National Toxicology Program

National Toxicology Program
http://ntp.niehs.nih.gov/go/chemical-94-75-7

CAS Registry Number: 94-75-7

Selected information from two of the National Library of Medicine's databases: ChemIDPlus1 and HSDB2.

Names (NTP)

  • 2,4-D (PEROXISOME PROJECT)
  • 2,4-D
  • 2,4-Dichlorophenoxyacetic acid
  • Peroxisome project (2,4-Dichlorophenoxyacetic acid)

Structure

Chemical Structure for Chemical Abstracts Service Registry Number 94-75-7 from NLM

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Chemical Properties2

Property Description
Color/Form
  • White to yellow crystalline powder /SRP: yellow color is phenolic impurities/
  • Colorless powder
  • White to yellow, crystalline ... powder.
  • Crystals from benzene
Odor
  • ODORLESS WHEN PURE
  • A slight phenolic odor
Taste
  • None found
Boiling Point
  • 160 deg C @ 0.4 mm Hg
Melting Point
  • 138 deg C
Molecular Weight
  • 221.04
Corrosivity
  • Free acid is corrosive to metals.
  • Most formulations are noncorrosive to spray equipment although some concentrates may be deleterious to painted surfaces.
Critical Temperature & Pressure
  • None found
Density/Specific Gravity
  • 1.42 @ 25 deg C
Disassociation Constants
  • pKa= 2.73
Heat of Combustion
  • -7700 BTU/lb= -4300 cal/g= -180X10+5 J/kg
Heat of Vaporization
  • None found
log P (octanol-water)
  • log Kow= 2.81
pH
  • None found
Solubilities
  • 67.3 g/400 ml acetone at 25 deg C; 0.94 g/100 ml benzene at 28 deg C; 0.63 g/100 ml carbon disulfide at 29 deg C; 0.16 g/100 ml carbon tetrachloride at 25 deg C; 0.08 g/100 ml diesel oil and kerosene at 25 deg C; 78.5 g/100 ml dioxane at 31 deg C; 10.3 g/100 ml ethanol (50%) at 25 deg C; 100 g/100 ml ethyl alcohol (95%) at 25 deg C; 27.0 g/100 ml ethyl ether at 25 deg C; 24.8 g/100 ml isopropanol at 31 deg C; 25 g/100 ml methyl isobutyl ketone at 25 deg C; 0.52 g/100 ml ortho-dichlorobenzene at 25 deg C; 0.058 g/100 ml toluene at 25 deg C
  • INSOL IN PETROLEUM OILS
  • 1.1 g/kg n-heptane at 20 deg C
  • 540 PPM IN WATER AT 20 DEG C
  • In water, 677 ppm @ 25 deg C.
Spectral Properties
  • SADTLER REF NUMBER: 13141 (IR, PRISM); 8174 (IR, GRATING); MAX ABSORPTION (WATER, 0.1 N HCL): 282 NM (LOG E= 3.26); 289 NM (LOG E= 3.20) SHOULDER
  • The undissociated molecule in 0.1 M hydrochloric acid has a molar absorptivity of 1820 molar/cm at 282 nm; the anion in 0.01 M phosphate buffer is 2070 at 283.5 nm.
  • IR: 2221 (Coblentz Society Spectral Collection)
  • UV: 3427 (Sadtler Research Laboratories Spectral Collection)
  • 1H-NMR: 10803 (Sadtler Research Laboratories Spectral Collection)
  • MASS: 52494 (NIST/EPA/MSDC Mass Spectral Database 1990 Version)
  • Intense mass spectral peaks: 162 m/z (100%), 164 m/z (69%), 220 m/z (61%), 222 m/z (39%)
  • Intense mass spectral peaks: 111 m/z, 133 m/z, 175 m/z
Surface Tension
  • 66.5 dyne/cm at 25 deg C and pH 1.4
Vapor Density
  • None found
Vapor Pressure
  • 8.25X10-8 mm Hg @ 20 deg C (1.1X10-2 mPa @ 20 deg C)
Relative Evaporation Rate
  • None found
Viscosity
  • None found
Other Properties
  • Percent adsorbed by 10 mg activated carbon from 1X10-4 M aqueous solution @ pH 3.0: 60.1%; @ pH 7.0: 18.8%; at pH 11.0: 14.3%.
  • NON-HYGROSCOPIC
  • polarizability= 227.4; Latent heat of fusion= 5.6 kcal/mol; Dipole moment= 3.33 debye
  • Proton NMR: Free 2,4-D in CD3OD shows no free H downfield of the aromatic absorptions, but shows an exchange peak with CD3OD at 5.13 ppm relative to TMS. The CH2 group absorbs at 4.72 ppm, H-3 /of the ring/ at 7.35, H-5 at 7.12, and H-6 at 6.90 ppm.
  • Henry's Law constant = 8.6X10-6 atm-cu m/mole @ 20 deg C

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Uses2

  • For 2,4-D (USEPA/OPP Pesticide Code: 030001) ACTIVE products with label matches. /SRP: Registered for use in the U.S. but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses./
  • Herbicide used on grasses, wheat, barley, oats, sorghum, corn, sugarcane, & noncrop areas /pasture & range land; lawns & turf/ for post-emergent control of canada thistle, dandelion, annual mustards, ragweed, lambsquarters & others. Some formulations for pine release, water hyacinth control & prevention of seed formation; double-gee, wild radish, turnip & other broadleaf weeds in cereals.
  • Registered for use on rice in the Philipines.
  • 2,4-D when applied properly, will increase the red color in potatos. It is used on tomatos to cause all fruits to ripen at the same time for machine harvesting.
  • /2,4-D free/ acid serves as the basic material from which the soluble esters & salts are produced.
  • Used in forest management: Brush control; Conifer release; Tree injection.
  • To increase latex output of old rubber trees.
  • HERBICIDE FOR PASTURE & RANGELANDS; AGRICULTURAL USE-EG, WHEAT, CORN, GRAIN SORGHUM, RICE AND OTHER GRAINS; INDUSTRIAL/COMMERCIAL USES; LAWNS, TURF, & AQUATIC USE; OTHER FIELD CROPS-EG, NUTS; COMPONENT OF HERBICIDE FOR JUNGLE DEFOLIATION-FORMER USE.
  • 2,4-D, its salts & esters are systemic herbicides, widely used for weed control in cereals & other crops at 0.28-2.3 kg/ha.
  • Chlorophenoxy compounds including acids, salts, amines & esters are ... /used/ in agriculture for control of broad-leaf weeds & in control of woody plants along roadside, railways & utilities rights of way. /Chlorophenoxy compounds/
  • 2,4-D is used as a ... plant growth regulator. It is a component of Agent Orange, a military defoliant.

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Superlist Classes1

  • Reportable Quantity (RQ) = 100 lb
  • TWA 10 mg/m3; Not classifiable as a human carcinogen
  • TWA 10 mg/m3
  • 2007 CERCLA Priority List, Rank: 248
  • 2011 CERCLA Priority List, Rank: 243

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Notes (Sources: NTP,HSDB,RTECS,MESH)1

  • None found

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Other Registry Numbers1

  • 15183-39-8

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Synonyms (Sources: NTP, HSDB,RTECS,MESH)1

  • U 46DP
  • U-5043
  • 2,4-D acid
  • 4-06-00-00908 (Beilstein Handbook Reference)
  • R-H Weed Rhap 20
  • Acme LV 4
  • Acme LV 6
  • Agricorn D
  • Agrotect
  • Amoxone
  • Barrage
  • BH 2,4-D
  • BRN 1214242
  • Brush-rhap
  • Chipco turf herbicide "D"
  • Chloroxone
  • Citrus fix
  • Crop rider
  • Croprider
  • Debroussaillant 600
  • Deherban
  • De-Pester Ded-Weed LV-2
  • Dichlorophenoxyacetic acid
  • Dicopur
  • Dormon
  • Dormone
  • Emulsamine
  • Emulsamine E-3
  • Emulsamine BK
  • ENT 8,538
  • Envert DT
  • Estone
  • Fernesta
  • Fernimine
  • Ferxone
  • Foredex 75
  • Green Cross Weed-No-More "80"
  • Hedonal (the herbicide)
  • Herbidal
  • Hivol-44
  • HSDB 202
  • Ipaner
  • Lawn-keep
  • Macondray
  • Macrondray
  • Miracle
  • Mota Maskros
  • Moxon
  • Moxone
  • Netagrone
  • Netagrone 600
  • 2,4-PA
  • Pennamine D
  • Phenox
  • Phenoxyacetic acid, 2,4-dichloro-
  • Pielik
  • Plantgard
  • RCRA waste number U240
  • Red Devil Dry Weed Killer
  • Rhodia
  • Scott's 4-XD Weed Control
  • B-Selektonon
  • Silvaprop 1
  • Superormone concentre
  • Tributon
  • Vergemaster
  • Verton 2D
  • Verton 38
  • Vidon 638
  • Weed TOX
  • Weed-Ag-Bar
  • Weedatul
  • Weedez Wonder BAR
  • Weed-B-gon
  • Weedone
  • Weedone LV4
  • Weed-rhap
  • Weed-Rhap A-4
  • Weed-Rhap B-266
  • Weed-Rhap B-4
  • Weed-Rhap I-3.34
  • Weed-Rhap LV-4-0
  • Weedtrol

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Links to Additional Information1

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Footnotes

1 Source: the National Library of Medicine's ChemIDPlus, 04/28/2013.

2 Source: the National Library of Medicine's Hazardous Substance Database, 12/12/2012.

The NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.