THALLIUM(I) SULFATE

Chemical Properties

white fine crystalline powder or needles

Uses

Thallium(I) sulfate is used as a precursor to thallium(I) sulfide, which exhibits high electrical conductivity when exposed to infrared light. It is further used in photocells. It is also mixed with selenium and arsenic to produce low melting glasses.

Uses

As rat poison, as ant bait and as a reagent in analytical chemistry.

Definition

ChEBI: Thallium sulfate is a metal sulfate in which the counterion is thallium and the ratio of thallium to sulfate is 2:1. It is a rodenticide used to control rats, squirrels, mice, moles, prairie dogs, ants and cockroaches. It is no longer registered for pesticide use in the United States. It has a role as a rodenticide and an insecticide. It is a thallium molecular entity and a metal sulfate. It contains a thallium(1+) and a sulfate.

Production Methods

Commercial sources are flue dusts, either from pyrite (FeS2) burners or from lead and zinc smelters and refiners, as a byproduct of cadmium production at the rate of a few thousand pounds per year. In the flue dusts thallium occurs largely as a sulfate, which is extracted with hot water or dilute sulfuric acid. The purification of thallium is accomplished by taking advantage of the difference in solubility of certain thallium compounds and the impurities. Traces of zinc, copper, cadmium, lead, and indium are removed by dissolving the thallium in and precipitating the impurities with hydrogen sulfide.

General Description

Odorless white rhomboid prisms or a dense white powder. Density 6.77 g / cm3. Melting point 1170°F (632°C). Extremely toxic by ingestion. Very toxic by skin absorption and ingestion. A slow acting cumulative poison. Used as a rat poison, and an ant bait. Also used for analysis (testing for iodine in the presence of chlorine) and ozonometry. Not registered as a pesticide in the U.S.

Air & Water Reactions

Soluble in water.

Reactivity Profile

THALLIUM(I) SULFATE has weak oxidizing and weak reducing powers. Redox reactions can however still occur.

Health Hazard

Rated as extremely toxic. The probable oral lethal dose in humans is 5 to 50 mg/kg, or between 7 drops and 1 teaspoon for a 150-pound person. The mean lethal dose in an adult is probably about 1 gm of THALLIUM(I) SULFATE. Chronic exposure causes hair loss starting 10 days after exposure and complete baldness in about a month.

Fire Hazard

When heated to decomposition, THALLIUM(I) SULFATE emits very toxic fumes of thallium and sulfur oxide.

Mechanism of action

Disrupts essential cellular processes including pyruvate kinase and succinate dehydrogenase

Safety Profile

Human poison by ingestion. Experimental poison by ingestion and subcutaneous routes. Human systemic effects by ingestion: ataxia, change in heart rate, excitement, eye changes, irritability, nausea or vomiting, nerve or sheath structural changes, somnolence, wakefulness. Experimental reproductive effects. When heated to decomposition it emits very toxic fumes of T1 and SOx. Used as a rat poison, ant bait, and a reagent in analytical chemistry. See also THALLIUM COMPOUNDS and SULFATES.

Carcinogenicity

Thallium is not classifiable with respect to carcinogenicity due to a lack of relevant human and animal studies. Several subchronic and chronic animal studies on thallium and compounds are available; however, they were not designed to examine carcinogenic end points.

Purification Methods

The sulfate crystallises from hot water (7mL/g) by cooling; then dry it under vacuum over P2O5. It is POISONOUS.

Pesticide Type

Rodenticide; Insecticide