Profenofos

1.Chemical and physical Properties

1.1 Chemical Identity

• Common Name: Profenofos
• Chemical Name (IUPAC): O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate
• CAS Registry Number: 41198-08-7
• Chemical Class: Organophosphate insecticide/acaricide
• Molecular Formula: C₁₁H₁₅BrClO₃PS
• Molecular Weight: 373.63 g/mol

1.2 Key Physical Properties

• Appearance: Pale yellow to amber-colored oily liquid. Technical grade is often brownish.
• Odour: Garlic-like or mercaptan-like odour.
• Melting Point: Not applicable (liquid at room temperature).
• Boiling Point: Approximately 100°C at 1.8 Pa (0.0135 mmHg); Decomposes at higher temperatures (e.g., >150-200°C).
• Vapour Pressure: Relatively low but higher than many other organophosphates (e.g., 0.124 mPa or 1.24 x 10⁻⁶ hPa at 20°C; or 9.3 x 10⁻⁷ mmHg at 20°C). This indicates some potential for volatilization.
• Density: Approximately 1.455 g/cm³ at 20°C.
• Solubility:
  • Water: Low solubility; 28 mg/L (28 ppm) at 25°C.
  • Organic Solvents: Readily miscible with most organic solvents, such as acetone, dichloromethane, ethanol, methanol, toluene, xylene, n-hexane.
• Log K_ow (Octanol-Water Partition Coefficient): Typically around 4.0 - 4.8, indicating high lipophilicity and potential for bioaccumulation, though this may be offset by metabolism and degradation

1.3 Key Chemical Properties

• Stability:
  • Relatively stable in neutral and weakly acidic media.
  • Hydrolyzes in alkaline media; hydrolysis rate increases with pH and temperature.
  • Susceptible to photodegradation, but generally more stable than some other organophosphates.
• Corrosivity: Can be corrosive to some metals.

2.Production Technologies

2.1 Synthesis Overview

1. Synthesis of 4-bromo-2-chlorophenol: This key intermediate can be prepared from 2-chlorophenol by bromination or from p-bromophenol by chlorination.
2. Phosphorylation: Reacting 4-bromo-2-chlorophenol with O-ethyl S-propyl phosphorochloridothioate (or O-ethyl phosphorodichloridothioate followed by reaction with propanethiol and then 4-bromo-2-chlorophenol, or similar variations).
   1. The O-ethyl S-propyl phosphorochloridothioate can be synthesized from thiophosphoryl chloride (PSCl₃) by sequential reactions with ethanol and then propanethiol (or sodium propanethiolate), or vice versa.

2.2 Key Raw Materials

• 2-Chlorophenol or p-Bromophenol (or other precursors for 4-bromo-2-chlorophenol)
• Brominating agents (e.g., bromine)
• Chlorinating agents (e.g., chlorine, sulfuryl chloride)
• Thiophosphoryl chloride (PSCl₃)
• Ethanol
• n-Propanethiol (n-propyl mercaptan)
• Bases (e.g., sodium hydroxide, triethylamine)
• Solvents

2.3 Formulation

• Emulsifiable Concentrates (EC): Most common formulation.
• Ultra-Low Volume (ULV) liquids
• May also be found in mixtures with other insecticides (e.g., pyrethroids) to broaden the spectrum of control or manage resistance.

3.Applications

3.1 Mode of Action

• Profenofos is a non-systemic insecticide and acaricide with contact and stomach action. It also exhibits translaminar activity (penetrates leaf tissues to form a reservoir of active ingredient within the leaf).
• Like other organophosphates, it acts as an acetylcholinesterase (AChE) inhibitor.
• Mechanism: It (or its active metabolite, if bioactivated) phosphorylates the serine hydroxyl group in the active site of the AChE enzyme. This irreversible inhibition of AChE leads to the accumulation of the neurotransmitter acetylcholine (ACh) at nerve synapses. The continuous nerve stimulation results in hyperexcitation, convulsions, paralysis, and ultimately the death of the insect or mite.
• Belongs to Group 1B of the Insecticide Resistance Action Committee (IRAC) classification.

3.2 Crops

• Cotton: A major historical market for controlling bollworms, aphids, spider mites, and whiteflies.
• Soybeans
• Corn (Maize)
• Potatoes
• Sugar beet
• Vegetables: Including tomatoes, cole crops, beans.
• Tobacco
• Ornamentals

3.3 Pests Controlled

• Lepidopteran Pests (Caterpillars): Bollworms (e.g., Helicoverpa armigera, Heliothis virescens), armyworms, cutworms, leafrollers, budworms.
• Sucking Insects: Aphids, whiteflies (especially Bemisia tabaci), jassids (leafhoppers), thrips.
• Mites: Spider mites (e.g., Tetranychus spp.).
• Some Beetles: Colorado potato beetle.
• It is known for its good activity against resistant strains of some pests, particularly certain whitefly and mite populations, due to a somewhat different binding characteristic to AChE compared to some other OPs.

4.Market Analysis

4.1 Global Market Overview

• Profenofos was historically a significant insecticide, particularly for cotton pest control, especially in developing countries where broad-spectrum, cost-effective solutions were sought.
• Its market share has declined considerably in many regions due to:
  • High mammalian toxicity and associated risks to applicators.
  • Significant ecotoxicological concerns (especially for birds and aquatic life).
  • Regulatory restrictions and bans.
  • Development of insecticide resistance in some target pests.
  • Availability of newer, safer, and often more selective insecticides (e.g., pyrethroids, neonicotinoids (though these have their own issues), diamides).
• It may still be used in some countries where regulations are less stringent or for specific pest problems where alternatives are limited or less effective.

4.2 Key Market Dynamics

• Drivers (Historically):
  • Broad-spectrum activity.
  • Effectiveness against mites as well as insects.
  • Translaminar action.
  • Relatively low cost in some markets.
  • Effectiveness against some OP-resistant pests.
• Restraints/Challenges:
  • High Human Toxicity: Major concern for worker safety.
  • Severe Ecotoxicity: High risk to birds, fish, and bees.
  • Regulatory Bans and Restrictions: Phased out or heavily restricted in many countries (e.g., EU, USA (many uses cancelled or restricted), and others).
  • Insecticide Resistance: While it could control some resistant strains, resistance to profenofos itself has also developed in some pests.
  • Negative Public Perception: Due to its hazardous nature.
  • Shift towards IPM and safer alternatives.

5.Upstream and Downstream Linkages

5.1 Upstream Linkages(Inputs for Production)

• Basic Chemicals: Phenol derivatives, bromine, chlorine.
• Intermediates: 4-bromo-2-chlorophenol, thiophosphoryl chloride, ethanol, n-propanethiol.
• Sourcing of these raw materials from the chemical industry.

5.2 Downstream Linkages (outputs and consumers)

• Agrochemical Formulators: Purchase technical grade profenofos to produce EC formulations and mixtures.
• Distributors and Retailers: Supply formulated products to end-users.
• Farmers: Primarily cotton growers historically, and growers of other crops in regions where it is still permitted.
• Pest Control Operators (less common for this product compared to others).