbicides and pesticides contaminate the air and water.  Top soil is not held in place, and it blows away.

If used properly then the advantages of these chemicals can benefit humans more without damaging the environment.

Even though chemistry gifted us these chemicals we must take good care not to over-use it and cause damage to our mother Earth.

***

INSECTICIDES

An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind the increase in agricultural productivity in the 20th century. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans; and others are concentrated in the food chain.

Classes of agricultural insecticides

The classification of insecticides is done in several different ways:

Systemic insecticides are incorporated by treated plants. Insects ingest the insecticide while feeding on the plants.

Contact insecticides are toxic to insects brought into direct contact. Efficacy is often related to the quality of pesticide application, with small droplets (such as aerosols) often improving performance.

Natural insecticides, such as nicotine, pyrethrum and neem extracts are made by plants as defences against insects. Nicotine based insecticides have been barred in the U.S. since 2001 to prevent residues from contaminating foods.[3]

Inorganic insecticides are manufactured with metals and include arsenates, copper compounds and fluorine compounds, which are now seldom used, and sulfur, which is commonly used.

Organic insecticides are synthetic chemicals which comprise the largest numbers of pesticides available for use today.

Mode of action – how the pesticide kills or inactivates a pest – is another way of classifying insecticides. Mode of action is

important in predicting whether an insecticide will be toxic to unrelated species, such as fish, birds and mammals.

Heavy metals, e.g. arsenic have been used as insecticides; they are poisonous and very rarely used now by farmers.

Commonly used class of insecticides

Organochlorine compounds Organophosphates Carbamates Pyrethroids Neonicotinoids Biological insecticides

Antifeedants

Many plants have evolved substances, like polygodial, which prevent insects from eating, but do not kill them directly. The insect often remains nearby, where it dies of starvation. Since antifeedants are nontoxic, they would be ideal as insecticides in agriculture. Much agrochemical research is devoted to make them cheap enough for commercial use.

HERBICIDES

An herbicide is a substance used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant hormones. Herbicides used to clear waste ground, industrial sites, railways and railway embankments are non-selective and kill all plant material with which they come into contact. Smaller quantities are used in forestry, pasture systems, and management of areas set aside as wildlife habitat.

Some plants produce natural herbicides, such as the genus Juglans (walnuts), or the tree of heaven; the study of such natural herbicides, and other related chemical interactions, is called allelopathy.

Classification of herbicides

Herbicides can be grouped by activity, use, chemical family, mode of action, or type of vegetation controlled.

By activity:

Contact herbicides destroy only the plant tissue in contact with the chemical. Generally, these are the fastest acting herbicides. They are less effective on perennial plants, which are able to regrow from rhizhomes, roots or tubers.

Systemic herbicides are translocated through the plant, either from foliar application down to the roots, or from soil application up to the leaves. They are capable of controlling perennial plants and may be slower acting but ultimately more effective than contact herbicides.

By use:

Soil-applied herbicides are applied to the soil and are taken up by the roots and/or hypocotyl of the target plant. There are three main types of soil-applied herbicides:

Major herbicides in use today

2,4-D , a broadleaf herbicide in the phenoxy group used in turf and in no-till field crop production. Now mainly used in a blend with other herbicides that allow lower rates of herbicides to be used, it is the most widely used herbicide in the world, third most commonly used in the United States. It is an example of synthetic auxin (plant hormone).

aminopyralid is a broadleaf herbicide in the pyridine group, used to control broadleaf weeds on grassland, such as docks, thistles and nettles. Notorious for its ability to persist in compost.

atrazine , a triazine herbicide used in corn and sorghum for control of broadleaf weeds and grasses. Still used because of its low cost and because it works extrodinarily well on a broad spectrum of weeds common in the U.S. corn belt, Atrazine is commonly used with other herbicides to reduce the over-all rate of atrazine and to lower the for potential groundwater contamination, it is a photosystem II inhibitor.

Environmental effects of Herbicides & Insecticides

Effects on nontarget species

Some insecticides kill or harm other creatures in addition to those they are intended to kill. For example, birds may be poisoned when they eat food that was recently sprayed with insecticides or when they mistake insecticide granules on the ground for food and eat it.

Sprayed insecticides may drift from the area to which it is applied and into wildlife areas, especially when it is sprayed aerially. Herbicides have widely variable toxicity. In addition to acute toxicity from high exposures there is concern of possible carcinogenicity as well as other long-term problems such as contributing to Parkinson's Disease.

Some herbicides cause a range of health effects ranging from skin rashes to death.The pathway of attack can arise from intentional or unintentional direct consumption, improper application resulting in the herbicide coming into direct contact with people or wildlife, inhalation of aerial sprays, or food consumption prior to the labeled pre-harvest interval. Under extreme conditions herbicides can also be transported via surface runoff to contaminate distant water sources. Most herbicides decompose rapidly in soils via soil microbial decomposition, hydrolysis, or photolysis.

PESTICIDES

A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest. A pesticide may be a chemical substance, biological agent (such as a virus or bacterium), antimicrobial, disinfectant or device used against any pest. Pests include insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes (roundworms), and microbes that destroy property, spread disease or are a vector for disease or cause a nuisance. Although there are benefits to the use of pesticides, there are also drawbacks, such as potential toxicity to humans and other animals. Pesticides also defined as:

any substance or mixture of substances intended for preventing, destroying or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals causing harm during or otherwise interfering with the production, processing, storage, transport or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs, or substances which may be administered to animals for the control of insects, arachnids or other pests in or on their bodies. The term includes substances intended for use as a plant growth regulator, defoliant, desiccant or agent for thining fruit or preventing the premature fall of fruit, and substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport.

History

Since before 20 BC, humans have utilized pesticides to protect their crops. The first known pesticide was elemental sulfur dusting used in ancient Sumer about 4,500 years ago in ancient Mesopotamia. By the 15th century, toxic chemicals such as arsenic, mercury and lead were being applied to crops to kill pests. In the 17th century, nicotine sulfate was extracted from tobacco leaves for use as an insecticide. The 19th century saw the introduction of two more natural pesticides, pyrethrum, which is derived from chrysanthemums, and rotenone, which is derived from the roots of tropical vegetables. Until the 1950s, arsenic-based pesticides were dominant.[4] Paul Müller discovered that DDT was a very effective insecticide. Organochlorines such as DDT were dominant, but they were replaced by organophosphates and carbamates by 1975. Since then, pyrethrin compounds have become the dominant insecticide.

Classification

Pesticides can be classified by target organism, chemical structure, and physical state. Pesticides can also be classed as inorganic, synthetic, or biologicals (biopesticides), although the distinction can sometimes blur. Biopesticides include microbial pesticides and biochemical pesticides. Plant-derived pesticides, or "botanicals", have been developing quickly. These include the pyrethroids, rotenoids, nicotinoids, and a fourth group that includes strychnine and scilliroside.

Pesticides can be classified based upon their biological mechanism function or application method. Most pesticides work by poisoning pests. A systemic pesticide moves inside a plant following absorption by the plant. With insecticides and most fungicides, this movement is

usually upward (through the xylem) and outward. Increased efficiency may be a result. Systemic insecticides, which poison pollen and nectar in the flowers, may kill bees and other needed pollinators.

Uses

Pesticides are used to control organisms considered harmful. For example, they are used to kill mosquitoes that can transmit potentially deadly diseases like west nile virus, yellow fever, and malaria. They can also kill bees, wasps or ants that can cause allergic reactions. Insecticides can protect animals from illnesses that can be caused by parasites such as fleas. Pesticides can prevent sickness in humans that could be caused by mouldy food or diseased produce. Herbicides can be used to clear roadside weeds, trees and brush. They can also kill invasive weeds that may cause environmental damage. Herbicides are commonly applied in ponds and lakes to control algae and plants such as water grasses that can interfere with activities like swimming and fishing and cause the water to look or smell unpleasant. Uncontrolled pests such as termites and mould can damage structures such as houses. Pesticides are used in grocery stores and food storage facilities to manage rodents and insects that infest food such as grain. Each use of a pesticide carries some associated risk.

Pesticides can save farmers' money by preventing crop losses to insects and other pests; in the U.S., farmers get an estimated fourfold return on money they spend on pesticides.

DDT, sprayed on the walls of houses, is an organochloride that has been used to fight malaria since the 1950s.

Environmental effects

Pesticide use raises a number of environmental concerns. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non-target species, air, water and soil. Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides are one of the causes of water pollution, and some pesticides are persistent organic pollutants and contribute to soil contamination.

In addition, pesticide use may also reduce biodiversity, reduce nitrogen fixation,contribute to pollinator decline, can reduce habitat, especially for birds, and can threaten endangered species.

Pesticide runoff is one of the most significant effects of pesticide use. The USDA Natural Resources Conservation Service tracks the environmental risk posed by pesticide water contamination from farms, and its conclusion has been that "the Nation's pesticide policies during the last twenty six years have succeeded in reducing overall environmental risk, in spite of slight increases in area planted and weight of pesticides applied. Nevertheless, there are still areas of the country where there is no evidence of progress, and areas where risk levels for protection of drinking water, fish, algae and crustaceans remain high".

Health effects

Pesticides can be dangerous to consumers, workers and close bystanders during manufacture, transport, or during and after use.

The American Medical Association recommends limiting exposure to pesticides and using safer alternatives:

Particular uncertainty exists regarding the long-term effects of low-dose pesticide exposures. Current surveillance systems are inadequate to characterize potential exposure problems related either to pesticide usage or pesticide-related illnesses…Considering these data gaps, it is prudent…to limit pesticide exposures…and to use the least toxic chemical pesticide or non-chemical alternative.

Consumers

There are concerns that pesticides used to control pests on food crops are dangerous to people who consume those foods. These concerns are one reason for the organic food movement. Many food crops, including fruits and vegetables, contain pesticide residues after being washed or peeled. Chemicals that are no longer used but that are resistant to breakdown for long periods may remain in soil and water and thus in food.

The public

Exposure routes other than consuming food that contains residues, in particular pesticide drift, are potentially significant to the general public.

The Bhopal disaster occurred when a pesticide plant released 40 tons of methyl isocyanate (MIC) gas, a chemical intermediate in the synthesis of some carbamate pesticides. The disaster immediately

killed nearly 3,000 people and ultimately caused at least 15,000 deaths.[

In China, an estimated half million people are poisoned by pesticides each year, 500 of whom die.

Alternatives

Alternatives to pesticides are available and include methods of cultivation, use of biological pest controls (such as pheromones and microbial pesticides), genetic engineering, and methods of interfering with insect breeding. Application of composted yard waste has also been used as a way of controlling pests. These methods are becoming increasingly popular and often are safer than traditional chemical pesticides. In addition, EPA is registering reduced-risk conventional pesticides in increasing numbers.

Cultivation practices include polyculture (growing multiple types of plants), crop rotation, planting crops in areas where the pests that damage them do not live, timing planting according to when pests will be least problematic, and use of trap crops that attract pests away from the real crop.

Release of other organisms that fight the pest is another example of an alternative to pesticide use. These organisms can include natural predators or parasites of the pests. Biological pesticides based on entomopathogenic fungi, bacteria and viruses cause disease in the pest species can also be used.

Another alternative to pesticides is the thermal treatment of soil through steam. Soil steaming kills pest and increases soil health.

In India, traditional pest control methods include using Panchakavya, the "mixture of five products." The method has recently experienced a resurgence in popularity due in part to use by the organic farming community.

DDT

IUPAC NAME 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane

Molecular formula C14H9Cl5Molar mass 354.49 g/molDensity 0.99 g/cm³Melting point 109 °CBoiling point decomp.

DDT (from its trivial name, dichlorodiphenyltrichloroethane) is one of the most well-known synthetic pesticides. It is a chemical with a long, unique, and controversial history.

First synthesized in 1874, DDT's insecticidal properties were not discovered until 1939, and it was used with great success in the second half of World War II to control malaria and typhus among civilians and troops. The Swiss chemist Paul Hermann Müller was awarded the Nobel Prize in Physiology or Medicine in 1948 "for his discovery of the high efficiency of DDT as a contact poison against several arthropods." After the war, DDT was made available for use as an agricultural insecticide, and soon its production and use skyrocketed.

Properties and chemistry

DDT is an organochlorine, similar in structure to the insecticide methoxychlor and the acaricide dicofol. It is a highly hydrophobic, colorless, crystalline solid with a weak, chemical odor. It is nearly insoluble in water but has a good solubility in most organic solvents, fats, and oils. DDT does not occur naturally, but is produced by the reaction of chloral (CCl3CHO) with chlorobenzene (C6H5Cl) in the presence of sulfuric acid, which acts as a catalyst.

Mechanism of action

In insects, it has potent insecticidal properties, where it kills by opening sodium ion channels in the neurons, causing them to fire spontaneously leading to spasms and eventual death. Insects with certain mutations in their sodium channel gene are resistant to DDT

and other similar insecticides. DDT resistance is also conferred by up-regulation of genes expressing cytochrome P450 in some insect species.

First synthesized in 1874 by Othmar Zeidler,[3] DDT's insecticidal properties were not discovered until 1939 by the Swiss scientist Paul Hermann Müller, who was awarded the 1948 Nobel Prize in Physiology and Medicine for his efforts.

Environmental impact

Degradation of DDT to form DDE (by elimination of HCl, left) and DDD (by reductive dechlorination, right)

DDT is a persistent organic pollutant that is extremely hydrophobic and strongly absorbed by soils. Depending on conditions, its soil half life can range from 22 days to 30 years. Routes of loss and degradation include runoff, volatilization, photolysis and aerobic and anaerobic biodegradation. When applied to aquatic ecosystems it is quickly absorbed by organisms and by soil or it evaporates, leaving little DDT dissolved in the water itself. Its breakdown products and metabolites, DDE and DDD, are also highly persistent and have similar chemical and physical properties. These products together are known as "total DDT". DDT and its breakdown products are transported from warmer regions of the world to the Arctic by the phenomenon of global distillation, where they then accumulate in the region's food web.

Effects on wildlife and eggshell thinning

DDT is toxic to a wide range of animals in addition to insects. It is highly toxic to aquatic life, including crayfish, daphnids, sea shrimp and many species of fish. It is less toxic to mammals, but may be moderately toxic to some amphibian species, especially in the larval stages. Most famously, it is a reproductive toxicant for certain birds species, and it is a major reason for the decline of the bald eagle, brown pelican peregrine falcon, and osprey. Birds of prey, waterfowl,

and song birds are more susceptible to eggshell thinning than chickens and related species, and DDE appears to be more potent than DDT.

Effects on human health

Potential mechanisms of DDT on humans are genotoxicity and endocrine disruption. DDT may have direct genotoxicity, but may also induce enzymes that produce other genotoxic intermediates and DNA adducts. It is an endocrine disruptor; The DDT metabolite DDE acts as an antiandrogen (but not as an estrogen). o,p'-DDT, a minor component in commercial DDT has weak estrogenic activity. However, p,p'-DDT, the main component of DDT, has little or no androgenic or estrogenic activity.[41]

Other

Occupational exposure to DDT (either as a farmer or a malaria control worker) has been linked to:

Neurological problems Asthma

UREA

Urea is an organic compound with the chemical formula (N H 2)2C O . The molecule has two amine (-NH2) residues joined by a carbonyl (-CO-) functional group.

Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. Being solid, colourless, odorless (although the ammonia which it gives off in the presence of water, including water vapor in the air, has a strong odor), neither acidic nor alkaline, highly soluble in water, and relatively non-toxic, urea is widely used in fertilizers as a convenient source of nitrogen. Urea is also an important raw material for the chemical industry. The synthesis of this organic

compound by Friedrich Wöhler in 1828 from an inorganic precursor was an important milestone in the development of chemistry.

History

Urea was first discovered in urine in 1773 by the French chemist Hilaire Rouelle. In 1828, the German chemist Friedrich Wöhler obtained urea by treating silver isocyanate with ammonium chloride in a failed attempt to prepare ammonium cyanate:

AgNCO + NH4Cl → (NH2)2CO + AgCl

This was the first time an organic compound was artificially synthesized from inorganic starting materials, without the involvement of living organisms. The results of this experiment implicitly discredited vitalism: the theory that the chemicals of living organisms are fundamentally different from inanimate matter. This insight was important for the development of organic chemistry. For this discovery, Wöhler is considered by many the father of organic chemistry.

Uses

Agriculture

More than 90% of world production of urea is destined for use as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use (46.7%). Therefore, it has the lowest transportation costs per unit of nitrogen nutrient.

In the soil, it hydrolyses to ammonia and carbon dioxide. The ammonia is oxidized by bacteria in the soil to nitrate which can be absorbed by the plants. Urea is also used in many multi-component solid fertilizer formulations. Urea is highly soluble in water and is, therefore, also very suitable for use in fertilizer solutions (in combination with ammonium nitrate: UAN), e.g., in 'foliar feed' fertilizers. For fertilizer use, granules are preferred over prills because of their narrower particle size distribution which is an advantage for mechanical application.

Because of the high nitrogen concentration in urea, it is very important to achieve an even spread. The application equipment must be correctly calibrated and properly used. Urea dissolves in water for application as a spray or through irrigation systems.

In irrigated crops, urea can be applied dry to the soil, or dissolved and applied through the irrigation water. Urea will dissolve in its own

weight in water, but it becomes increasingly difficult to dissolve as the concentration increases. Dissolving urea in water is endothermic, causing the temperature of the solution to fall when urea dissolves.

Chemical industry

Urea is a raw material for the manufacture of many important chemical compounds, such as

Various plastics, especially the urea-formaldehyde resins. Various adhesives, such as urea-formaldehyde or the urea-

melamine-formaldehyde used in marine plywood. Potassium cyanate , another industrial feedstock. Urea nitrate , an explosive.

Automobile systems

Urea is used in SNCR and SCR reactions to reduce the NOx pollutants in exhaust gases from combustion from diesel, dual fuel, and lean-burn natural gas engines. The BlueTec system, for example, injects water-based urea solution into the exhaust system. The ammonia produced by the hydrolysis of the urea reacts with the nitrogen oxide emissions and is converted into nitrogen and water within the catalytic converter.

Other commercial uses

A stabilizer in nitrocellulose explosives. A component of animal feed, providing a relatively cheap source

of nitrogen to promote growth. A non-corroding alternative to rock salt for road de-icing, and the

resurfacing of snowboarding halfpipes and terrain parks. A flavor-enhancing additive for cigarettes. A main ingredient in hair removers such as Nair or Veet. A flame-proofing agent, commonly used in dry chemical fire

extinguisher charges such as the urea-potassium bicarbonate mixture.

An ingredient in many tooth whitening products. An ingredient in dish soap. Along with ammonium phosphate, as a yeast nutrient, for

fermentation of sugars into ethanol. A nutrient used by plankton in ocean nourishment experiments

for geo engineering purposes. As an additive to extend the working temperature and open time

of hide glue.

As a solubility-enhancing and moisture-retaining additive to dye baths for textile dyeing or printing.

Medical use

Urea is used in topical dermatological products to promote rehydration of the skin. If covered by an occlusive dressing, 40% urea preparations may also be used for nonsurgical debridement of nails. This drug is also used as an earwax removal aid.

Certain types of instant cold packs (or ice packs) contain water and separated urea crystals. Rupturing the internal water bag starts an endothermic reaction and allows the pack to be used to reduce swelling.

Like saline, urea injection is used to perform abortions. Urea is the main component of an alternative medicinal

treatment referred to as urine therapy. The blood urea nitrogen (BUN) test is a measure of the amount

of nitrogen in the blood that comes from urea. It is used as a marker of renal function.

Synthetic production

Urea is produced on a scale of some 100,000,000 tons per year worldwide.

Industrial methods

For use in industry, urea is produced from synthetic ammonia and carbon dioxide. Large quantities of carbon dioxide are produced during the manufacture of ammonia from coal or from hydrocarbons such as natural gas and petroleum-derived raw materials. Such point sources of CO2 facilitate direct synthesis of urea.

The basic process, developed in 1922, is also called the Bosch-Meiser urea process after its discoverers. The various urea processes are characterized by the conditions under which urea formation takes place and the way in which unconverted reactants are further processed. The process consists of two main equilibrium reactions, with incomplete conversion of the reactants. The first is an exothermic reaction of liquid ammonia with dry ice to form ammonium carbamate (H2N-COONH4):

2 NH3 + CO2 ↔ H2N-COONH4 ()

Laboratory processes

Ureas in the more general sense can be accessed in the laboratory by reaction of phosgene with primary or secondary amines, proceeding through an isocyanate intermediate. Non-symmetric ureas can be accessed by reaction of primary or secondary amines with an isocyanate.

Chemical properties

Molecular and crystal structure

The urea molecule is planar. In solid urea, the oxygen center is engaged in two N-H-O hydrogen bonds. The resulting dense and energetically favourable hydrogen-bond network is probably established at the cost of efficient molecular packing: The structure is quite open, the ribbons forming tunnels with square cross-section. The carbon in urea is described as sp2 hybridized, the C-N bonds have significant double bond character, and the carbonyl oxygen is basic compared to, say, formaldehyde. Urea's high aqueous solubility reflects its ability to engage in extensive hydrogen bonding with water.

By virtue of its tendency to form a porous frameworks, urea has the ability to trap many organic compounds. In these so-called clathrates, the organic "guest" molecules are held in channels formed by interpenetrating helices comprising of hydrogen-bonded urea molecules. This behaviour can be used to separate mixtures, e.g. in the production of aviation fuel and lubricating oils, and in the separation of paraffins.

Reactions

Urea reacts with alcohols to form urethanes. Urea reacts with malonic esters to make barbituric acids.

Safety

Urea can be irritating to skin, eyes, and the respiratory tract. Repeated or prolonged contact with urea in fertilizer form on the skin may cause dermatitis.

High concentrations in the blood can be damaging. Ingestion of low concentrations of urea, such as are found in typical human urine, are not dangerous with additional water ingestion within a

reasonable time-frame. Many animals (e.g., dogs) have a much more concentrated urine and it contains a higher urea amount than normal human urine; this can prove dangerous as a source of liquids for consumption in a life-threatening situation (such as in a desert).

CHLOROPICRIN

Molecular formula CCl3NO2

Molar mass 164.375Appearance colorless liquidMelting point -69 °CBoiling point 112 °C (dec)

Chloropicrin, also known as PS, is a chemical compound with the structural formula Cl3CNO2. This colourless highly toxic liquid was once used in chemical warfare and is currently used as a fumigant and nematocide.

History

Chloropicrin was first discovered in 1848 by a Scottish chemist John Stenhouse. He prepared it by the reaction of a chlorinating agent with picric acid:

HOC6H2(NO2)3 + 10 NaOCl → 3 Cl3CNO2 + 3 NaOH + NaCl + 3 CO2

Because of the precursor he used, Stenhouse named the compound chloropicrin, although the two compounds are structurally dissimilar.

Arguably, chloropicrin's most famous use was in World War I. In 1917, there were reports that the Germans were testing and using a new chemical in warfare. That chemical was chloropicrin. While not as lethal as other chemical weapons, it caused vomiting and was a lachrymatory agent. This combination of properties forced Allied soldiers to remove their masks to vomit, exposing them to toxic gases. This caused a large number of casualties on the Italian front.

Preparation

Chloropicrin is manufactured by the reaction of nitromethane with sodium hypochlorite:

H3CNO2 + 3 NaOCl → Cl3CNO2 + 3 NaOH

Properties

As listed in the Table, chloropicrin is a colorless liquid that is insoluble in water, with which it is stable. With a vapor pressure of 24 mm Hg, its volatility is between that of phosgene and mustard gas in persistency, although closer to phosgene because it is related to the compound. Tests have shown that chloropicrin causes humans to shut their eyes involuntarily. Chloropicrin can be absorbed systemically through inhalation, ingestion, and the skin. It is severely irritating to the lungs, eyes, and skin. Because of these properties, chloropicrin can only be delivered in shell form as a chemical weapon.

Application

Chloropicrin, today, is used as a fumigant to control pests found in the soil. Although less common it can be used as a poison for vertebrates, such as rabbits. Chloropicrin is commonly used in combination with other fumigants, such as methyl bromide and sulfuryl fluoride, for increased potency and as a warning agent.

Chloropicrin has been used in chemical warfare. It first appeared in 1917 when the Germans tested a new chemical weapon on the Italian front. The new chemical weapon was devastating to the Allies at first, since they had never encountered it before.

Safety

Chloropicrin is a highly toxic chemical Examples of industrial exposure in humans: 27 workers in a

cellulose factory who were exposed to high levels of chloropicrin for 3 minutes developed pneumonitis after 3 to 12 hours of irritated coughing and difficulty on breathing; they subsequently devloped pulmonary oedema and one died.

Because of chloropicrin's stability, protection requires highly effective absorbents, such as activated charcoal. Chloropicrin,

unlike its relative compound phosgene, is absorbed readily at any temperature, which may pose a threat in low or high temperature climates

CALCIUM CYANAMIDE [NITROLIM]

IUPAC name [hide] Calcium cyanamideOther names[hide]

Cyanamide calcium salt, Lime Nitrogen, UN 1403, Nitrolime

Molecular formula

CaCN2

Molar mass 80.102 g/mol

Appearance White solid (Often gray or black from impurities)

Odor odorlessDensity 2.29 g/cm3

Melting point 1340 °C [1]

Boiling point 1150-1200 °C (sublim.)Solubility in water

Reacts

Flash point Non-flammableRelated compounds

CyanamideCalcium carbide

Calcium cyanamide or CaCN2 is a calcium compound used as fertiliser, first synthesized in 1898 by Adolph Frank and Nikodem Caro. It is formed when calcium carbide reacts with nitrogen. It is commercially known as Nitrolim.

CaC2 + N2 → CaCN2 + C

The reaction takes place in large steel chambers. An electric carbon element heats the reactants to red heat. Nitrogen is pressurised at 2 atmospheres.

Preparation

Calcium cyanamide is prepared from calcium carbide. The carbide powder is heated at about 1,000°C in an electric furnace into which nitrogen is passed for several hours. The product is cooled to ambient temperatures and any unreacted carbide is leached out cautiously with water.

CaC2 + N2 → CaCN2 + C (ΔHƒ°= –69.0 kcal/mol at 25°C)

Uses

The main use of calcium cyanamide is in agriculture as a fertilizer. In contact with water it decomposes and liberates ammonia:

CaCN2 + 3 H2O → 2 NH3 + CaCO3

It was used to produce sodium cyanide by fusing with sodium carbonate, which was used in cyanide process in gold mining:

CaCN2 + Na2CO3 → 2 NaCN + CaO + O2

It can also be used in the preparation of calcium cyanide and melamine.

http://en.wikipedia.org/wiki/File:Cropduster_spraying_pesticides.jpg

ACKNOWLEDGEMENT

I take this opportunity to thank my Chemistry teachers Mrs. Poonam Lal & Mrs. Solly Varghese for allowing me to do this project. I thank my friends and my parents who have helped and motivated me. Last but not the least I thank God for helping me complete this project on time