Dichloromethyl(3,3,3-trifluoropropyl)silane

Endpoint summary

Description of key information

No studies are available. Based on molecular structure, molecular weight, water solubility, and octanol-water partition coefficient it can be expected that the submission substance is unlikely to be absorbed via the oral, dermal, and inhalation routes. However, dichloromethyl(3, 3, 3-trifluoropropyl)silane is a highly moisture-sensitive liquid that hydrolyses rapidly in contact with water (half-life 12 seconds at pH 7 and 20°C), generating hydrogen chloride (HCl) and methyl(3, 3, 3-trifluoropropyl)silanediol. Due to the corrosivity of HCl, penetration of the silanol-containing hydrolysis product is enhanced and systemic availability can be expected. Based on the high water solubility of the silanol-containing hydrolysis product, the amounts absorbed are likely to be distributed in the body, a fast excretion via the renal route can be expected, and the bioaccumulation potential is therefore expected to be low. Hydrogen and chloride ions will enter the body’s natural homeostatic processes.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Additional information

Toxicokinetic Behaviour Assessment for dichloromethyl(3, 3, 3-trifluoropropyl)silane (CAS No: 675-62-7):

There are no studies available in which the toxicokinetic properties of dichloromethyl(3, 3, 3-trifluoropropyl)silane have been investigated. Therefore, the toxicokinetic behaviour assessment of the substance and its hydrolysis product was assessed by its physico-chemical properties.

Dichloromethyl(3, 3, 3-trifluoropropyl)silane is a highly moisture-sensitive liquid that hydrolyses rapidly in contact with water (half-life <17 seconds at pH 7 and 1.5°C), generating hydrogen chloride (HCl) and methyl(3, 3, 3-trifluoropropyl)silanediol. The substance would also hydrolyse rapidly in contact with moist skin; the resulting HCl hydrolysis product would be severely irritating or corrosive.This therefore suggests that systemic exposure to the substance will be to the hydrolysis product rather than the parent substance. Therefore, this toxicokinetic behaviour assessment will try to predict the behaviour of the hydrolysis product methyl(3, 3, 3-trifluoropropyl)silanediol.

The molecular weight and predicted water solubility of the hydrolysis product methyl(3, 3, 3-trifluoropropyl)silanediol are 174.19 g/mol and 13500 mg/l, respectively. The moderate log Kow of 1.0, water solubility of 13500 mg/l and small molecular weight of the hydrolysis products suggest that it may have the potential to pass through biological membranes.

 

Absorption

Oral: If absorption occurs, the hydrolysis of the parent substance in the low pH of the stomach will be rapid (t1/2 of 8 seconds at pH 4), so absorption of the parent substance is expected to be minimal and it is more likely to be the hydrolysis product.

The predicted water solubility of 13500 mg/l of the hydrolysis product suggests that the hydrolysis product will readily dissolve into the gastrointestinal fluids. Also, the low molecular weight (less than 200) of the hydrolysis product suggests that it may have the potential to pass through aqueous pores or be carried through the epithelial barrier by the bulk passage of water. Furthermore, the moderate Log Kow of 1.0 of the hydrolysis product indicates it is favourable to be absorbed by passive diffusion. In an acute oral toxicity study two animals died at 2000 mg/kg bw (LPT 2002). Thus, systemic availability cannot be excluded.

Dermal: The moderate water solubility of 13500 mg/l, Log Kow of 1.0 and molecular weight of 174.16 g/mol of the hydrolysis product suggest that absorption will be minimal. QSAR based dermal permeability prediction (DERWIN V2.00.2009) using molecular weight, log Pow and water solubility, calculated a dermal penetration rate 0.00364 mg/cm²/h for methyl(3, 3, 3-trifuoropropyl)silanediol. This shows that dermal penetration of the hydrolysis product will be very low. Since the other hydrolysis product, HCl is corrosive to the skin; damage to the skin might increase penetration. There are no reliable studies available for dermal toxicity, as they are not required due to the corrosive properties of the test substance.

Inhalation: The predicted vapour pressure of the parent substance (740 Pa) indicates that inhalation as a vapour could occur. The moderate log Kow and water solubility of the hydrolysis product of 1.0 and 13500 mg/l, respectively, indicates the substance is favourable for absorption directly across the respiratory tract epithelium by passive diffusion. As with dermal exposure, damage to membranes caused by the corrosive nature of the HCl hydrolysis product might enhance the uptake. There are no reliable studies available for toxicity after inhalation, as they are not required due to the corrosive properties of the test substance.

Distribution

The small molecular weight (174.16 g/mol) and moderate water solubility of methyl(3, 3, 3-trifluoropropyl)silanediol suggest it will diffuse through aqueous channels and pores, also the log Kow of 1.0 indicates it is likely to be distributed into cells and therefore the intracellular concentration will be higher than the extracellular concentration. Hydrogen and chloride ions will enter the body’s natural homeostatic processes.

Metabolism

Dichloromethyl(3, 3, 3-trifluoropropyl)silane is a moisture-sensitive liquid that hydrolyses rapidly to form methyl(3, 3, 3-trifluoropropyl)silanediol and HCl. There are no data regarding the metabolism of methyl(3, 3, 3-trifluoropropyl)silanediol. Genetic toxicity test in vitro showed no observable differences in effects with and without metabolic activation for dichloromethyl(3, 3, 3-trifluoropropyl)silane.

Excretion

The low molecular weight (below 300) and good water solubility of the hydrolysis product suggest that they are likely to be excreted by the kidneys into urine.