Inorganic Insecticides

Inorganic insecticides are some of the oldest insecticides used in agriculture. However, these insecticides have been largely replaced by synthetic insecticides. Boric acid, borax, disodium octaborate tetrahydrate, and cryolite are still available on the market. 

Boric acid (H3B03) is used against cockroaches and other crawling house pests such as ants. It has long residual activity. Its oral LD50 in rats is 2500-5000 mg/kg. 

Sodium tetraborate decahydrate (borax) (Na2B407 10 H20) is a stomach poison used against all common household ants and cockroaches. Its oral LD50 in rats is 2660-5190 mg/kg. 

Disodium octaborate tetrahydrate (a borate salt) (Na2B8013 4 H20) is a larvicide used to treat lumber and other wood products to control termites and other wood-infesting insects. Its oral LD50in rats is 2.0 g/kg. 

Cryolite (Na3AlF6) is a naturally occurring mineral and is used as a stomach poison for fruit and vegetable insects. It is relatively nontoxic to mammals. 

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Sprays are the most common means of insecticide appHcation and generally involve the use of water as the principal carrier, although volatile oils sometimes are used. With the older inorganic insecticides, suspensions in water were used at dilutions of 0.1 ndash 0.2%. The development of the more effective organic insecticides has allowed the widespread use of concentrate sprays in which the toxicant is contained at 10 ndash 98% and the amount of carrier to be appHed is enormously reduced. The use of concentrate or ultralow volume sprays has brought about a revolution in spray equipment away... 

Lead hydrogen arsenate, an inorganic insecticide used against the potato beetle, is produced by the following reaction ... 

Noncatalytic Reactions Chemical kinetic methods are not as common for the quantitative analysis of analytes in noncatalytic reactions. Because they lack the enhancement of reaction rate obtained when using a catalyst, noncatalytic methods generally are not used for the determination of analytes at low concentrations. Noncatalytic methods for analyzing inorganic analytes are usually based on a com-plexation reaction. One example was outlined in Example 13.4, in which the concentration of aluminum in serum was determined by the initial rate of formation of its complex with 2-hydroxy-1-naphthaldehyde p-methoxybenzoyl-hydrazone. ° The greatest number of noncatalytic methods, however, are for the quantitative analysis of organic analytes. For example, the insecticide methyl parathion has been determined by measuring its rate of hydrolysis in alkaline solutions. 

Many formerly common herbicides now have been banned or restricted in their use, e.g., 2,4-D and 2,4,5-T. However, the number and diversity of herbicides far exceeds that of insecticides. There are both organic and inorganic herbicides. Examples of inorganic herbicides are CUSO4 and NaC104. 

Z)-9-Tricosene [(Z)-CH3(CH2)7CH=CH(CH2)i2CH3] is the sex pheromone of the female housefly. Synthetic (Z)-9-tricosene is used as bait to lure male flies to traps that contain insecticide. Using acetylene and alcohols of your choice as starting materials, along with any necessary inorganic reagents, show how you could prepare (Z)-9-tricosene. 

In one procedure that has been widely used, the sample, after suitable treatment, is refluxed with sodium and isopropyl alcohol, after which the solution is diluted with water and the inorganic chloride is determined by standard methods (13, 54) The method has been adopted by the Association of Official Agricultural Chemists 29, 30) as a tentative one for technical DDT and for dusts, oil solutions, and aqueous emulsions of DDT, for use in the absence of other chlorine-containing compounds. The National Association of Insecticide and Disinfectant Manufacturers has also accepted the total-chlorine method for the analysis of these preparations 28). Essentially the same procedures have been described by Donovan 22), of the Insecticide Division of the Production and Marketing Administration, for technical DDT and various commercial DDT products containing no other compounds interfering with the chlorine determination. 

The use of plant extracts for insect control dates into antiquity the use of Paris green as an insecticide for control of the Colorado potato beetle in 1867 probably marks the beginning of the modern era of chemical control of injurious insects. The development of lead arsenate followed later in the nineteenth century for gypsy moth control. The commercial production of nicotine insecticides, the production of calcium arsenate at the time of the first world war, and the use of fluorine, arsenical, and cyanide compounds, as well as other inorganic chemicals for insect control, were important steps in pest control. These chemicals were applied largely by dilute high pressure sprays or dusts. 

Herbicides, insecticides, fungicides, nitrates, phosphates, potassium, BOD, nutrients, heavy metals, inorganic salts, pathogens, surfactants organic solvents used in cleaning... 

Our discussion of pesticides has focused primarily on insecticides. In the United States the primary use of pesticides is in the form of herbicides, those pesticides used to control weeds. Approximately 70% of the pesticides used in the United States are herbicides and 20% are insecticides. The use and development of herbicides parallels that of insecticides. The first herbicides were inorganic metal compounds and salts. During World War II organic herbicides were synthesized and their use increased dramatically. One of the first major classes of herbicides synthesized in the mid-1940s was phenoxyaliphatic acids. As this name implies, the phenoxyaliphatic acids contain the benzene ring, oxygen, and an aliphatic acid. The two most common phenoxyaliphatic acids are 2,4 dichlorophenoxyacetic acid, called 2,4-D and 2,4,5 trichlorophenoxyacetic acid, known as 2,4,5-T (Figure 18.10). The numbers in these... 

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