Mario C.F Block C

Chemical Structure of Captan:


Molecular formula: C9H8Cl3NO2S

Molar Mass: 300.59 g mol−1

Density: 1.74 g/cm

Melting Point(solid): 178 °C (dec.)

IUPAC Name: (3aR,7aS)-2-[(trichloromethyl)sulfanyl]-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione

Brief Intro to Captan & Synopsis on Preparation

Captan(Fig. 1) is a general use pesticide categorized in the Phthalimide class of fungicides. Some Common uses for Captan

include adding it as a component of other pesticide mixtures,and using it for the control of many diseases on most fruits and

vegetables as well as ornamental plants. This generally improves the outward appearance of many fruits and vegetables, making

them appear brighter and healthier. Captan is useful for both home and agricultural use, its major use is commonly during apple

production; fifty percent of all the apple acreage in the U.S. are treated with captan as is sixty percent of the almonds and one

hundred percent of the Florida strawberries. One million tons of apples receive captan after harvest. Captan is generally applied to


packing and shipping boxes for fruits and vegetables to prevent diseases. Some other uses for

captan include being used as a preservative for awnings, draperies and leather, as a root dip

and seed treatment and is incorporated into paints, wallpaper pastes, plastic and leather

goods. There are 320 federally registered products that contain Captan. The EPA had cited

Captan as a probable carcinogen, but it was proven to be "not likely" to be a carcinogen

because of the exposure levels associated with agricultural usage. The usage of Captan on

crops has been canceled in the U.S. since 1989.Maleic_anhydride.png

Captan is a synthetic chloroalkyl thio fungicide introduced in 1949 by the Standard oil

Development company and later by the Chevron chemical company, approximately 13,000

tonnes of it was produced worldwide in 1983. Captan is Generally produced by reacting a

tetrahydro phthalimide(Fig. 2) which has been synthesized from maleic anhydride(Fig. 3) butadiene(Fig. 4) and ammonia(Fig. 5), with

Butadiene.pngperchloromethyl(Fig. 6) mercaptan(Fig.7). Since Tetrahydrophthamilide is generally produced by synthesizing

maleic anhydride butadiene and ammonia,Perchloromethyl Mercaptan on the other hand is formed by

chloronating disulfide in the presence of smallAmmonia_Structure.png quantities of iodine used as a

catalyst (0.005% - 2% usually depending on weight). The process of chloronating

carbon disulfide usually consumes 406g of carbon disulfide and 1.145 g of

chlorine per kilogram produced,of perchloromethyl mercaptan corresponding to a molar ratio Cl2/CS2

equal to 3.0. Captan usually forms as a white crystal it melts/decomposes at 178 degrees celciusPerchloro_methyl.gif, when

it decomposes it produces toxic fumes like sulfur oxides, nitrogen oxides,

hydrogen chloride, and phosgene. Thesefumes could have adverse effects on the

environment, special attention should be given to aquatic organisms and soil



Effects of Captan on Living Organisms

Several studies conducted on different animal species have shown that Captan is absorbed from the GI tract and is

rapidly metabolized. Whats left is excreted primarily in the urine. Rats who have been fed Captan excreted a third in the feces and

half in the urine in 24 hours. In another study rats exhaled fifteen to thirty percent in 45 hours. In 96 hours a total of ten to thirty

percent had been excreted in the feces and about fifty in the urine. Only one percent remained in the animal's tissues. Another

study was done on a cow it was also fed Captan in small amounts for four days, its milk had zero Captan in it at a 0.01 ppm detection

limit, there was also no Captan found it its urine using a 0.1 ppm detection limit. Rabbits injected with 500 mg/kg showed no Captan

in its blood over a 56 hour period. There is strong evidence that Captan causes cancer in female mice and in male rats. In addition,

Captan is chemically similar to two other pesticides that have been shown to produce cancer in test animals. Tumors were

associated with the gastrointestinal tract and, to a lesser degree, with the kidneys. Tests were done on pregnant mice, they were

expose by inhalation to high doses of Captan for four hours a day during days 6-15 of gestation, these mice showed significant

mortality, weight loss and fetal mortality followed. Mice that were fed 50 mg/kg over three generations reproduced normally. Fertility

and litter size was normal as was the growth of the young. The possibility of Captan causing reproductive effects on humans is

unlikely at low levels of exposure.

Diseases controlled by Captan

Captan controls a wide range of diseases on plants, fruits and vegetables including apple scab, fruit spot , sooty blotch

fly-neck,frog-eye, fruit rots, rust, alternaria leaf spots, botrytis flower blight, black spot on roses, and on lawns and turf brown patch,

external image scab.jpgleaf spot and root rot. Positive effects that Captan has on apples are that it helps prevent

scab(Fig. 8), fruit spot and bitter rot. On apricots it prevents brown rot and jacket rot. on

cherries it helps prevent leaf spot, brown rot(Fig. 9) and botrytis rot. On nectarines one

tablespoon of Captan in one gallon of water can help prevent scab and brown rot. On peaches

with 2.2 tablespoons in 1 gallon of water helps prevent brown rot and scab. Different doses of

Captan help control and eliminate certain diseases on household and agriculture plants, fruits

and vegetables.

external image brown-rot-on-cherry-fungus.JPG