Fenamiphos Chemical Properties

Melting point:

49°C

Boiling point:

375.6±52.0 °C(Predicted)

Density 

1.14

vapor pressure 

1.2 x 10^-4 Pa (20 °C)

Flash point:

100 °C

storage temp. 

0-6°C

solubility 

Chloroform (Slightly), Methanol (Slightly)

pka

-0.09±0.70(Predicted)

form 

Liquid

color 

Brown

Water Solubility 

0.07 g/100 mL

Merck 

13,3984

BRN 

4752893

Exposure limits

OSHA PEL: TWA 0.1 mg/m3; ACGIH TLV: TWA 0.1 mg/m3.

LogP

4.01 at 30℃

CAS DataBase Reference

22224-92-6(CAS DataBase Reference)

NIST Chemistry Reference

Fenamiphos(22224-92-6)

EPA Substance Registry System

Fenamiphos (22224-92-6)

Safety Information

Hazard Codes 

T+;N,N,T+

Risk Statements 

24-28-50/53-36-26/28

Safety Statements 

23-28-36/37-45-60-61-35-26

RIDADR 

UN 2811/3017

OEB

D

OEL

TWA: 0.1 mg/m3 [skin]

WGK Germany 

3

RTECS 

TB3675000

HazardClass 

6.1(a)

PackingGroup 

I

Hazardous Substances Data

22224-92-6(Hazardous Substances Data)

Toxicity

LD50 orally in rats (mg/kg): 10-25 (Waggoner, Khasawinah); LD50 orally in birds (mg/kg): 2.4 (Hill, Camardese)

Fenamiphos Usage And Synthesis

Description

Fenamiphos is a colourless crystal or a tan, waxy solid. It is non-corrosive to metals and breaks down readily in strong acids and bases. Fenamiphos is used as a nematicide and an insecticide for use on a wide variety of field, vegetable, and fruit crops. Fenamiphos has been used primarily to control nematodes and thrips on various agricultural crops (i.e., citrus, grapes, peanuts, pineapples, tobacco, etc.) and non-agricultural (i.e., turf and ornamentals) sites.Alternatively, it can also be used for the treatment of other kinds of invertebrates such as sucking insects and spider mite. Fenamiphos takes effects through inhibiting the acetylcholinesterase in the pests. There are no residential uses for fenamiphos and is a Restricted Use Pesticide (RUP) due to high acute toxicity and toxicity to wildlife.

References

https://pubchem.ncbi.nlm.nih.gov/compound/fenamiphos#section=Top
http://extoxnet.orst.edu/pips/fenamiph.htm

Description

Fenamiphos is a colorless crystalline substance. Solubility in water is 400 mg/L (20 ?C). It is soluble in polar organic solvents. Log Kow = 3.3(20 ?C). It is stable in aqueous media; DT₅₀ (22 ?C) at pH 4, 7, and 9 are 1, 8, and 3 yr.

Chemical Properties

Fenamiphos is a colorless crystal or a tan, waxy solid. It is non-corrosive to metals and breaks down readily in strong acids and bases. Fenamiphos is used as a nematicide and an insecticide. It is sparingly soluble in water, but readily soluble in dichloromethane, isopropanol, and toluene. It is used primarily for the control of nematodes and thrips on citrus, grapes, peanuts, pineapples, tobacco, turf, and ornamentals. There are no residential uses for fenamiphos. The US EPA has grouped fenamiphos as an RUP owing to its high acute toxicity and toxicity to wildlife. Reports have indicated that the manufacture and sale of fenamiphos is to be phased out by 2007–2008.

Chemical Properties

Yellow Solid

Uses

Nematocide and insecticide.

Uses

Fenamiphos is primarily used to control nematodes in a wide range of crops and in turf. It will also control mites and sucking insects in crops.

Uses

Systemic broad spectrum nematocide with anticholinesterase activity. Nematocide.

Definition

ChEBI: Fenamiphos is a phosphoramidate ester, an organophosphate insecticide and an organophosphate nematicide. It has a role as an EC 3.1.1.7 (acetylcholinesterase) inhibitor, an agrochemical and an acaricide. It is functionally related to a 4-(methylsulfanyl)-m-cresol.

General Description

Brown waxy solid or colorless solid. Used as a nematocide.

Air & Water Reactions

Fenamiphos is hydrolyzed by strong acids and strong alkalis.

Reactivity Profile

Organothiophosphates, such as Fenamiphos, are susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides.

Hazard

Toxic by inhalation and skin contact. Questionable carcinogen.

Health Hazard

Occupational exposures to fenamiphos cause severe toxicity and adverse health effects. It inhibits the activity of the cholinesterase enzyme in humans, leading to over stimulation of the nervous system. The symptoms of poisoning include, but are not restricted to, nausea, dizziness, confusion, impaired memory, disorientation, severe depression, irritability, headache, speech diffi culties, delayed reaction times, nightmares, sleepwalking, and drowsiness or insomnia. Very high exposures, such as accidental ingestion and/or major spillage, cause respiratory paralysis and death. Laboratory studies have indicated that the teratogenic effects of fenamiphos occurred only at levels that caused overt maternal toxicity and are likely indirect consequences of this toxicity. Other studies have indicated that fenamiphos is non-mutagenic and also have no evidence suggesting that fenamiphos is carcinogenic to animals and humans.

Health Hazard

Fenamiphos is highly toxic orally, by inhalation, and by absorption through the skin. (Non-Specific -- Parathion) Death may occur from respiratory failure.

Fire Hazard

(Non-Specific -- Organophosphorus Pesticide, n.o.s.) Container may explode in heat of fire. Fire and runoff from fire control water may produce irritating or poisonous gases. Emits toxic fumes of nitrogen oxides, phosphorus oxides, and sulfur oxides when heated to decomposition.

Flammability and Explosibility

Not classified

Agricultural Uses

Nematicide, Insecticide: A U.S. EPA restricted Use Pesticide (RUP). Fenamiphos is an organophosphate nematicide used to control a wide variety of nematode (roundworm) pests. Nematodes can live as parasites on the outside or the inside of a plant. They may be free living or associated with cyst and root-knot formations in plants. Fenamiphos is used on a variety of plants including tobacco, turf, bananas, pineapples, citrus and other fruit vines, some vegetables, and grains. The compound is absorbed by roots and is then distributed throughout the plant. Fenamiphos, as is typical of other organophosphates, blocks the enzyme acetylcholinesterase in the target pest. The pesticide also has secondary activity against other invertebrates such as sucking insects and spider mites.

Trade name

BAY 68138®; Bayer 68138®; NEMACUR®; NEMACURP®

Safety Profile

Poison by ingestion, inhalation, and skin contact. When heated to decomposition it emits very toxic fumes of NOx, POx, and SOx.

Potential Exposure

AgriculturalChemical; Reproductive Effector. Those involved in themanufacture, formulation, or application of this nematocide.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contactsthe skin, remove contaminated clothing and wash immediately with soap and water. Speed in removing materialfrom skin is of extreme importance. Shampoo hairpromptly if contaminated. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions,including resuscitation mask) if breathing has stopped andCPR if heart action has stopped. Transfer promptly to amedical facility. When this chemical has been swallowed,get medical attention. Give large quantities of water andinduce vomiting. Do not make an unconscious personvomit.

Environmental Fate

Soil. Oxidizes in soil to the corresponding sulfone and sulfoxide (Lee et al., 1986). Fenamiphos rapidly degraded in Arredondo soil to fenamiphos sulfone and at the sametime to the corresponding phenol. The half-life in this soil is 38–67 days (Ou and Rao, 1986).
Surface Water. In estuarine water, the half-life of fenamiphos was 1.80 days (Lacorte et al., 1995).
Chemical/Physical. Emits toxic fumes of phosphorus, nitrogen and sulfur oxides when heated to decomposition (Sax and Lewis, 1987; Lewis, 1990).

Metabolic pathway

Fenamiphos is an effective nematicide with both protectant and curative action. Free-living, ecto- and endo-parasitic, cyst-forming and root knot nematodes are controlled. Foliarly applied compound is translocated in plants to the roots and there is evidence that both translocation and optimum anti-cholinesterase and nematicide activity require oxidation of the thiomethyl group to the sulfoxide or the sulfone. These thiooxidation products are much more easily hydrolysed than fenamiphos itself and hydrolytic degradation in the environment most probably occurs via the formation of these intermediates.

Metabolism

The oxidation of the thiomethyl group to the sulfoxide and sulfone is required for both translocation and nematicidal activity in plants. The oxidation products are more susceptible to hydrolysis than fenamiphos itself. In mammals, orally administered fenamiphos is rapidly metabolized to the sulfoxide and sulfone, followed by subsequent hydrolysis, conjugation, and excretion in the urine. N-Dealkylation also occurs. The DT₅₀ in soils is several weeks; the major degradation products are fenamiphos sulfoxide and sulfone and their phenols.

storage

Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Store in tightly closed containers in a cool, well-ventilated area.

Shipping

This material falls under Organophosphorus pesticides, solid, toxic, n.o.s. This compound requires a shipping label of “POISONOUS/TOXIC MATERIALS.” It fallsin Hazard Class 6.1 and Packing Group I.

Toxicity evaluation

The acute oral LD₅₀ for rats is about 6 mg/kg. Inhalation LC50 (4 h) for rats is about 0.12 mg/L air. NOEL (2 yr) for rats is 1 mg/kg diet (0.05 mg/kg/d). ADI is 0.5 μg/kg b.w.

Degradation

For an organophosphorus compound, fenamiphos is relatively stable to hydrolysis. The DT₅₀s at pH values 4, 7 and 8 were 1 year, 8 years and 3 years respectively (PM). Fenamiphos was fairly stable in phosphate buffers at pH values 5 and 7 at 30-50 °C in the dark but in natural pond water containing silt the DT₅₀ was about 5 days. In pH 9 buffer the DT₅₀ was about 13 days. Under basic conditions the main product of hydrolysis was the phenol (2) (Waggoner and Khasawinah, 1974).
Walia and Dureja (1990) have studied the photolysis of fenamiphos in methanol solution irradiated by an unfiltered high pressure mercury lamp. The photosensitiser and singlet oxygen generator Rose Bengal was also included in one of the experiments. Analysis and characterisation were carried out by TLC, MS and ¹H NMR. In the presence of Rose Bengal the major product was fenamiphos sulfoxide (3). Since singlet oxygen is generated on soil surfaces and in silty water this experiment may be of relevance to the activation of fenamiphos in the environment. In the absence of a photosensitiser, the compound was cleaved to produce the phenol, 3-methyl-4-(methylthio)phenol (2) and its O-methylated derivative (not shown in Scheme 1), indicative of the involvement of methanol in the reaction. In an experiment which more closely mimicked the conditions for photodegradation in the environment, Barcelo et al. (1993) examined the photolysis of fenamiphos in water containing 24% methanol irradiated by a xenon arc (suntest) lamp. Metabolites were analysed and characterised by HPLC, thermospray MS and W (diode array) spectra. Fenamiphos was photodegraded to the extent of 98% after 90 min of irradiation. The main degradation product identified was fenamiphos sulfoxide (3). Products of the hydrolysis and photolysis of fenamiphos are shown in Scheme 1.

Incompatibilities

May hydrolyze under alkaline conditions.Keep away from moisture.

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