Producing Organic Compounds from Bip-oils

Many chemical feedstocks such as ethene and propene, the building blocks of many plastics, as well as aromatic compounds such as benzene and toluene used in dyes and plastics, are currently produced from petroleum.
University of Massachusetts Amherst scientists have reported that they have developed a way to produce these feedstocks from pyrolytic bio-oils, the cheapest liquid fuels available today derived from biomass. These pyrolytic bio-oils can be made from non-food agricultural crops and woody biomass.
The two-step, integrated catalytic approach starts with a "tunable", variable-reaction hydrogenation stage followed by a second, zeolite catalytic step. The zeolite catalyst has the proper pore structure and active sites to convert biomass-based molecules into aromatic hydrocarbons and alkenes.

Journal Reference
Tushar P. Vispute, Huiyan Zhang, Aimaro Sanna, Rui Xiao, and George W. Huber. Renewable Chemical Commodity Feedstocks from Integrated Catalytic Processing of Pyrolysis Oils. Science, 26 November 2010: 1222-1227 DOI: 10.1126/science.1194218

Further Reading
Nomenclature of Carbon Compounds
Naming Simple Alkenes
Ethene: properties, production and uses
Polythene: properties, production and uses
Polymers and Polymerization

Study Questions

1. Give the molecular formula and structural formula for ethene.
2. Give the molecular formula and structural formula for propene.
3. Give the molecular formula and structural formula for benzene.
4. Give the molecular formula and structural formula for toluene.
5. What is meant when an organic chemist refers to hydrogenation?
6. What is meant by the term pyrolytic?
   
7. Write an equation for the hydrogenation of ethene.
8. Write an equation for the hydrogenation of propene.
9. Why is benzene classed as an aromatic compound and not as an alkene?
   

Tasty Chemistry

Taste refers to the ability to detect the flavour of substances. We receive tastes through sensory organs called taste buds which are concentrated on the upper surface of the tongue.
Among the 50 or so cells in each taste bud there are cells responding to each of the five tastes:

• sweetness
• bitterness
• sourness
• saltiness
• umami-ness or savoriness
  

Sweetness is often associated with foods rich in simple carbohydrates such as glucose and sucrose, but many compounds taste sweet. Examples include the amino acids alanine, glycine and serine as well as the glycosides glycyrrhizin (found in licorice root) and stevioside (from the Stevia rebaudiana shrub). Even some inorganic compounds, such as beryllium chloride and lead acetate, taste sweet.

Bitterness is perceived by many people to be unpleasant. It helps prevent us ingesting toxic substances. A bitterant is the chemical that makes a substance taste bitter. Examples of bitterants are sucrose octaacetate which is used as an inert ingredient in pesticides and herbicides, and, brucine which is a bitter alkaloid closely related to strychnine that is found naturally in a number of plant species.

Sourness is the sensation evoked by substances that are acidic such as lemons and pickles. The acids we ingest release protons which enter the cell and cause a direct, detectable, electronic response.

Saltiness is the taste produced by the presence of alkali metal cations such as Na⁺ and K⁺. The less sodium-like the ion is, the less salty the sensation will be, eg, Rb⁺ and Cs⁺ ions are larger than Na⁺ ions so they do not taste as salty.

The umami taste is due to the detection of the carboxylate anion of glutamic acid, a naturally occurring amino acid found in meat, cheese, and other protein-rich foods. Glutamates, the salts of glutamic acid, easily ionize resulting in the same carboxylate anions and therefore producing the same umami taste. As a consequence, glutamates are often used as flavour enhancers, the most common of which is monosodium glutamate (MSG).

Further Reading
Carbohydrates (sugars)
Amino Acids
Properties of Acids and Bases

Study Questions

1. Name the 3 elements common to all carbohydrates.
2. What is the structural difference between molecules classified as monosaccharides and those that are classed as disaccharides or polysaccharides?
   
3. Is glucose an example of a monosaccharide, a disaccharide or a polysaccharide?
4. Is sucrose an example of a monosaccharide, a disaccharide or a polysaccharide?
5. What elements are common to all amino acids?
6. What functional group or groups must a molecule contain in order for it be classified as an amino acid?
7. Draw the structures for glycine, alanine and serine. Identify the functional groups present in each molecule.
8. A number of amino acids are said to taste sweet, but acids generally are said to taste sour. Can you explain these apparently contradictory statements?
   

Cardanol

Chemists at The City College of New York have designed a molecule which has both water-adhering and water-repelling ends, from cardanol (the structure on the right), a naturally available material found in cashew nutshell liquid.

When mixed with water, the designer molecules formed a self-assembled structure called a micelle with a water-adhering exterior and water-repelling interior.

At 50^oC the micelles take on a 3-dimensional structure known as a vesicle that is about 200 times larger and more viscous. The molecules stick together enough to be draw out into a thin strand, just like glue.

Cooling the material allows the molecules to revert to their original micellar structure.

Heating causes the micelles to re-arrange themselves into an interlocking bi-layer which undergoes curvature. The structure is stabilized in part by the hydrogen bonding.

Reference
Vijai S. Balachandran, Swapnil R. Jadhav, Padmanava Pradhan, Sacha De Carlo, George John. Adhesive Vesicles through Adaptive Response of a Biobased Surfactant. Angewandte Chemie International Edition, 2010; DOI: 10.1002/anie.201005439

Further Reading
Detergents
Soaps and Saponification
Functional Groups
Percentage Composition
Intermolecular Forces
Intramolecular Forces

Study Questions

1. Identify the functional groups present in a molecule of cardanol.
2. Give the molecular formula for cardanol.
3. Calculate the percentage of carbon, hydrogen and oxygen present in a mole of cardanol.
4. On the molecular structure of cardanol, identify the water-adhering area and the water-repelling area.
5. What is the name given to a molecule that adheres to water?
6. What name is given to a molecule the repels water?
7. Draw a diagram to show how cardanol molecules could form a micelle.
8. Given the description of the behaviour of the designer molecule in the article above, in what ways do you think it differs from the structure of cardanol?
   

Ammonia Production

Ammonia (NH₃) is one of the most important chemicals in the modern world, mostly due to its use in the manufacture of artificial fertilisers. The Haber, or Haber-Bosch process, is used to produce ammonia and is vital to the production of 100 million tons of fertiliser per year, responsible for sustaining one-third of the Earth's population.

Ammonia is generated naturally by plants and certain bacteria, which extract nitrogen from the atmosphere in a process known as nitrogen fixation. Natural nitrogen fixation occurs at ambient temperatures and pressures, but artificial nitrogen fixation via the Haber-Bosch process requires high pressures (150-250 atmospheres) and high temperatures (300-550 degrees Celsius) to produce the vast quantities of ammonia necessary to satisfy global demand.

The key to the Haber-Bosch process is an iron catalyst which encourages the dissociation of N₂ molecules, and provides a platform on which the resulting N atoms can be successively hydrogenated to yield NH, NH₂ and finally NH₃.

Scientists at the University of Cambridge exposed their iron sample to nitrogen ions, in order to readily build up a coverage of nitrogen atoms on the surface (to a density of just over one nitrogen atom per two top-layer iron atoms at the surface). Under uhv conditions, they can utilise Auger Electron Spectroscopy (AES) to quantify the amount of nitrogen on the surface. Then, they expose the sample to 0.6 mbar H₂ gas for a period of several minutes. This pressure is still very low compared with industrial conditions, but it allows the reaction to proceed sufficiently rapidly for them to take meaningful measurements over a timescale of minutes. If they used only uhv pressures of H₂, the reaction would be so slow that it would take hours, during which time contamination would build up on the surface and ruin the experiment.
After an exposure of several minutes, they rapidly evacuate the experimental chamber to return to uhv conditions and use AES to evaluate how much nitrogen is left on the surface, then expose to H₂ again and repeat. By doing this several times, they can measure the drop in surface nitrogen (corresponding to production of ammonia) as a function of time and temperature.

Their results suggest that, under certain conditions, namely when the ammonia pressure is kept low, the hydrogenation steps (from N to NH to NH₂ to NH₃) may actually be the most important.

Journal Reference:

1. Poobalasuntharam Iyngaran, David C. Madden, Stephen J. Jenkins, David A. King. Hydrogenation of N over Fe{111}. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1006634107

Further Reading
Haber Process
Nitrogen Cycle

Study Questions

1. Write a balanced chemical equation for the production of ammonia from hydrogen and nitrogen gas.
2. Predict the effect of high pressure in the reaction vessel on the yield of ammonia.
3. The Haber Process is an exothermic reaction. Explain what is meant by the term exothermic.
4. Explain what would happen to the yield of ammonia if the reaction vessel were cooled.
5. It is estimated that between 3 and 5% of the world's natural gas production is used in the production of ammonia. What would the natural gas be used for in the is process?
6. The Haber process typically produces an ammonia yield of between 10 and 20%. Describe 4 ways that this yield could be improved.
7. In the article above it is said that measuring the drop in surface nitrogen corresponds to measuring production of ammonia. Explain why this is true.
8. Describe another way you could measure the production of ammonia.
   

Luminol - Detecting Blood

Luminol is a common reagent used to detect blood stains and other body fluids at crime scenes because it reacts with iron in blood to produce a blue glow.
Its IUPAC name is 5-amino-2,3-dihydro-1,4-phthalazinedione.

The luminol solution used by crime scene investigators is a solution of luminol and an activator, an oxidant such as hydrogen peroxide and a hydroxide salt in water. In the presence of a catalyst, such as the iron in haemoglobin, the hydrogen peroxide decomposes to form oxygen and water and the luminol reacts with the hydroxide salt to form a dianion. The oxygen produced during the decomposition reaction reacts with luminol dianion producing an organic peroxide which is very unstable and immediately decomposes to produce 3-aminophthalic acid with electrons in the excited state. As the excited state electrons relax to the ground state, energy is released as visible blue light.

Unfortunately, luminol reacts with other substances besides the iron in haemoglobin such as copper, bleaches and horseradish.

University of South Carolina Chemists are using a new thermal infrared technology to illuminate blood stained objects with pulses of invisible infrared waves, using filters to block out particular wavelengths, allowing certain chemicals to stand out from their surroundings. The technique can detect blood diluted to as little as one part blood in 100 parts water. It can also distinguish between blood, bleach, rust and coffee.

Journal References:

1. Heather Brooke, Megan R. Baranowski, Jessica N. McCutcheon, Stephen L. Morgan, Michael L. Myrick. Multimode Imaging in the Thermal Infrared for Chemical Contrast Enhancement. Part 3: Visualizing Blood on Fabrics. Analytical Chemistry, 2010; 82 (20): 8427 DOI: 10.1021/ac101107v
2. Heather Brooke, Megan R. Baranowski, Jessica N. McCutcheon, Stephen L. Morgan, Michael L. Myrick. Multimode Imaging in the Thermal Infrared for Chemical Contrast Enhancement. Part 2: Simulation Driven Design. Analytical Chemistry, 2010; 82 (20): 8421 DOI: 10.1021/ac101108z
3. Heather Brooke, Megan R. Baranowski, Jessica N. McCutcheon, Stephen L. Morgan, Michael L. Myrick. Multimode Imaging in the Thermal Infrared for Chemical Contrast Enhancement. Part 1: Methodology. Analytical Chemistry, 2010; 82 (20): 8412 DOI: 10.1021/ac101109w

Further Reading
Functional Groups
Molecular Mass (Formula Weight)
Percent Composition (percentage composition)
Oxidation and Reduction
Energy Profiles and Catalysts
Parts per million concentration

Study Questions

1. Write the molecular formula for luminol given the structural formula shown in the article above.
2. Calculate the molecular mass (formula weight) of luminol.
3. Calculate the percentage of each element present in luminol.
4. Write a balanced chemical equation for the decomposition of hydrogen peroxide as described in the article.
5. The new thermal infrared technique can detect 1 part blood in 100 parts of water. Express this as a concentration in parts per million.
6. On the structure of luminol locate the following functional groups:
   • amine groups
   • double bond
   • carbonyl group
7. Luminol reacts with the hydroxide salt to form a dianion. Explain what is meant by the term dianion.
   
8. Explain how luminol could produce a dianion.
9. Do you think that crime scene investigators should use luminol to detect blood in commercial laundry? Explain your answer.
   
   

Carbon Dioxide and Climate Change

Scientists at Utrecht University, working with colleagues at the NIOZ Royal Netherlands Institute for Sea Research and the University of Southampton have been studying one of the hottest episodes of Earth's climate history, the Middle Eocene Climatic Optimum (MECO), which occurred around 40 million years ago in order to understand the relationship between Earth's climate and atmospheric carbon dioxide.

Algae use photosynthesis to harvest the energy of the sun, converting carbon dioxide and water into the organic molecules required for growth. Different isotopes of carbon are incorporated into these molecules depending on the environmental conditions under which algae grow. Ancient climate can therefore be reconstructed by analysing the carbon isotope ratios of molecules preserved in fossilised algae.

Using fossilised algae preserved in sediment cores extracted from the seafloor near Tasmania, Australia, by the Ocean Drilling Program, the scientists refined their estimates of carbon dioxide levels using information on the past marine ecosystem derived from studying changes in the abundance of different groups of fossil plankton.

Their analyses indicate that MECO carbon dioxide levels must have at least doubled over a period of around 400,000 years. In conjunction with these findings, analyses using two independent molecular proxies for sea surface temperature show that the climate warmed by between 4 and 6^oC over the same period, suggesting that increased amounts of carbon dioxide in the atmosphere played a major role in global warming during the MECO.

The rapid increase in atmospheric carbon dioxide levels around 40 million years ago approximately coincides with the rise of the Himalayas and may be related to the disappearance of an ocean between India and Asia as a result of plate tectonics, the large scale movements of the Earth's rocky shell (lithosphere).

References:

1. P. K. Bijl, A. J. P. Houben, S. Schouten, S. M. Bohaty, A. Sluijs, G.-J. Reichart, J. S. Sinninghe Damste, H. Brinkhuis. Transient Middle Eocene Atmospheric CO2 and Temperature Variations. Science, 2010; 330 (6005): 819 DOI: 10.1126/science.1193654
2. P. N. Pearson. Increased Atmospheric CO2 During the Middle Eocene. Science, 2010; 330 (6005): 763 DOI: 10.1126/science.1197894

Further Reading
http://www.ausetute.com.au/greenhouse.html
http://www.ausetute.com.au/ccycle.html
http://www.ausetute.com.au/carbon14.html
http://www.ausetute.com.au/isotopes.html

Study Questions

1. Write a chemical equation showing the conversion of atmospheric carbon dioxide into glucose by photosynthesis.
2. Explain what is meant by the term isotope.
3. Give the names and symbols of the three naturally occurring isotopes of carbon.
4. Which isotope of carbon is the most abundant?
5. Which isotopes of carbon are stable?
6. Which isotopes of carbon are unstable (radioactive)?
7. Write a nuclear decay equation for the unstable carbon isotope(s).
8. Explain how ancient climate can be reconstructed by analysing the carbon isotope ratios of molecules preserved in fossilised algae.

Carbon Capture and Storage (CCS)

Combustion of fossil fuels, such as coal, fuel oil, or natural gas, liberates large quantities of carbon dioxide, a gas that significantly affects global climate. A key technology that would reduce emissions and lead to more environmentally friendly power plants is the capture and storage of carbon dioxide from flue gases of power plants (carbon capture and storage (CCS)). CCS might be able to reduce CO₂ emissions resulting from the employment of fossil fuels for power generation and other uses in industry to near zero and thereby contribute to reducing greenhouse-gas emissions.
The Technische Universität Darmstadt has dedicated a pilot plant for capturing carbon dioxide contained in flue gases of power plants using two new methods:

• carbonate looping
• chemical looping

Carbonate looping involves utilizing naturally occurring limestone to initially bind CO₂ from the stream of flue gases transiting power plants' stacks in a first-stage reactor. The resultant pure CO₂ is re-liberated in a second reactor and can then be stored. The advantage of the carbonate-looping method is that even existing power plants can be retrofitted with this new method.

Chemical looping allows CO₂ to be captured with hardly any loss of energy efficiency. Under this method, a dual-stage, flameless, combustion yields a stream of exhaust gases containing only CO₂ and water vapor. The CO₂ can then be captured and stored.

Reference
Technische Universität Darmstadt (2010, November 7). On the way to CO₂-free power plants. ScienceDaily. Retrieved November 8, 2010, from http://www.sciencedaily.com­ /releases/2010/11/101103082306.htm

Further Reading
http://www.ausetute.com.au/combusta.html
http://www.ausetute.com.au/idealgas.html
http://www.ausetute.com.au/heatcomb.html
http://www.ausetute.com.au/greenhouse.html
http://www.ausetute.com.au/ccycle.html

Study Questions

1. Explain what is meant by the term fossil fuel.
2. Write a balanced chemical equation to represent the complete combustion of coal.
3. Write a balanced chemical equation to represent the complete combustion of natural gas.
4. If you burnt 1kg of coal and 1kg of natural gas, which reaction would produce the greatest amount of carbon dioxide?
5. If you burnt 1000cm³ of solid coal, and 1000cm³ of gaseous methane, which reaction would produce the greatest amount of gaseous carbon dioxide?
6. The heat of combustion of methane is 890 kJ/mol. Is energy released or absorbed during this reaction?
7. When coal burns it releases energy, about 250 kJ/mol. At 25^oC and 1 atmosphere pressure, is methane or coal the better fuel?
8. What benefits are there in storing the carbon dioxide emitted during power generation?
9. What disadvantages are there in storing carbon dioxide emitted during power generation?
10. What impact could the storage of this carbon dioxide have on the natural carbon cycle?
    

Organic Aqua Regia

While noble metals such as platinum and palladium are becoming increasingly important, the world has limited supplies of these metals so that it is vitally important that industry can recycle these metals efficiently.

Many of the transition metals have negative standard reduction potentials, indicating that these metals will dissolve in dilute acid, eg, clean chromium will dissolve in dilute hydrochloric acid

2 x [Cr(s) ----> Cr³⁺ + 3e] E^o = 0.74V
3 x [2e + 2H⁺ ----> H₂(g)] E^o = 0.00
_____________________________________________
2Cr(s) + 6H⁺ -----> 2Cr³⁺ + 3H₂(g) E^o = 0.74V

Some transition metals have positive reduction potentials, so they are poorer reducing agents than hydrogen, and are difficult to dissolve in acid. These metals are referred to as the noble metals and include silver, gold and platinum as well as ruthenium, rhodium, palladium, osmium, and iridium. Dissolving the noble metals requires the use of an oxidizing agent and sometimes a complexing agent. The most common reagent used to dissolve noble metals is aqua regia.

Aqua regia is a highly corrosive, fuming yellow or red solution formed when 1 part of concentrated nitric acid is added to 3 parts of concentrated hydrochloric acid. The nitric acid part is a powerful oxidizer, it oxidizers the noble metal atoms to cations. The hydrochloric acid provides a supply of chloride anions which react with the noble metal cations. For example, gold can be dissolved in aqua regia:

• gold reacts with nitric acid to form gold (III) ions:

Au(s) + 3NO₃^-(aq) + 6H⁺(aq) -----> Au³⁺(aq) + 3NO₂(g) + 3H₂O(l)

• gold (III) ions react with chloride ions to form chloroaurate anions:

Au³⁺(aq) + 4Cl^-(aq) -----> AuCl₄^-(aq)

However, aqua regia will dissolve all the metals together which introduces impurities into the recycling process. Georgia Institute of Technology scientists have developed a new organic solvent process that may solve this problem since the concentration of each component of the solvent can be adjusted to preferentially dissolve gold or palladium, but will not dissolve platinum. This solvent has been dubbed organic aqua regia.

Reference
Wei Lin, Rong-Wei Zhang, Seung-Soon Jang, Ching-Ping Wong, Jung-Il Hong. 'Organic Aqua Regia'-Powerful Liquids for Dissolving Noble Metals. Angewandte Chemie, 2010; 122 (43): 8101 DOI: 10.1002/ange.201001244

Further Reading
http://www.ausetute.com.au/acidbase.html
http://www.ausetute.com.au/trmetals.html
http://www.ausetute.com.au/ligands.html
http://www.ausetute.com.au/redox.html
http://www.ausetute.com.au/calcelemf.html

Study Questions

1. What is meant by the term transition metal?
2. What are the typical properties of a transition metal?
3. Refer to the equation above for the reaction between chromium and hydrochloric acid. Is this an example of a redox reaction? Explain your answer.
4. Refer to the equation above for the reaction between gold and nitric acid. Has the gold been oxidised or reduced? Explain your answer.
5. Refer to the equation above for the reaction between gold and nitric acid. Has nitrogen been oxidised or reduced? Explain your answer.
6. Could the reaction between gold and nitric acid be described as a redox reaction? Explain your answer.
7. Refer to the equation for the reaction between gold (III) ions and chloride ions. Is this a redox reaction? Explain your answer.
8. Write suitable equations for dissolving the following metals in aqua regia:

• iron
• tin
• copper
  
• silver
• platinum
• palladium