tetrachloroisophthalonitrile

 2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile

C₈Cl₄N₂

Colourless, odourless crystals; (tech. has a slightly pungent odour). 

252.1^oC

350^oC/760 mmHg

0.076 mPa (25^oC)

2.0 (20^oC) 

In water 0.81 mg/l (25^oC). In xylene 80, cyclohexanone, dimethylformamide 30, acetone, dimethyl sulfoxide 20, kerosene <10 (all in g/kg, 25^oC).

Thermally stable at ambient temperatures. Stable to u.v. light in aqueous media and in crystalline state. Stable in acidic and moderately alkaline aqueous solutions; slow hydrolysis at pH >9. 

2.50×10-² Pa m³ mol^-1 (25^oC)

2.92 (25^o

Conjugation with, and depletion of, thiols (particularly glutathione) from germinating fungal cells, leading to disruption of glycolysis and energy production, fungistasis and fungicidal action.

Non-systemic foliar fungicide with protective action.

Control of many fungal diseases in a wide range of crops, including pome fruit, stone fruit, citrus fruit, bush and cane fruit, cranberries, strawberries, pawpaws, bananas, mangoes, coconut palms, oil palms, rubber, pepper, vines, hops, vegetables, cucurbits, tobacco, coffee, tea, rice, soya beans, peanuts, potatoes, sugar beet, cotton, maize, ornamentals, mushrooms, and turf. Application rates for food crops are 1-2.5 kg/ha.

Russetting is possible with flowering ornamentals, apples, and grapes. Some varieties of flowering ornamentals may be injured. Pittosporum foliage is sensitive. Phytotoxicity may be increased with oils or oil-containing substances. 

Not compatible with oils. 

CAG

Acute oral LD₅₀ for rats >5000 mg/kg.

Acute percutaneous LD₅₀ for albino rabbits >5000 mg/kg. Severe eye irritant; mild skin irritant (rabbits). Evidence in humans of contact dermatitis with repeated exposure.

LC₅₀ (1 h) for rats 0.52 mg/l air; (4 h) for rats 0.10 mg/l air

Chronic administration of chlorothalonil has been associated with renal hyperplasia and hyperkeratosis of the forestomach in the kidney and forestomach of rats and male mice. These pre-neoplastic lesions precede subsequent tumour development in the rodent kidney and forestomach. The mode of action has been demonstrated to be epigenetic with a NOEL of 1.8 in rats and 1.6 in mice. In dogs, the pattern of toxicity is different from that in rodents with no evidence of toxicity in the kidney or forestomach, and a NOEL of at least 3 mg/kg b.w. (JMPR 1994).

(JMPR) 0.03 mg/kg [1994]; (EPA) 0.02 mg/kg (RED 1998)

WHO (a.i.) U; EPA (formulation) II ('Bravo' SC)

R40| N; R50, R53 

Acute oral LD₅₀ for mallard ducks >4640 mg/kg. Dietary LC₅₀ (8 d) for mallard ducks and bobwhite quail >10 000 mg/kg diet. 

LC₅₀ (96 h) for rainbow trout 47, bluegill sunfish 59, channel catfish 43 mg/l. 

LC₅₀ (48 h) 70 ug/l.

EC₅₀ (120 h) for Selenastrum capricornutum 210 ug/l; EC₅₀ (72 h) for Navicula pelliculosa 5.1 ug/l.

LC₅₀ (14 d) >404 mg/kg

In plants the majority of residues remain as parent compound; 4-hydroxy-2,5,6-trichloroisophthalonitrile is found as a metabolite to a limited extent. 

Chlorothalonil is not well absorbed following oral dosing. It reacts with glutathione in the gut rumen, or immediately on absorption into the body, to give mono-, di- or tri- glutathione conjugates. These may be excreted through urine or faeces, or subject to further metabolism resulting in thiol or mercapturic acid derivatives. Excretion of these in urine is believed to be significantly greater in rats than in dogs or primates. In ruminants, the major identified metabolite is the the 4-hydroxy derivative; no parent material is found. 

Koc 1600 (sand) to 14 000 (silt), indicating low mobility to immobile. In aerobic and anaerobic soil studies, DT₅₀ is 0.3-28 d (20^oC). Stable to hydrolysis at pH 5-7, at pH 9 (22^oC), DT₅₀ is 38 d. Degradation is faster in biotic aquatic systems, typical DT₅₀ (aerobic) <8 h, (anaerobic) <10 d. A wide variety of metabolites are formed which are in turn degraded further.. 

Product analysis by glc