1-naphthylacetic acid
Plant growth regulator
synthetic auxin
NOMENCLATURE
1-naphthylacetic acid
Common name 1-naphthylacetic acid (BSI, E-ISO, accepted in lieu of a common name); 1-naphthaleneacetic acid (alternative BSI, E-ISO name, in lieu of a common name); acide naphtylacétique (F-ISO, accepted in lieu of a common name)
IUPAC name 1-naphthylacetic acid
Chemical Abstracts name 1-naphthaleneacetic acid
Other names NAA; a-naphthaleneacetic acid CAS RN [86-87-3]
ethyl 1-naphthylacetate
CAS RN [2122-70-5]
PHYSICAL CHEMISTRY
1-naphthylacetic acid
Mol. wt. 186.2 M.f. C12H10O2 Form Colourless crystals. M.p. 134-135 ºC V.p. <0.01 mPa (25 ºC) Solubility In water 420 mg/l (20 ºC). In xylene 55, carbon tetrachloride 10.6 (both in g/l, 26 ºC). Readily soluble in alcohols and acetone. Soluble in diethyl ether and chloroform. Alkali-metal and amine salts are readily soluble in water. Stability Very stable in storage.
ethyl 1-naphthylacetate
Mol. wt. 214.3 M.f. C14H14O2 Form Colourless liquid. B.p. 175 ºC S.g./density 1.106 (25 ºC) Solubility Practically insoluble in water (20 ºC). Readily soluble in acetone, carbon disulfide, ethanol, isopropanol (20 ºC). Slightly soluble in kerosene, diesel oil. Stability Stable.
COMMERCIALISATION
History Plant growth-regulating activity reported by F. E. Gardiner et al. (Science, 1939, 90, 208). Introduced by Amchem Products, Inc. (now Bayer CropScience) and ICI Plant Protection Division (became Zeneca Agrochemicals, who ceased to manufacture or market it). Manufacturers Amvac; Bayer CropScience; Cyclo; Sharda
APPLICATIONS
1-naphthylacetic acid
Mode of action Promotes elongation and formation of roots, and acts as a growth inhibitor at higher concentrations. Uses To stimulate root formation in cuttings of woody and herbaceous plants, and vines; to prevent premature flower and fruit drop in apples, pears, grapes, guavas, mangoes, water melons, pawpaws, citrus fruits, aubergines, cucumbers, cotton, soya beans, etc.; to improve setting in fruit; as a fruit thinning agent in apples, pears, olives, citrus, and other fruit; and to induce flowering in pineapples. Formulation types DP; EC; SL; SP; TB; WP. Compatibility Solutions of the heavy-metal salts of other acids form sparingly-soluble salts of 1-naphthylacetic acid. Selected products: 'Acimone' (Devidayal); 'Fruit Fix' (ammonium salt) (Amvac); 'Fruitone' (sodium salt) (Amvac); 'Fruitone-N' (sodium salt) (Amvac); 'Rhizopon B' (Rhizopon, Fargro); mixtures: 'Vikipi' (+ 2-naphthyloxyacetic acid+ copper sulfate) (Vipesco)
ethyl 1-naphthylacetate
Mode of action Plant growth regulator with auxin-like activity. Uses Used to control aerial suckers from the roots of apple, pear, plum, cherry, and other fruit trees; to reduce water-shoot production in pruned apple and pear trees; and to inhibit sprouting at pruning points on ornamental trees. Formulation types AE; AL; Coating agent. Selected products: 'Tre-Hold' (Amvac)
OTHER PRODUCTS
1-naphthylacetic acid
'K Salt Fruit Fix' (potassium salt) (Amvac); 'Stik' (sodium salt) (Platte) mixtures: 'Amcotone' (+ 2-(1-naphthyl)acetamide) (Amvac); 'Synergol' (+ 4-indol-3-ylbutyric acid+ dichlorophen) (Hortichem); 'Vimix' (+ 2-naphthyloxyacetic acid+ validamycin) (Vipesco); 'Vipac 88' (+ 2-naphthyloxyacetic acid+ copper sulfate) (Vipesco); 'Viprom' (+ 2-naphthyloxyacetic acid+ copper sulfate) (Vipesco) Discontinued products: 'Celmone' * (Excel); 'Drofix' * (Productos OSA); 'Tipoff' * (Unicrop)
ethyl 1-naphthylacetate
'Prune Smart' (Amvac)
ANALYSIS
1-naphthylacetic acid
Product analysis by glc of a derivative. Residues determined by u.v. spectrophotometry (AOAC Methods, 17th Ed., 970.54*) or by hplc. Details available from Bayer CropScience.
ethyl 1-naphthylacetate
Product by glc.
MAMMALIAN TOXICOLOGY
1-naphthylacetic acid
Oral Acute oral LD50 for rats c. 1000-5900 mg/kg (acid), for mice c. 700 mg/kg (sodium salt). Skin and eye Acute percutaneous LD50 for rabbits >5000 mg/kg. Slight to moderate irritation of skin on prolonged contact; severe irritation to eyes (rabbits). Inhalation LC50 (1 h) >20 000 ppm. Toxicity class WHO (a.i.) U; EPA (formulation) III
ethyl 1-naphthylacetate
Oral Acute oral LD50 for rats c. 3580 mg/kg. Skin and eye Acute percutaneous LD50 for rabbits >2000 mg/kg. Slight to moderate irritation to skin on prolonged contact; non-irritating to eyes (rabbits). Inhalation LC50 for rats >206.5 mg/l.
ECOTOXICOLOGY
1-naphthylacetic acid
Birds Dietary LC50 (8 d) for mallard ducks and bobwhite quail >10 000 mg/kg diet. Fish LC50 (96 h) for rainbow trout 57, bluegill sunfish 82 mg a.i./l. Daphnia LC50 (48 h) 360 mg/l. Bees Not toxic to bees when used as directed.
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