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The Organic Chemical Industry

Murray Low & Udhir Chathuri. The Organic Chemical Industry. Natural Gas. Overview. Crude oil. Propylene. Natural Resources. Ethylene. Gasification. Coal. Chemicals from oil. Cracking. Fischer- Tropsch. Elements. Quiz A. Reforming. Liquefaction. Raw Materials. Processes.

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The Organic Chemical Industry

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  1. Murray Low & UdhirChathuri The Organic Chemical Industry

  2. Natural Gas Overview Crude oil Propylene Natural Resources Ethylene Gasification Coal Chemicals from oil Cracking Fischer- Tropsch Elements Quiz A Reforming Liquefaction Raw Materials Processes The Organic Chemical Industry Condensation Polymers Addition Polymers Step Growth Quiz C Chain Growth Quiz B Recycling Common Condensation Polymers Natural Polymers Typical Synthesis Elasticity Common Addition Polymers Synthetic Polymers PES Addition Polymers Condensation Polymers LDPE vs. HDPE PI PA Polyester LDPE PE Polyamide Physical Prop. PTFE PS PC PMM PVC

  3. Raw Materials Raw Materials for Organic chemicals must contain……

  4. Coal Raw Materials Value Added Polystyrene

  5. Raw Materials Crude Oil Octane Value Added Ethylene Polyethylene

  6. Raw Materials Natural Gas CH4 + CO H2 Value Added Alcohol Detergent

  7. Petroleum, Crude Pet Coal C SA’s Natural Resources Crude import Oil Rig Platinum Pt C Gold C P Diamond Pt Pt Iron ore & steel Pt Pt Salt Secunda Sasolburg Copper LimeS Clays Ti Gypsum Zn C C export Pb Cement Pet Limestone Lime Sulfur LimeS S LimeS Phosphate P LimeS Pig iron Pig P Pet Titanium Ti LimeS Zinc Pet Zn Pig Lead Pb

  8. Gases C2–C4 Chemicals from oil Light naphtha C5–C9 Catalytic Cracking & Reforming Heavy naphtha C7–C9 Chemicals Crude Oil Atmospheric Distillation Column Petrol C5–C12 Diesel fuel C10–C15 Atmospheric gas oil Paraffin C12–C15 Heavy Fractions Vacuum gas oil Lubricating Oils Asphalt Residual or heavy fuel oil Vacuum Distillation Column Lubricating oil feeds Heavy gas oil Pitch

  9. Quiz A- Resources 1. Consider the following tables outlining the known resources and the estimated consumption(2005) of oil, coal and gas.

  10. Quiz A- Resources What % of the world’s oil, coal & gas reserves are in Africa? What % of the world’s population resides in Africa? What % of the world’s consumption of oil, coal & gas (separately) did Africa use in 2005? Based on 2005 figures, how many years supply of each of the fossil fuels is left? i) For the world ii) For Africa (assuming Africa uses it own natural resources) e) The fossil fuel reserves of the planet are mainly used for energy. Presently over 80% of the world’s energy supply comes from oil, coal & gas. 47% of the world’s oil supply, which is the highest contributor to energy needs(36% of the global total), has already been exhausted. What problems do you foresee for the organic chemical industry over the next 40 years?

  11. Gases C2–C4 Chemicals from oil Light naphtha C5–C9 Catalytic Cracking & Reforming Heavy naphtha C7–C9 Chemicals Crude Oil Atmospheric Distillation Column Petrol C5–C12 Diesel fuel C10–C15 Atmospheric gas oil Paraffin C12–C15 Heavy Fractions Vacuum gas oil Lubricating Oils Asphalt Residual or heavy fuel oil Vacuum Distillation Column Lubricating oil feeds Heavy gas oil Pitch

  12. Reforming Rearrangement of atoms within the molecule. The carbon number is usually maintained.

  13. Cracking The process of breaking large organic molecules into smaller compounds by breaking existing C - C bonds . Δ Large molecules Small molecules ΔH = +ve 850oC e.g. C12 C8 C4

  14. Cracking The Holy Grail in organic industrial chemistry is to get to the starting materials for polymers : ethene(ethylene) & propene(propylene) via cracking of larger molecules. Δ C8H16 C2H4 + 2C3H6 e.g. catalyst Why?

  15. Acetaldehyde Commodity chemicals • Ethyl benzene • Ethylene oxide • Ethylene • Polyvinylacetate • Adhesives • n-butyl alcohol • 2-ethylhexanol • Non-ionic detergents • ethanolamines • Glycol ethers • glyoxal • Vinyl chloride • trichloroethylene • perchloroethylene • Plastics • Synthetic rubber • Ethylene • dichloride • LDPE • HDPE • E.P rubbers • (with propylene) • Vinyl • acetate * * See Pg 51 for detailed diagram(click here)

  16. Phenol & • Acetone Commodity chemicals • Polypropylene • E.P rubber • (with ethylene) • Acrylonitrile • Propylene • Paint remover • Acrylic fibres • Acrylic acid • Polyglycols • Nitrilefibres • Propylene • glycol • glycerine • Polyethers • Resins • Resins • Allyl • chloride • Propylene • Chlorohydrin * • Acrolein * See Pg 52 for detailed diagram(click here)

  17. Gasification - Sasol Sasol employs the gasification of coal as their carbon feedstock. 4CH + O2 + 3H2O 3CO + CO2 + 5H2 Coal Oxygen Steam Synthesis gas Synthesis gas or Syn Gas is simply a mixture of various ratios of carbon monoxide and hydrogen with some carbon dioxide. The exact ratio will depend upon the C : H ratio in the coal.

  18. Fischer- Tropsch The Syn Gas is employed by Sasol in what is known as the Fischer-Tropsch process. This process builds carbon chains from the carbon monoxide feedstock through a methanol intermediate. CO + 2H2 CH3OH CO2 + 3H2 CH3OH + H2O CH3OH + nCO + 2nH2 CH3(CH2)nOH + nH2O e.g. for n = 8 CH3OH + 8CO + 16H2 CH3(CH2)8OH + 8H2O The alcohols can be dehydrated to form alkenes: -H2O CH3(CH2)8OH CH3(CH2)6CHCH2 and then the alkenes can be hydrogenated to form alkanes: CH3(CH2)6CHCH2 + H2 CH3(CH2)7CH3

  19. Liquefaction Benzene Toluene Naphthalene Xylenes Quinoline Phenols Pyridine Cresols This is an energy intensive process as we are breaking C – C bonds.

  20. Polymers Poly Mers “Many” “Parts” Addition Polymers Condensation Polymers

  21. Addition Polymers(Chain Growth) + + + + Monomer Tetramer Dimer Trimer Monomer Monomer Monomer Monomer Pentamer Dimer Trimer Tetramer ( n = 4) ( n = 2) ( n = 5) ( n = 3) ………… ………… ………… Polymer ( n = 10 000 – 100 000) Mw = ~ 106

  22. Natural Polymers The size of natural polymers is templated. For example protein synthesis is ultimately controlled by DNA. The result of this is that the same molecule arises every time. n (the number of monomer units in the polymer chain) is a constant. Mass Distribution of a natural polymer : No. of molecules 0 n

  23. Synthetic Polymers Synthetic polymers differ from natural polymers in that synthetic polymers contain a range of chain lengths i.e. n is not a single number. Mass Distribution of a synthetic polymer : No. of molecules 0 n

  24. Addition Addition Polymers Alkenes Polymer Chain R R R R R R R R R R R R R R R R R R C C C C C C C C C C C C C C C C C C R R R R R R R R R R R R R R R R R R The identity of R largely determines the properties of the polymer. R could be H, Cl, F, Phenyl or a combination of these or ANY other groups. The mechanism of polymerisation is independent of the identity of R.

  25. Common Addition Polymers http://seminar.unipack.ru/eng/2007/2/

  26. Common Addition Polymers http://www.au.fjfdi.com/en/cn/project.asp?job=showen&id=8293&yuyan=en

  27. Common Addition Polymers http://archive.greenpeace.org/toxics/html/content/pvc2.html

  28. Common Addition Polymers http://en.wikipedia.org/wiki/Methyl_methacrylate

  29. Common Addition Polymers http://www.fluon.jp/fluon/english/about/qa/index_1.shtml

  30. Common Addition Polymers http://www.rsc.org/ej/NP/2001/A902191D/

  31. Common Addition Polymers – Typical Synthesis Initiation R R R R R O O O O O O R Organic peroxide Homolytic fission Propagation H H H H H H C C C C C C Cl Cl Cl Cl Cl Cl Cl Cl Cl H H H H H H H H H H H H H H H C C C C C C C C C C C C H H H H H H n

  32. Common Addition Polymers – Typical Synthesis Termination R R R R O O O O Combination Cl Cl Cl Cl Cl Cl Cl Cl Disproportionation Cl Cl Cl Cl H H H H H H H H H H H H H H H H H H H H H H H H C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H

  33. Quiz B- Addition Polymers 1. Polystyrene is prepared from the monomer styrene shown below. Styrene Benzoylperoxide is used as the initiator Benzoylperoxide 1 mole of benzoylperoxide loses 2 moles of CO2 upon breaking of the peroxide bond leading to 2 phenyl radicals which act as the initiator.

  34. Quiz B- Addition Polymers Write down a balanced chemical equation for the formation of phenyl radicals from benzoylperoxide. Show the activation step for the reaction of a phenyl radical with the monomer styrene. Draw a reaction scheme for the first 2 propagation steps in the formation of a polystyrene chain. Draw a reaction scheme for two possible routes of chain termination.

  35. Quiz B- Addition Polymers 2. 2-2´-azo-bis-isobutyrolnitrile (AIBN) is a common initiator in free radical polymerisation. It thermally decomposes to release nitrogen gas and free radicals. Draw a mechanism for the decomposition of AIBN. Draw the mechanism of the initiation step of forming a reactive chain growth centre by reacting the radical from AIBN with vinyl chloride. Draw the mechanism of the first 2 steps of the propagation of the chain. Draw the mechanism of 2 possible chain termination steps.

  36. Condensation Polymers (Step-Growth Polymers) Addition polymers ………… Condensation polymers …………

  37. Common Condensation Polymers http://www.prlog.org/10009259-polyester-production-to-grow-at-4-rate-in-the-next-5-yrs.html

  38. Common Condensation Polymers Industrial Organic Chemistry: Important Raw Materials and Intermediates By Klaus Weissermel, Hans-JürgenArpe

  39. Common Condensation Polymers http://goliath.ecnext.com/coms2/gi_0199-1790647/Bright-prospect-for-the-polycarbonate.html

  40. Condensation Polymers In condensation polymers two different ‘monomers’ are present. Each of the ‘monomers’ has two functional groups. 1 + Polyester 1 3 H H 2 + O O C H C H H Polyamide H H 2 3 O H O N N C H H C C C H H H 6 O O H H H 4 3

  41. Condensation Polymers - Polyester O H O O H O O O O H H H O O O O H O C C C C C C C C C C C C C C C H H H H H H H H H H H H C C C O O O O H H H H H H H H H H H 4 O H 4 H H H H 4 4 4 O O O O O O O O O O O O C C C C C C C C C C C C H H H H H H H O O O O O O H 4 H H H H C C C C C C H H H H H H H H H H H H H H H H O O O O C C C C H H H H H H H H H H O O H H O O H H H H C C C C C C O O O O H H H H H H 4 4

  42. Condensation Polymers - Polyamide O O H H O O O H O O O H H O O C C C C C C O O H H O O C C C C C C C C C H O O O H H H H H 4 4 C C C C C C H H O O O O H H H H N N C H H 4 H H 4 4 H O O H H H N N N N C C H H H H H H 4 4 H H H 6 N N C H H H H N N C H H 6 6 H H H H H 6 H 6 H H H H H H O O H H O O N N N N C C C C C C C C H H H H H H 6 6 O O O O H H H H H H 4 4

  43. Physical Properties Q Why do polymers have the physical properties they do? A Mainly its due to the fact that they are BIG MOLECULES! It is the interactions between the chains that are important.

  44. Physical Properties - LDPE One would expect free-radical polymerization to result in linear polymer chains……………… H C NOT SO Back - Biting H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H C C H R R R O O O C C C C C C C C C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H H H H H H H H H H H H H C C4 branch H C C H H H H H H C C H

  45. Physical Properties – LDPE vs. HDPE LDPE – branched molecules HDPE- linear molecules Less dense due to limited packing. Not synthesized via radical polymerization. Very dense due to closer packing.

  46. Physical Properties - Elasticity Q Why do some polymers stretch irreversibly and why are some polymers rubbery? Easily pulled apart - stretchy High density of crosslinks – rigid, non-elastic Crosslink between chains Chains can move but crosslinks pull them back together Network Polymer

  47. Physical Properties

  48. Quiz C- Condensation Polymers Which graph best describes condensation polymerisation and which graph best describes addition polymerisation? Explain your answer. [Monomer] A B 0 time

  49. Quiz C- Condensation Polymers Poly(ethylene terephthalate), PET, is widely used to make synthetic fibres and plastic bottles for beverages. It is prepared from a polycondensation of a di-ol and a di-carboxylic acid. Given the structure of PET shown below, write down the chemical structure and the names of both monomers. Polyurethanes can be prepared from the reaction of diisocyanates and a diol. An isocyanate has the functional group and a urethane linkage is This is a strange reaction in that it is not a condensation – no small molecule is excluded in the reaction. Draw the repeat unit of the polymer arising from the reaction of the 1,4-butanediol with 1,6-hexanediisocyanate.

  50. Quiz C- Polymers + 4. Polyisoprene is an important synthetic rubber. It is prepared from the monomer 2-methyl-1,3-butadiene. Most rubbers are prepared from conjugated dienes. Once the main chain is formed the presence of a single double bond in the repeat unit gives rise to the possibility of crosslinking through the process of vulcanisation. 2 main possibilities of polymerization exist. The first gives rise to a trans-but-2-ene repeat unit and the other a cis-but-2-ene repeat unit. Draw the structure of the monomer. Draw the structure of the trans-but-2-ene repeat unit. Draw the structure of the cis-but-2-ene repeat unit. Would you expect that rubbers have a low, medium or high density of crosslinks?

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