Diquat is a contact herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...

 that produces desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...

 and defoliation most often available as the dibromide, diquat dibromide. Brand names for this formulation include Aquacide, Dextrone, Preeglone, Deiquat, Detrone, Reglone, Reglon, Reglox, Ortho-Diquat and Weedtrine-D.

Diquat is a non-selective herbicide that acts quickly to damage only that parts of the plant to which it is applied. It breaks down quickly upon exposure to soil, leaving little residue.

Diquat dibromide is moderately toxic. It may be fatal to humans if swallowed, inhaled, or absorbed through the skin in sufficient quantities.


Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

 is oxidatively coupled to 2,2'-bipyridine
2,2'-Bipyridine is a organic compound with the formula . This colorless solid, commonly abbreviated bipy or bpy , is an important isomer of the bipyridine family. It is a bidentate chelating ligand, forming complexes with many transition metals...

 over a heated Raney nickel
Raney nickel
Raney nickel is a solid catalyst composed of fine grains of a nickel-aluminium alloy, used in many industrial processes. It was developed in 1926 by American]] engineer Murray Raney as an alternative catalyst for the hydrogenation of vegetable oils in industrial processes...

 catalyst. The ethylene bridge is formed by the reaction with 1,2-dibromoethane
1,2-Dibromoethane, also known as ethylene dibromide , is the chemical compound with the formula BrCH2CH2Br. Although trace amounts occur naturally in the ocean, where it is formed probably by algae and kelp, it is mainly a synthetic...

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