Overview
Propanil is a selective contact herbicide developed in the 1950s for use in rice cultivation. It belongs to the anilide chemical class and functions by inhibiting photosystem II in susceptible weed species. The compound demonstrates particular effectiveness against barnyard grass (Echinochloa crus-galli) while showing good crop safety for rice when properly applied. As one of the most extensively used rice herbicides globally, propanil accounts for significant market share in tropical rice-growing regions. Its popularity stems from reliable performance, relatively low mammalian toxicity compared to alternatives, and cost-effectiveness for large-scale agricultural operations.
Physical and Chemical Properties
Propanil appears as white to tan crystalline solid at room temperature with a characteristic faint aromatic odor. The compound demonstrates moderate stability under normal storage conditions but degrades when exposed to strong acids, bases, or ultraviolet light. Its vapor pressure is negligible (1.1×10-5 Pa at 25°C), reducing volatilization risks during application. The herbicide shows limited water solubility (20-25 mg/L at 20°C) but readily dissolves in many organic solvents including acetone, ethanol, and xylene. This property informs formulation development, with emulsifiable concentrates being the most common commercial form. Hydrolysis occurs at extreme pH levels, with half-lives of 1-3 days at pH 9 and several weeks at neutral pH.
Main Applications
Propanil serves primarily as a post-emergence herbicide in transplanted and direct-seeded rice fields, typically applied at 2-4 kg active ingredient per hectare. It controls annual grasses and broadleaf weeds including barnyard grass, sprangletop, and smartweed. Application timing proves critical - usually 2-5 leaf stage of weeds and 3-5 leaf stage of rice for optimal selectivity. In some regions, propanil sees use in combination with other herbicides (e.g., 2,4-D) to broaden the weed control spectrum. The compound occasionally finds application in non-crop areas, though this represents a minority usage. Its rapid degradation in soil (half-life 1-3 days) prevents carryover issues for subsequent crops in rotation systems.
Safety and Storage
Propanil carries moderate acute toxicity (EPA Toxicity Class III) with primary exposure risks being eye irritation and potential methemoglobinemia formation with significant ingestion. Proper personal protective equipment including gloves, goggles, and respirators should be worn during mixing and application. The compound shows low bioaccumulation potential but may prove toxic to aquatic organisms. Storage requires dry, well-ventilated areas away from food/feed and oxidizing agents. Bulk quantities should be kept in original containers with intact labels at temperatures below 30°C. Spill management involves containment with inert absorbent materials, avoiding water runoff that could contaminate waterways. Fire hazards are minimal but combustion may produce toxic nitrogen oxides and hydrogen chloride gas.
B2B Procurement Guide
When sourcing propanil, agricultural buyers should prioritize suppliers with certified Good Agricultural Practices (GAP) compliance. Technical grade material (95-98% purity) represents the most cost-effective option for formulation businesses, while end-users typically purchase ready-to-use emulsifiable concentrates (360-480 g/L active ingredient). Key procurement considerations include batch analysis certificates verifying active ingredient content and impurity profiles, proper packaging (usually 200L steel drums or IBC totes for bulk orders), and supply chain transparency. Market prices fluctuate with raw material (especially aniline) costs and regional demand patterns. Southeast Asian manufacturers often offer competitive pricing, but importers must confirm registration status in destination countries.