2764-72-9

Basic information

• Product Name: Diquat ion
• Synonyms: 6,7-Dihydro-5,8-didehydrodipyrido[1,2-a:2',1'-c]pyrazine-5,8-diium;6,7-Dihydrodipyrido[1,2-a:2',1'-c]pyrazine-5,8-diium;9,10-dihydro-8a,10a-diazoniaphenanthrene ion,diquat;D004178;Dibromide, diquat;1,1'-ethylene-2,2'-bipyridylium;6,7-dihydrodipyrido[1,2-a:2',1'-c]pyrazinediium;9,10-Dihydro-8a,10a-diazoniaphenanthrene
• CAS NO: 2764-72-9
• Molecular Formula: C₁₂H₁₂N₂
• Molecular Weight: 184.24
• EINECS: 220-433-0
• Mol File: 2764-72-9.mol
• Article Data: 8

Chemical Properties

• Appearance: yellow crystalline solid
• CAS DataBase Reference: Diquat ion(CAS DataBase Reference)
• NIST Chemistry Reference: Diquat ion(2764-72-9)
• EPA Substance Registry System: Diquat ion(2764-72-9)

Safety Data

• RIDADR: UN2781
• Hazardous Substances Data: 2764-72-9(Hazardous Substances Data)

Usage

Uses

Used in Agricultural Industry:
Diquat ion is used as a herbicide and desiccant for various agricultural applications. As a nonselective, quick-acting herbicide and plant growth regulator, it causes injury only to the parts of the plant to which it is applied. Diquat is referred to as a desiccant because it causes a leaf or an entire plant to dry out quickly.
1. Potato Vine Desiccation: Diquat ion is used to desiccate potato vines, aiding in the harvesting process and reducing the time required for the plants to dry naturally.
2. Seed Crop Drying: It is employed to dry seed crops, ensuring that the seeds are ready for harvesting and storage without the need for prolonged drying periods.
3. Sugarcane Flower Control: Diquat ion is used to control the flowering of sugarcane, which can negatively impact the quality and yield of the crop.
4. Industrial and Aquatic Weed Control: It is utilized for weed control in industrial and aquatic environments, such as catfish farms, to maintain a clean and healthy ecosystem.

Production Methods

Diquat is manufactured in the United Kingdom by the oxidative coupling of two molecules of pyridine over a heated Raney nickel catalyst to produce 2,20-bipyridyl, which is reacted with ethylene dibromide in water to give diquat dibromide. It is formulated worldwide in various water-soluble products and in various concentrations, typically 2 lb/gal.

Air & Water Reactions

Water soluble. Solutions are stable in neutral and acid solutions; however, they are unstable in alkaline solutions.

Reactivity Profile

Diquat ion is light sensitive. Diquat ion can corrode aluminum and other metals.

Health Hazard

INHALATION: No appreciable vapor pressure. Prolonged contact with spray or mist may cause oral and nasal irritation. EYES: Irritation. SKIN: Irritation. INGESTION: Vomiting, diarrhea, general malaise. Possible kidney and liver damage, dyspnea, and pulmonary edema. With large doses there may be tremors or convulsions. OTHER: May be fatal if swallowed, inhaled, or absorbed through skin.

Fire Hazard

Behavior in Fire: Decomposes at high temperature, charring rather than melting or boiling.

Trade name

AQUACIDE?; AQUA-CLEAR?[C] AQUAKILL?; CLEANSWEEP?; DEIQUAT?; DEXTRONE?; FARMON PDQ?; FB/2?; FEGLOX?; GROUNDHOG SOLTAIR?; ORTHO DIQUAT?; PATHCLEAR?; PREEGLONE?; REGLON?; REGLONE?; Zeneca Ag Products; REGLOX?; REWARD?; TAG?; TORPEDO?; VEGATROLE?; WEEDOL (ICI)?; WEEDTRINE-D?

Carcinogenicity

Several carcinogenicity studies have been conducted on diquat by the oral route. In a 2-year feeding study at doses as high as 75 mg/kg in mice, and a drinking water study at doses as high as 2.6 mg/L of water in rats, no evidence of tumorigenicity was seen. Similar negative results were reported for diquat in a 2-year feeding study (Hayes, 1991) in rats at dose levels up to 720 mg/kg and in a 2-year drinking water study in mice at doses of 2–4 mg/kg.

Upstream product

• 366-18-7 [2,2]bipyridinyl 
• 85-00-7 diquat dibromide 
• 1762-34-1 5,5'-dimethyl-2,2'-bipyridine 
• 106-93-4 ethylene dibromide 

Relevant articles and documents

Optimizing electron transfer from CdSe QDs to hydrogenase for photocatalytic H2 production

A series of viologen related redox mediators of varying reduction potential has been characterized and their utility as electron shuttles between CdSe quantum dots and hydrogenase enzyme has been demonstrated. Tuning the mediator LUMO energy optimizes the performance of this hybrid photocatalytic system by balancing electron transfer rates of the shuttle.

Reactions of Three Bis(viologen) Tetraquaternary Salts and Their Reduced Radicals

Monoradical trications X3+. and diradical dications X2+.. were produced by reduction of three bis(viologen) X4+ (1,1''-alkanediylbis(1'-alkyl-4,4'-bipyridinium)) tetraquaternary salts.The spectral properties of X3+. and its disproportionation kinetics were examined by eaq-/CO2- reduction of X4+.Reduction potentials of the X4+/3+ and X3+/2+ couples were determined by cyclic voltametry and spectral examination of equilibrated mixtures of X4+ and X2+.. radicals.These potentials were used to apply successfully the Marcus theory to reduction of X4+ by SO2- and oxidation of X3+. and of X2+.. by O2 and cobalt(III) complexes.The reactivity toward O2 and the comproportionation of X2+.. (with X4+) is believed to be influenced by the tendency of X2+.. to form an intramolecularly associated conformation.

Effect of structural change in viologen acceptors on the rate of single electron transfer from tributylphosphine

The "flexible" 3 and "rigid" cyclic viologens 4, diquarternary salts of 2,2′-bipyridine and 1,10-phenanthroline, respectively, were treated with tributylphosphine (1) in acetonitrile containing a large amount of methanol under an argon atmosphere. A single electron transfer (SET) easily occurred from the latter to the former, the SET to 4 being 105-106 times faster than the SET to 3. The reorganization energy λ for the latter SET is thought to be larger than that for the former SET, because 3 undergoes a structural change upon the one-electron reduction to its radical cation, whereas the one-electron reduction of 4 takes place without a structural change. Taking into account the difference in λ, and also taking into account the bond formation energy brought about by the follow-up reaction of the phosphine radical cation 1 + with methanol, the observed kinetics were well interpreted in terms of the Marcus theory. The Royal Society of Chemistry 2006.

Kinetics of Reduction of Eight Viologens by dithionite Ion

The rate constants are reported for reduction by dithionite of methyl viologen, diquat, and six other diquaternary salts of 4,4'-bipyridine, 2,2'-bipyridine, and 1,10-phenanthroline.The active reductant is the SO2(1-) radical, and rate constants vary from >5*108, to 8.5*103 M-1s-1 with increasing negative reduction potential of the viologen.It is concluded that self-exchange rate constants for the viologens (X2+/+ couple) are ca. 108 M-1s-1, and it is supported by the results of a cross-reaction involving two viologens, the second-oreder rate constant being measured by pulse radiolytic techniques.

Radical Cations of some Low-potential Viologen Compounds; Reduction Potentials and Electron-transfer Reactions

The one-electron reduction potentials (E1) of certain pyrazinediium, diazepinediium and diazocinediium viologen compounds substituted with methyl groups, V(2+), have been determined from the position of the one-electron transfer equilibria with reference compounds using pulse radiolysis.E1 ranges from -491 +/- 6 mV (vs NHE) for 6,7-dihydro-2,11-dimethyldipyridopyrazinediium dibromide (V21(2+)) to -832 +/- 11 mV for 6,7,8,9-tetrahydro-2,3,12,13-tetramethyldipyridodiazocinediium dibromide (V42(2+)).The rates of reduction by e(1-)aq were found to be independent of E1 whereas the rates of electron transfer from CO2(1-). and (CH3)2C.OH species do show a dependence on E1 for V(2+) compounds of lowest E1.Marcus-type treatment of the rate-constant data yields a rate constant of electron exchange between propan-2-oxyl radicals and acetone in the range (2-6)E6 dm3mol-1s-1 and between the radical cation of 6,7-dihydro-2,3,10,11-tetramethyldipyridopyrazinediium dibromide (V22.(1+)) and its unreduced form (V22(2+)) of 5E7 dm3mol-1s-1.

Magnetic Resonance Studies of Some Bipyridylium Diactions and Cation Radicals

In an attempt to resolve ambiguities in and contradictions among previous studies, NMR spectra of the methylviologen (MV2+), benzylviologen (BV2+), and diquat (DQ2+) dications and ESR spectra of the corresponding cation radicals were reinvestigated.ESR spectra of the cation radicals in methanol solution had sufficiently good signal-to-noise ratios and resolution to permit completely unambiguous determinations of hyperfine coupling constants.ESR intensity data showed that MV+. and BV+. precipitate as ESR-inactive solids at low temperature and that MV+. associates to micelle-like solution particles at high concentration.The intensity data show no evidence for formation of dimers or other low molecular weight polymers.Literature reports of dimer formation in methanol solution are the result of temperature-dependent saturation of the ESR spectra.Line broadening of NMR spetra of MV2+, BV2+, or DQ2+ in the presence of traces of cation radical was used to provide unambiguous assignments of ESR hyperfine coupling constants, and to give good estimates of the cation radical concentrations and the dication/cation radical electron exchange rate constant.The NMR line broadening experiments also provide an estimate of the rate of conformational change of the ethylene bridge in the diquat cation radical.

Rates and Mechanism for Oxidation of Paraquat and Diquat Radical Cations by Several Peroxides

The rates of oxidation of the free radicals MV(+)-radicals and DQ(+)-radicals derived from herbicides Paraquat and Diquat by hydrogen peroxide, peroxodiphosphate species, and peroxodisulfate have been investigated.Where consistent data were obtainable, the reactions are first order each in peroxide and radical.Results for H2O2 and MV(+)-radical are k = 2.0 (M*s)-1 at 25 deg C, ΔH(excit.) = 92 kJ*mol-1, and ΔS(excit.) = 73 J*(mol*K)-1; similar results were found with H2O2 and DQ(+)-radical.Although hydroxyl radicals are likely intermediates, the predicted inhibition when methanol is present did not materialize; a mechanistic rationalization is presented.The rates with peroxodiphosphate were pH dependent and could be interpreted as different contributions from H2P2O8(2-), HP2O8(3-), and P2O8(4-) in the same order as found for peroxodiphosphate and unstable radicals.The rate with S2O8(2-) is fastest, but complications prevented the evaluation of a rate constant.