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Methyl viologen dichloride hydrate


Paraquat dichloride, Gramoxone, 1,1′-Dimethyl-4,4′-bipyridinium dichloride
Empirical Formula (Hill Notation):
C12H14Cl2N2 · xH2O
CAS Number:
Molecular Weight:
257.16 (anhydrous basis)
MDL number:
PubChem Substance ID:

Quality Level




>300 °C (lit.)

SMILES string




InChI key



1 g in glass bottle
250 mg in glass bottle


Electron acceptor and transfer catalyst in redox reactions.

Signal Word


Hazard Classifications

Acute Tox. 2 Dermal - Acute Tox. 2 Inhalation - Acute Tox. 3 Oral - Aquatic Acute 1 - Aquatic Chronic 1 - Eye Irrit. 2 - Skin Irrit. 2 - STOT RE 1 - STOT SE 3

Target Organs

Respiratory system

Storage Class Code

6.1B - Non-combustible, acute toxic Cat. 1 and 2 / very toxic hazardous materials



Personal Protective Equipment

dust mask type N95 (US),Eyeshields,Gloves

Certificate of Analysis

Certificate of Origin

  1. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  2. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  3. How do I find price and availability?

    There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers.

  4. What is the absorbance maximum and extinction coefficient for Product 856177, Methyl viologen dichloride?

    The E1% in water is typically 650-700 at a wavelength of 258 nm. Given a molecular weight (corrected for water content for the trihydrate) of 311.2, this corresponds to a molar extinction coefficient (EM) of between 20,200 and 21,800. So you might want to use an average value of 21,000 in your calculations.

  5. Can Product 856177, Methyl viologen dichloride, be used in an assay for homocysteine. Do you have that reference?

    Yes. A colorimetric method is described for the detection of homocysteine over structurally related thiols, cysteine and glutathione has been described in the literature. When colorless solutions of methyl viologen are heated with cysteine, homocysteine and glutathione, only the solution with homocysteine changes color. The rapid method requires a few minutes and produces color changes which can be observed visually or with UV-VIS spectrophotometers. The method may lead to a diagnostic method for detection of homocysteine. J. Am. Chem. Soc., 126, 3400 (2004).

  6. I see that the molecular formula for Product 856177, Methyl viologen dichloride, lists the water content as X H2O. What is the typical value for X, and what is the corresponding molecular weight corrected for water content?

    This product typically assays at 15-18% water, corresponding to a trihydrate (X = 3). The molecular weight corrected for water content for the trihydrate is 311.2.

  7. How can Product 856177, Methyl viologen dichloride, be dissolved?

    We have found that this compound (methyl viologen) is soluble in water at 50 mg/mL.  According to the chemicals encyclopedia published by the Royal Society of Chemistry, 12th Ed., entry #7165, methyl viologen is very soluble in water, slightly soluble in the lower alcohols and insoluble in hydrocarbons; it is hydrolyzed by alkali and inactivated by inert clays and anionic surfactants.

  8. Do you have a literature protocol for preparing the reduced form of Product 856177, Methyl viologen dichloride?

    Yes. The reference is Trudinger, P.A., Anal. Biochem., 36, 222-251, 1970. Here is the procedure:Reduced methyl viologen was prepared as follows: 20-30 μl of 0.1 M sodium dithionite in 0.1 M Tris, pH 8.0, was injected into 3 mL of nitrogen-flushed solutions of 0.1 mM methyl viologen. Removal of the oxygen, as much as possible, helps to inhibit the reoxidation of the reduced methyl viologen. In distilled water and neutral or acid buffers, reduction with sodium dithionite gave variable values in their determination of the extinctions of reduced methyl viologen. It appeared that alkaline pH's, i.e., ~8, may be preferable. Methyl Viologen (reduced) has been used as the substrate for nitrate reductase (cytochrome), Sigma product N0519. It is important that all reagents be virtually free of oxygen in order to prevent the oxidation of the reduced methyl viologen substrate or else no enzymatic reaction will occur. Towards this end all reagents are dissolved in deionized water which has been boiled for 10 minutes, then cooled. After cooling, the water is degassed under vacuum to further ensure the removal of oxygen. After reagents are prepared, they are stored in vials which are tightly capped, then stored on ice at 0-5 °C. It is best to have no more than a minimum volume of air in these containers.In our experience, for the reduction of methyl viologen using sodium dithionite, it is important to use anhydrous sodium dithionite, since the reducing power of the moist salt may be diminished.

  9. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

  10. In what solvents is Methyl viologen dichloride hydrate, Product 856177, soluble?

    According to the chemicals encyclopedia published by the Royal Society of Chemistry, methyl viologen dichloride hydrate is very soluble in water, slightly soluble in lower alcohols and insoluble in hydrocarbon solvents.

  11. What is the stability of Methyl viologen dichloride hydrate, Product 856177, in solution?

    Unfortunately, we have not performed stability testing of methyl viologen dichloride hydrate in solution. Therefore, we would recommend you make a fresh solution before each use.

  12. How many moles of water are present in Methyl viologen dichloride hydrate, Product 856177?

    The water content of each lot of this product is tested by Karl Fischer titration. The weight percent of water will be reported on the certificate of analysis of each lot.

  13. My question is not addressed here, how can I contact Technical Service for assistance?

    Ask a Scientist here.

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