Thiodicarb

Description

Thiodicarb, 3,7,9,13-tetramethyl-5,11- dioxa-2,8,14-trithia-4,7,9,12-tetra-azapentadeca-3,12-di ene-6,10-dione (IUPAC), consists of colorless crystals, which are sparingly soluble in water, readily soluble in dichloromethane, acetone, methanol, and xylene. Thiodicarb is produced by reaction of N,N -thiobis(methylcarbamic acid fluoride) with 2-methylthioacetaldoxim in the presence of a base.

The Uses of Thiodicarb

Thiodicarb is used as an insecticide.

The Uses of Thiodicarb

Thiodicarb is an oxime carbamate insecticide and ovicide with both oral and contact activities against major Lepidoptera, Coleoptera, Diptera and Hemiptera pests in/on cotton, maize, fruits, soyabeans and vegetables.

General Description

Colorless to pale tan crystals. Non corrosive. Used as an insecticide.

Air & Water Reactions

Hydrolyzed by strong acid or base.

Reactivity Profile

A carbamate derivative. Carbamates are chemically similar to, but more reactive than amides. Like amides they form polymers such as polyurethane resins. Carbamates are incompatible with strong acids and bases, and especially incompatible with strong reducing agents such as hydrides. Flammable gaseous hydrogen is produced by the combination of active metals or nitrides with carbamates. Strongly oxidizing acids, peroxides, and hydroperoxides are incompatible with carbamates.

Agricultural Uses

Insecticide, Molluscicide, Ovicide: Not approved for use in EU countries. Registered for use in the U.S. Thiodicarb is used primarily on cotton, sweet corn, and soybeans. The remaining usage is spread among leafy vegetables, cole crops, ornamentals, and other minor use sites. Thiodicarb acts as an ovicide against cotton bollworms and budworms.

Trade name

CGA® 45156; CHIPCO[C]; DICARBOSULF®; DICARBASULF®; LARVIN®; LEPICRON®; SEMEVIN®; NIVRAL®; UC-51762®; UC 51769®; UC 80502®

Environmental Fate

Soil. Under aerobic and anaerobic soil conditions, thiodicarb degrades to methomyl and methomyl oxime (Hartley and Kidd, 1987). The reported half-life in various soils is 3–8 days (Hartley and Kidd, 1987).

Metabolic pathway

The initial metabolic reaction of thiodicarb in soils, plants and animals is the hydrolytic or thiolytic cleavage of the N-S bond to methomyl. The subsequent metabolic pathway of methomyl involves hydrolysis / elimination reactions to yield S-methyl-N-hydroxythioacetimidate and ultimately acetonitrile and CO₂ as the major terminal products. The metabolic pathways of thiodicarb are presented in Scheme l. See also the methomyl entry.

Degradation

Thiodicarb (1) is susceptible to alkaline hydrolysis (Feung and Heinzelmann, 1989). Thiodicarb was stable between pH 5 and 6, but it degraded rapidly in alkaline conditions (pH 9) with a DT₅₀ of less than one day. The DT₅₀ values of thiodicarb at pH 3 and 7 were 9 and 13 days, respectively. The initial degradation product of thiodicarb was methomyl (2) which was further hydrolysed to S-methyl-N-hydroxytoacetimidate (3) in alkaline solution (pH 9).
Photolysis of thiodicarb in water was not significant (Andrawes and College, 1977). The photolytic DT₅₀ of thiodicarb was approximately 81 days. The major photolytic degradation product was methomyl(2).