Lecture materials for the Introductory Chemistry course for Forensic Scientists, University of Lincoln, UK. See http://forensicchemistry.lincoln.ac.uk/ for more details.

1. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Organic Chemistry I University of Lincoln presentation

3. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Methane Neon Stable Octet required Covalent bonding – Atoms share electrons Carbon has 4 valence electrons Methane

5. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License 2s 2py 2px 2pz 4 x sp 3 C(6) – 1s 2 , 2s 2 , 2p x 1 , 2p y 1 , 2p z 0 C(6) – 1s 2 , 2s 1 , 2p x 1 , 2p y 1 , 2p z 1 Lowest energy state Excited state 4 sp 3

8. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Methane is Tetrahedral 109.5 o Sigma bonds formed by overlap of sp 3 and 1s orbitals Methane Sp 3 hybridized carbon 4 equivalent C-H bonds (s-bonds)

10. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Bonding in Ethylene

12. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License

13. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License sp-1s C-H Acetylene 2 sigma bonds and 2 pi bonds 180 o sp sp-sp, two 2p-2p C-C sp 2 -1s C-H Ethylene 3 sigma bonds and 1 pi bond 120 o sp 2 sp 2- sp 2, 2p - 2p C-C sp 3- 1s C-H Ethane 4 sigma bonds 109.5 o sp 3 sp 3 -sp 3 C-C Name Example Types of Bonds to Carbon Predicted Bond Angles Orbital Hybridisation Orbital overlap Bond

14. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Hydrocarbons Alcohols Amines Acids Ketones Aldehydes Amides Esters Ethers Nitrocompounds Halocarbons Nitriles Organic Compounds

15. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License HYDROCARBONS contain only C and H atoms ALIPHATIC hydrocarbons AROMATIC Hydrocarbons must contain a BENZENE ring UNSATURATED hydrocarbons contain at least 1 C–C multiple bond SATURATED hydrocarbons contain C–C and C–H single bonds only (ALKANES) ALKENE contains the C=C functional group ALKYNE contains the C ≡C functional group

17. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Properties of Alkanes (Solid) 343 37 C 20 H 42 Eicosane (Solid) 316 28 C 18 H 38 Octadecane 0.775 280 18 C 16 H 34 Hexadecane 0.763 254 6 C 14 H 30 Tetradecane 0.749 216 -10 C 12 H 26 Dodecane 0.730 174 -30 C 10 H 22 Decane 0.703 126 -57 C 8 H 18 Octane 0.684 98 -91 C 7 H 16 Heptane 0.659 69 -95 C 6 H 14 Hexane 0.626 36 -130 C 5 H 12 Pentane (Gas) 0 -138 C 4 H 10 Butane (Gas) -42 -188 C 3 H 8 Propane (Gas) -89 -172 C 2 H 6 Ethane (Gas) -162 -183 CH 4 Methane Density at 20 o C (g/mL) Boiling point ( o C) Melting point ( o C) Molecular formula Name

20. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License They all have different Physical Properties, Mpt, Bpt, densities 2, methylbutane Has the same molecular formula as n -pentane, C 5 H 12 2, 2 dimethylpropane C 4 H 10 – has two isomers, n -butane and isobutane (2-methylpropane) Isobutane Isopentane Neopentane

21. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Reactions of Alkanes ■ Combustion ■ Dehydrogenation ■ Halogenation alkene Ethane Bromoethane

22. IUPAC rules This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License The carbon chain is numbered from the end closest to the first additonal group. The additional groups are then named in alphabetical order irrespective of position number. 3-bromo-1-chlorobutane (not 1-chloro-3-bromobutane or 2-bromo-4-chlorobutane) Each addition to the carbon chain has its own number. The prefix di- inditcated there are two additional methyl groups. 2,2-dimethylbutane (not 2,2-methylbutane or 2-dimethylbutane) This is a saturated 6 carbon long chain with a methyl group attached to the third carbon. 3-methylhexane (not 2-ethylpentane or 4-methylhexane) The ending –ane means the C-C bonds are single. The Pent- tells us the longest chain is 5 carbons. They are numbered starting closest to the branch point. 2-methylpentane (not 4-methylpentane)

23. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License 2-Methylbutane Methyl (CH 3 CH 2 CH 2 CH 2 -) Butane Propyl (CH 3 CH 2 CH 2 -) Propane Ethyl (CH 3 CH 2 -) Ethane Methyl (CH 3 -) Methane Alkyl group Alkane

25. Reactions of Alkenes This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License ■ Addition reactions Alkyl Halides Alkyl hydrogen Sulphate Alcohols Dihaloalkanes

26. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License ■ Hydrogenation (another addition reaction) ■ Oxidation ■ Combustion Cyclohexene Cyclohexane

27. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Polymers are large molecules containing many identical repeating units (100-1000000) Polymerisation reaction is a repetition reaction which combines many small molecules of monomer (alkene) to form a polymer Addition polymer is a polymer in which the monomer simply add together with no other products formed besides polymer ■ Polymerisation ethylene polyethylene propylene polypropylene vinyl chloride poly(vinylchloride), PVC teflon Styrene polystyrene tetrafluoroethene

29. Reactions of Alkynes This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License ■ Combustion Alkynes are high energy compounds Welding gas ■ Addition reactions