Report of the Pesticides research Project

Abstract

Economy of Pakistan depends on agriculture, but unfortunately the yield per acre of food and cash crops is considered to be among the lowest in the world. The loss caused by plant diseases, insects, pests, weeds and rodents is estimated to be about 30% of total harvest. At present Pakistan is placed at the bottom of the list of countries using pesticides. This because of the fact that import of these substances requires the expenditure of a large sum of money in terms of foreign exchange. Only two pesticides namely, DDT and BHC are being produced in the country and that too in limited quantity which is insufficient to meet our requirements. The fact that the per acre yield of the crop be increased by the use of pesticides can be seen from the following table which shows the relationship between crop yield and the amount of pesticides used in different countries. Country Pesticides (gm) Crop yield (kg) Japan 10,790 5480 Europe 1,870 3430 U.S.A 1,190 2600 India 149 820 The above figures prove the point that the yield of crop depends directly upon the use of pesticides. A large number of organic and inorganic compounds are being used as pesticides all over the world. It is well known that almost all the chlorinated hydrocarbons, more or less, possess pesticidal properties. These chemicals are of value not only as pesticide, insecticides, fungicides, herbicides but are also useful as solvents, intermediaries for several products of medicinal importance, paints etc. Most of the commercial pesticides available namely D.D.T, BHG, heptachlor, Aldrin, dieldrin and texaphene are chlorinated products of hydrocarbons like benzene, cyclopentadiene and certain fractions of terpentine oil. In the view of the importance of the pesticides for increasing the crop yield, it is desirable that our country should be Self Sufficient in these chemicals. We, therefore have tried to chlorinate the hydrocarbons. In fact, this is not the first attempt in this direction. Qureshi was the first to report the chlorination of petroleum hydrocarbons in this country. He used different low boiling petroleum cuts for chlorination under various experimental conditions later Siddiqui et al. reported the production of pesticides from petroleum hydrocarbons boiling in the range of 35-1550C. The chlorination was carried out in a vertical column to yield a partially chlorinated product with sp.gravity of 1.30-1.35 which was rechlorinated till the final product had a specific gravity of 1.40 to 1.45. The above procedure has the inherent, disadvantage that the reaction is completed in two stages, rate of chlorination is slow and requires mixing of the final product. Qureshi designed a chlorinator for chlorination of about 60 liters of petroleum cuts boiling range 35-155oC. The density rise to 1.425 when chlorination was stopped and the product allowed to settle down. The present work deals, the production of an insecticide/pesticide from hydrocarbons, under such a condition that danger of explosion and fire is obviated.