Incompatibilities
Incompatible with oxidizers (chlorates,
nitrates, peroxides, permanganates, perchlorates, chlorine,
bromine, fluorine, etc.); contact may cause fires or explo-
sions. Keep away from alkaline materials, strong bases,
strong acids, oxoacids, epoxides.
Environmental Fate
Biological. In the presence of suspended natural populations from unpolluted aquatic
systems, the second-order microbial transformation rate constant determined in the laboratory was reported to be 5 × 10–10 L/organisms-hour (Steen, 1991).
Soil. Propanil degrades in soil forming 3,4-dichloroaniline (Bartha, 1968; Bartha and
Pramer, 1970; Chisaka and Kearney, 1970; Bartha, 1971; Duke et al., 1991; Pothuluri et
al., 1991) which is further degraded by microbial peroxidases to 3,3′,4,4′-tetrachloroazobenzene (Bartha and Pramer, 1967; Bartha et al., 1968; Chisaka and Kearney, 1970),
3,3′,4,4′-tetrachloroazooxybenzene (Bartha and Pramer, 1970), 4-(3,4-dichloroanilo)-
3,3′,4,4′-tetrachloroazobenzene (Linke and Bartha, 1970) and 1,3-bis(3,4-dichlorophenyl)triazine (Plimmer et al., 1970a), propanoic acid, carbon dioxide and unidentified
products (Chisaka and Kearney, 1970). Evidence suggests that 3,3′,4,4′-tetrachloroazobenzene reacted with 3,4-dichloroaniline forming a new reaction product, namely 4-(3,4-
dichloroanilo)-3,3′,4′-trichloroazobenzene (Chisaka and Kearney, 1970). Under aerobic
conditions, propanil in a biologically active, organic-rich pond sediment underwent dechlorination at the para- position forming N-(3-chlorophenyl)propanamide (Stepp et al., 1985).
Residual activity in soil is limited to approximately 3–4 months (Hartley and Kidd, 1987).
Plant. In rice plants, propanil is rapidly hydrolyzed via an aryl acylamidase enzyme
isolated by Frear and Still (1968) forming the nonphototoxic compounds (Ashton and
Monaco, 1991) 3,4-dichloroaniline, propionic acid (Matsunaka, 1969; Menn and Still,
1977; Hatzios, 1991) and a 3′,4′-dichloroaniline-lignin complex. This complex was identified as a metabolite of N-(3,4-dichlorophenyl)glucosylamine, a 3,4-dichloroaniline saccharide conjugate and a 3,4-dichloroaniline sugar derivative (Yi et al., 1968). In a rice
field soil under anaerobic conditions, however, propanil underwent amide hydrolysis and
dechlorination at the para position forming 3,4-dichloroaniline and m-chloroaniline (Pettigrew et al., 1985). In addition, propanil may degrade indirectly via an initial oxidation
step resulting in the formation of 3,4-dichlorolacetanilide which is further hydrolyzed to
3,4-dichloroaniline and lactic acid (Hatzios, 1991). In an earlier study, four metabolites
were identified in rice plants, two of which were positively identified as 3,4-dichloroaniline
and N-(3,4-dichlorophenyl)glucosylamine (Still, 1968).
Photolytic. Photoproducts reported from the sunlight irradiation of propanil (200 mg/L)
in distilled water were 3′-hydroxy-4′-chloropropionanilide, 3′-chloro-4′-hydroxypropionanilide, 3′,4′-dihydroxypropionanilide, 3′-chloropropionanilide, 4′-chloropropionanilide,
propionanilide, 3,4-dichloroaniline, 3-chloroaniline, propionic acid, propionamide,
3,3′,4,4′-tetrachloroazobenzene and a dark polymeric humic substance. The photolysis
products resulted from the reductive dechlorination, replacement of chlorine substituents
by hydroxyl groups, formation of propionamide, hydrolysis of the amide group and
azobenzene formation (Moilanen and Crosby, 1972). Tanaka et al. (1985) studied the
photolysis of propanil (100 mg/L) in aqueous solution using UV light (λ = 300 nm) or
sunlight. After 26 days of exposure to sunlight, propanil degraded forming a trichlorinated
biphenyl product (<1% yield) and hydrogen chloride (Tanaka et al., 1985).
Chemical/Physical. Hydrolyzes in acidic and alkaline media to propionic acid (Worthing and Hance, 1991) and 3,4-dichloroaniline (Sittig, 1985; Worthing and Hance, 1991).
The half-life of propanil in a 0.50 N sodium hydroxide solution at 20°C was determined
to be 6.6 days (El-Dib and Aly, 1976).
