Naptalam

Naptalam
Names
	Other names Naptalam; Naptalam sodium; NPA;
Identifiers
CAS Number	132-66-1;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:60833;
ChEMBL	ChEMBL2447888;
ChemSpider	8275;
ECHA InfoCard	100.153.563
EC Number	625-029-1;
KEGG	C18869;
PubChem CID	8594;
UNII	306R88V86P;
CompTox Dashboard (EPA)	DTXSID6032437 ;
	InChI InChI=1S/C18H13NO3/c20-17(14-9-3-4-10-15(14)18(21)22)19-16-11-5-7-12-6-1-2-8-13(12)16/h1-11H,(H,19,20)(H,21,22) Key: JXTHEWSKYLZVJC-UHFFFAOYSA-N;
	SMILES C1=CC=C2C(=C1)C=CC=C2NC(=O)C3=CC=CC=C3C(=O)O;
Properties
Chemical formula	C18H12NO3
Molar mass	290.298 g·mol−1
Appearance	Purple solid
Melting point	185 °C (acid), 234 °C (sodium salt)
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Severe eye irritant
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	8200 mg/kg (acid), 1700 mg/kg (salt) (rat, oral)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Naptalam is a selective preёmergent herbicide, first registered in the US in 1949, to control sundry annual broadleaf weeds and grasses. Naptalam is a phthalic acid, though it is commonly also in sodium salt form.^[1] It is also used in Australia^[3] and Canada.^[4] In 1974, the USA used 4.94 million pounds (2,240 t) in agriculture.^[5]

Naptalam is unstable at temperatures over 180 °C or pH over 9.5.^[1]

Naptalam's mode of action makes it a Group P or Group 19 herbicide under the HRAC classification.^[3]

Application

Naptalam has been used on soybean, peanut, cucumber and melon crops, and ornamentals. Typical application rates are 2 to 6 lbs per acre (active ingredient), (2.25-6.75 kg/Ha). Formulations are usually water based liquids, or granular.^[1] While primarily preёmergent, naptalam may also be sprayed postemergently in some cases.^[4]

It has been sold under the tradename "Alanap-L" and "Rescue" in the US, and has been manufactured by Uniroyal,^[1] Chemtura and Vertac.^[3]^[6] "Alanap-3" is a 240 g/L formulation sold in Canada.^[4]

Environmental behaviour

In soil, naptalam is absorbed through the roots and translocated to the leaves. Soil mobility is high in fine sand, sandy loam, and silt loam; soil retention is increased with CEC and organic matter content.^[1]

Naptalam's toxicity is low for birds, fish, and aquatic invertebrates, presenting minimal hazard.^[1]

Safety

Naptalam is not carcinogenic, even at 5000 mg/kg, the highest dose tested on mice. It has some teratogenicity, so the EPA recommends a NOEL of 15 mg/kg/day. However, it causes irreversible eye damage, and is corrosive.^[1]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j "Pesticide Fact Sheet: Naptalam, 1985". nepis.epa.gov. US EPA.
^ "Pesticide Poisoning Action Guide Agricultural Pesticide In The Midwest Resource Directory 1994". nepis.epa.gov. US EPA.
^ ^a ^b ^c Hertfordshire, University of. "Naptalam (Ref: ACP 322)". sitem.herts.ac.uk.
^ ^a ^b ^c "ALANAP-3 LABEL" (PDF). bartlett.ca. Retrieved 4 May 2025.
^ "Pesticide Usage Survey, of Agricultural, Governmental and Industrial Sectors in the United States, 1974". nepis.epa.gov. Retrieved 3 May 2025.
^ "Pesticide Reregistration Progress Report 1992". nepis.epa.gov. NSCEP. Retrieved 3 May 2025.

External links

Naptalam in the Pesticide Properties DataBase (PPDB) (Naptalam)
Naptalam in the Pesticide Properties DataBase (PPDB) (Naptalam-sodium)

[epa_1985-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j "Pesticide Fact Sheet: Naptalam, 1985". nepis.epa.gov. US EPA.

[2] "Pesticide Poisoning Action Guide Agricultural Pesticide In The Midwest Resource Directory 1994". nepis.epa.gov. US EPA.

[database-3] Hertfordshire, University of. "Naptalam (Ref: ACP 322)". sitem.herts.ac.uk.

[alanap_canada-4] "ALANAP-3 LABEL" (PDF). bartlett.ca. Retrieved 4 May 2025.

[5] "Pesticide Usage Survey, of Agricultural, Governmental and Industrial Sectors in the United States, 1974". nepis.epa.gov. Retrieved 3 May 2025.

[6] "Pesticide Reregistration Progress Report 1992". nepis.epa.gov. NSCEP. Retrieved 3 May 2025.

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