Product profiles under the Pesticides are aimed at giving an overview to readers about eleven major pesticides produced by the pesticides industry in India.

In this chapter, the chemicals are presented in the following order:
A. DDT
B. Malathion
C. Endosulfan
D. Triazophos
E. Monocrotophos
F. DDVP
G. Cypermethrin
H. Acephate
I. Chlorpyriphos
J. Phorate
K. Mancozeb

A. DDT

DDT or Dichlorodiphenyltrichloroethane is an organchlorine compound and is used as an insecticide to control agricultural pests and malaria vectors such as mosquitoes. In 1989, DDT was completely banned from being used in the agricultural sector but restricted use for public health purposes was permitted. Apart from public health, DDT is also produced and used as an intermediate in the manufacture of dicofol (with DDT as impurity not exceeding 0.1%) which is an organchlorine pesticide sharing a similar chemical structure to DDT.

Preparation of DDT

Alcohol is chlorinated to produce chloral alcoholate which is then distilled in presence of oleum to produce chloral. Chloral and monochlorobenzene are condensed in the presence of oleum to produce DDT. The technical grade DDT is further processed into water dispersible powder by particle size reduction after mixing with materials like china clay and wetting and dispersing agents.

Major Producers of DDT

Hindustan Insecticide Ltd (HIL) is the sole manufacturer of DDT in India.

B. Malathion

Malathion is an organophosphate (OP) insecticide that does not occur naturally and is used in agriculture, residential gardens, public recreation areas and in public health pest control programs. Malathion in low doses (0.5% preparations) is also used as a treatment for head lice, body lice, and scabies. When applied in accordance with the rate of application and safety precautions specified on the label, malathion can be used to kill mosquitoes without posing unreasonable risks to human health or the environment.

Preparation of Malathion

The process description for manufacturing of Malathion is furnished below:

DDPA Preparation

Phosphorus penta sulphide reacts with methanol to produce Dimethyl-Dithiophosphoric Acid (DDPA).

DEM Preparation

Maleic anhydride is reacted with ethyl alcohol in presence of benzene and catalytic amount of sulphuric acid. The water formed is removed azeotropically and then the solvent is distilled out. The diethyl-maleate (DEM) is neutralised and purified.

Malathion Preparation

It is manufactured by the condensation reaction (at 70-80 degrees Celcius) of dithio-phophoric acid (DDPA) and diethymaleate (DEM) in the presence of catalyst. The excess acidity is neutralised using dilute caustic solution and then washed with water. The solvent and moisture is removed under vacuum and dry Malathion tech is then packed.

Major Producers of Malathion

Some of the major manufacturers of Malathion are Cyanamid Agro Ltd, Hindustan Insecticides Ltd, Shivalik Rasayan Ltd, Southern Pesticides Corpn Ltd.

C. Endosulfan

Endosulfan is a pesticide belonging to the organochlorine group of pesticides, under the cyclodiene subgroup. This colourless solid is known for its acute toxicity. It is used against a broad spectrum of insects and mites in agriculture and allied sectors.

Uses

Endosulfan is one of the most effective broad-spectrum insecticides. It is used in vegetables, fruits, paddy, cotton, cashew, tea, coffee, tobacco and timber crops. It is also used as a wood preservative and to control tse-tse flies and termites. It is safe to use on parasites and predators and does not leave persistent residues in the environment – soil, plants and water. The technical grade active ingredient can be processed into various formulations i.e. E.C., dust, granules, flowables, WDP, etc. to control a wide range of sucking and chewing insects and acarine/ mite pests that attack crops.

Preparation of Endosulfan

Endosulfan is produced from hexachlorocyclopentadiene, by Diels-Alder reaction with butenediol, followed by cyclisation with thionyl chloride.

Major Producers of Endosulfan

The manufacturers of endosulfan in India are namely Excel Crop Care Ltd, Hindustan Insecticides Ltd, Coromandel International Ltd, Super Crop Safe Ltd and Aimco Pesticides Ltd.

D. Triazophos

Triazophos is a broad spectrum insecticide and acaricide with some nematicidal properties.

Uses

Triazophos primarily controls sucking and chewing insects in cotton, rice, oil seeds and vegetables, fruits and plantation, like tea, coffee and cardamom. In spite of being non-systemic, Triazophos can penetrate deeply in the plant tissues due to its translaminar properties and can effectively control leaf miner.

Preparation of Triazophos

The manufacturing process of Triazophos mainly includes four units: synthesis, extraction, isolation and recycle. Triazophos is made in the synthesis unit, and separated from other byproducts in the extraction and isolation units. In the recycle unit most of the solvent is recycled.

Major Producers of Triazophos

Nagarjuna Fertilizers and Chemicals Ltd is among the few firms that produces Triazophos in India.

E. Monocrotophos

Monocrotophos, an organophosphorus compound, is a broad spectrum, systemic insecticide and acaricide that is highly toxic in nature.

Uses

Monocrotophos effectively controls sucking, chewing and boring insects, and spider mites on cereals, cotton, soybean, sugarcane, ornamentals & tobacco. Besides, it is used on citrus, olives, rice, maize, sorghum, sugar beet, peanuts, potatoes and vegetables.

Preparation of Monocrotophos

The manufacturing of Monocrotophos is done by chlorination of Monomethyl acetoacetamide (MMAA) followed by condensation of the chlorinated product (MMACl) with Trimethyl phosphite (TMP) to form Monocrotophos Technical.

Major Producers of Monocrotophos

Firms producing Monocrotophos in India include Hindustan Insecticides Ltd, Nagarjuna Agrichem Ltd and Vantech Chemicals Ltd.

F. DDVP

Dichlorvos, also called as DDVP is an organophosphate compound. It is a dense colorless liquid with a sweetish smell and is highly soluble in water.

Uses

Dichlorvos used in pest control is diluted with other chemicals and used as a spray. Dichlorvos is used for insect control in food storage areas, green houses, and barns, and control of insects on livestock. Details of its uses are given below:
• In agriculture and horticulture: it is used in mushroom houses against mushroom flies; against various insects and beetles in poultry houses; on protected ornamentals, protected vegetables, herbs and brassica seedlings
• As a veterinary medicine, in protecting farmed salmon against salmon lice; and as an aerosol against cat and dog fleas
• In public hygiene as an aerosol insecticide and space spray
• It also has wide uses as an insecticide on vegetables, deciduous fruits, rice and plantation crops such as cotton, coffee, tea, cacao, banana, tobacco and spices.

Preparation of DDVP

Dichlorvos can be manufactured by the dehydrochlorination of trichlorphon (chlorophos) through the action of caustic alkalis in aqueous solution at 40 - 50 °C. The yield of dichlorvos in this process does not exceed 60%. Another process of manufacturing is where Tri-Methyl Phosphite (TMP) is slowly allowed to react chemically with tri chloro acetaldehyde at controlled conditions of temperature and at ambient pressure to produce crude DDVP.

Major Producers of DDVP

Firms producing DDVP in India include Gujarat Agrochem Ltd, Hindustan Insecticides Ltd and Super Crop Safe Ltd.

G. Cypermethrin

Cypermethrin is a synthetic pyrethroid insecticide. It is toxic and adequately stabile in air and light. It has become one of the most important insecticides in a wide-scale use. Most synthetic pyrethroids are complex molecules and cypermethrin is no exception. Cypermethrin is a mixture of all eight isomers.

Uses

Cypermethrin is used to control many pests, including moth pests of cotton, fruit, and vegetable crops. It is also used for crack, crevice, and spot treatment to control insect pests in stores, warehouses, industrial buildings, houses, apartment buildings, greenhouses, laboratories etc and also in food processing plants.

Preparation of Cypermethrin

Cypermethric Acid Chloride (CMAC) and Meta Phenoxy Benzaldehyde (MPBAD) are taken in an agitator reactor, in a solvent (Hexane). Sodium cyanide and water are added to the mass. Mass is agitated in reactor for the required time. At the end of reaction, the reaction mass is separated into two phases, organic layer and aqueous layer. Organic layer containing the product, Cypermethric technical with solvent is taken for distillation, where the solvent is removed and recycled. The final traces of solvent, which are around 3-4%, are removed under vacuum and recycled back.

Major Producers of Cypermethrin

Firms producing Cypermethrin include Aimco Pesticides Ltd, Gujarat Agrochem Ltd, Super Crop Safe Ltd and Pyrapure Chemicals Ltd.

H. Acephate

Acephate is an organophosphate foliar spray insecticide of moderate persistence with residual systemic activity of about 10-15 days at the recommended use rate and is considered non-phytotoxic on many crop plants. Acephate comes in the form of a soluble powder, pressurised spray or granular formulations and the substance decomposes on heating producing toxic fumes including nitrogen oxides, phosphorous oxides and sulfur oxides.

Uses

It is used for control of a wide range of biting and sucking insects, especially aphids, including resistant species, in fruit, vegetables (e.g. potatoes and sugar beets), vine, and in horticulture (e.g. on roses and chrysanthemums grown outdoors). It also controls leaf miners, lepidopterous larvae, sawflies and thrips in the previously stated crops as well as turf, mint and forestry.

Preparation of Acephate

The manufacturing process starts with the addition of Dimethyl Sulphate to Dimethyl thio phosphoramide (DMPAT) to give Methamodophos, which is acetylated with acetic Anhydride in presence of sulphuric acid to give crude acephate. Crude acephate is neutralised with ammonia solution and extracted in methylene chloride. The extracted acephate liquor is crystallised under chilled condition in presence of Ethyl acetate. Crystallised Acephate is then centrifuged and dried.

Major Producers of Acephate

Firms producing acephate in India include Rotam India Ltd, Super Crop Safe Ltd and Vantech Industry Ltd.

I. Chlorpyriphos

Chlorpyrifos belongs to a class of insecticides known as organophosphates and is one of the most-widely used active ingredients for pest control products in the world.

Uses

It is used to protect a number of important agricultural crops, such as corn, citrus, alfalfa, peanuts, and others cotton, mushrooms figs, bananas), nuts, vines, vegetables etc from pest insect attack. The most often quoted reason for the importance of chlorpyrifos in crop protection uses is the particular suitability of chlorpyrifos to integrated pest management (IPM) in having a relatively less harmful effect on beneficial insects and its use as a rotational tool in resistance management programs associated with these crops.

Preparation of Chlorpyriphos
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Major Producers of Chlorpyriphos

The firms producing Chlorpyriphos in India include Excel Crop Care Ltd, Aimco Perticides Ltd and Bhagiradha Chemicals & Industries Ltd.

J. Phorate

Phorate is an organophosphorus insecticide and acaricide and that is particularly effective against insects, mites, and nematodes and is very toxic.

Uses

Phorate is used to control sucking and chewing insects, leafhoppers, leafminers, mites, nematodes and rootworms. Phorate is used in pine forests and on roots and field crops, including corn, cotton, coffee, ornamental, herbaceous plants, and bulbs.

Preparation of Phorate

Phosphorus pentasulfide and ethyl alcohol are reacted slowly in the presence of Diethyl thio phosphoric acid (DETA) heel at 60-65⁰C. Hydrogen sulphide evolves from the reaction mixture. The gas is scrubbed with caustic lye. It gets converted to Di- sodium sulphide and sodium hydrogen sulphide, which has a by-product value. After the completion of reaction, the product is charged in another reactor through a sparkler filter. The product is reacted with formaldehyde and ethyl mercaptan at room temperature to produce crude phorate. This is a condensation reaction. Crude Phorate thus obtained is washed using washing soda and steam stripped to remove volatile organics and moisture.

Major Producers of Phorate

Firms producing phorate in India include Vimal Crop Care Pvt Ltd, Super Crop Safe Ltd and Vantech Chemicals Ltd.

K. Mancozeb

Mancozeb is a member of the ethylene bisdithiocarbamate (EBDC) group of fungicides, which includes the related active ingredients maneb and metiram. This compound has negligible vapor pressure, therefore it has a low potential to volatilize into the air. Mancozeb has low solubility in water and moderate absorption capacity in soil.

Uses

Mancozeb is used in agriculture, professional turf management, and horticulture. Mancozeb is used on a wide variety of food/feed crops, including tree fruits, vegetable crops, field crops, and grapes, ornamental plants.

Preparation of Mancozeb

Mancozeb is manufactured from carbon disulfide, ethylene diamine, manganese and zinc salts.

Manufacturing process consists of the following steps:
• Naham is produced by reacting ethylene diamine and carbon disulphide with sodiumhydroxide.
• Naham is reacted with manganese sulphate to produce Maneb.
• Maneb slurry is reacted with zinc sulphate to form mancozeb.
• Mancozeb slurry is dried in a spray drier to get technical grade mancozeb.

Major Producers of Mancozeb

Hindustan Insecticides Ltd and Rallis India are among the firms producing mancozeb in India.