Alkanol + HX

What happens when you add a concentrated hydrohalic acid, like hydrobromic acid or hydrochloric acid or hydroiodic acid, to an alkanol?
A substitution reaction!
Find out more in AUS-e-TUTE's new tutorial at https://www.ausetute.com.au/alkanolhx.html

AUS-e-TUTE Members should log-in to use the new tutorial, game and test (with worked solutions!).

Classification of Organic Reactions

Organic reactions are reactions in which the reactants and products are carbon-containing compounds, or organic compounds.
The chemical reactions that organic compounds take part in can be classified as:

• substitution reactions
• addition reactions
• elimination reactions
• oxidation reactions
• reduction reactions
• polymerisation reactions
• rearrangement reactions

AUS-e-TUTE has just added new resources including  a tutorial, game and test with worked solutions to help you identify and classify these types of organic reactions. AUS-e-TUTE Members should log-in to use these new resources.

If you are not an AUS-e-TUTE, a free-to-view tutorial is currently available at https://www.ausetute.com.au/organicrxn.html

Vanadium Phosphate Catalyst

Methane, CH₄, in natural gas can be used as a raw material to produce bromomethane, CH₃Br. Bromomethane (methyl bromide) can then be used in the chemical industry to produce fuels, chemicals, polymers and pharmaceuticals. When  bromomethane is converted into fuels and other chemicals, bromine is released in the form of hydrogen bromide, HBr. Using oxygen and a suitable catalyst, bromine from the hydrogen bromide by-product is embedded back into bromomethane so that no bromine is lost from the system.
Researchers at ETH, Zurich, have identified vanadium phosphate as an ideal catalyst for this reaction.
Vanadium(III) phosphate (vanadium(3+) phosphate), has the structure shown below:

It is a relatively mild oxidising catalyst.
It is a strong enough oxidising catalyst to allow hydrogen bromide to react with oxygen at the surface of the catalyst, but, it is not strong enough to oxidise the methane and brominated reaction products.
It is therefore possible to brominate methane in a single step at atmospheric pressure and at a temperature below 500°C.  The catalyst is also stable, able to resist the corrosive reaction environment.
This makes it an attractive catalyst for this important, industrial, chemical reaction.

Reference:
Vladimir Paunović, Guido Zichittella, Maximilian Moser, Amol P. Amrute, Javier Pérez-Ramírez. Catalyst design for natural-gas upgrading through oxybromination chemistry. Nature Chemistry, 2016; DOI:10.1038/nchem.2522

Further Reading:
Lewis Structures (electron dot diagrams): http://www.ausetute.com.au/lewisstr.html
2-Dimensional Structural Formula: http://www.ausetute.com.au/structural2D.html
Molecular Formula: http://www.ausetute.com.au/molecularformula.html
Halogenation of Hydrocarbons: http://www.ausetute.com.au/halogalk.html
Energy Profiles: http://www.ausetute.com.au/enerprof.html
Reaction Rates: http://www.ausetute.com.au/reactrate.html
Redox Reaction Concepts: http://www.ausetute.com.au/redoxreactions.html

Suggested Study Questions:

1. Draw the Lewis Structures (electron dot diagrams) for each of the following molecules:
   • methane
   • bromomethane
   • hydrogen bromide
2. Draw the 2-dimensional structural formula for each of the following molecules:
   • methane
   • bromomethane
   • hydrogen bromide
3. Give the molecular formula for each of the following molecules:
   • methane
   • bromomethane
   • hydrogen bromide
4. Write a chemical equation to represent the reaction between methane and bromine to produce bromomethane
5. Name the type of reaction given in question 4.
6. Give the reaction conditions necessary for this reaction in question 5 to occur at room temperature and pressure in your laboratory.
7. Why do you think a catalyst is required for this reaction above in order to produce commercial quantities of bromomethane?
8. Which organic compound, methane or bromomethane, do you expect to be the most chemically reactive? Explain your answer.
9. What is meant by the term "oxidising agent"?
10. Is the bromination of methane using bromine a redox reaction? Explain your answer.
11. Refer to the structure of vanadium(III) phosphate given in the article. Give the oxidation state (oxidation number) for each of the following:
    • vanadium
    • oxygen
    • phosphorus
12. Why do you think vanadium phosphate is talked about as being an "oxidising catalyst" rather than as an "oxidising agent"? Explain your answer.