Describe the structural formulae and reactions of compounds containing selected functional groups

1. Describe the structural formulae and reactions of compounds containing selected functional groups 4 credits

2. Selected organic functional groups are limited to: • Haloalkane • Alcohol • Alkene • Alkyne • Ester • Carboxylic acid Compounds are limited to: Those containing no more than 8 carbons. Larger organic molecules may be used in Qs linking structure & reactivity.

3. Naming compounds Knowledge of primary, secondary & tertiary alcohols & haloalkanes Structural and geometric isomers Distinguishing tests polymerisation Organic Chemistry Reactions of alkenes Elimination of water from alcohol H2/Pt Cl2 Acid reactions of carboxylic acid MnO4- Oxidation of primary alcohols to carboxylic acid Br2 H2O/H+ & HCl identify major & minor products Formation & hydrolysis of esters e.g. triglycerides Halogenation of alkanes

4. Fats, oils and soaps • Triglyceride is a fat that contains 3 ester links • Made from 3, long-chain carboxylic acids + glycerol (triol) • In the esterfication reaction, 3H20 is formed (OH from acid + H from glycerol)

5. Beware; they can change the orientation Divide between C and O, add Hs to form triol and OHs to form acid

6. Fats, oils and soaps Like all esters, triglycerides undergo hydrolysis. This reaction can be catalysed by either acid or base. • With acid • An acid catalyst is used (not conc. acid) to form glycerol (triol) and carboxylic acid again: 2.With alkali (OH-) If NaOH is used, it reacts with the carboxylic acid to form a sodium salt and glycerol. The sodium salt in this case is called ‘soap’ and the reaction is called ‘saponification’

7. Acid conditions: glycerol and palmitic acid formed. Alkali conditions: glycerol and the sodium salt of palmitic acid formed

8. Notice there are 3 diff. acids

9. In basic conditions: glycerol would still form but instead of the acid a sodium salt would form.

10. Na

11. Polymerisation • A polymer is a large molecule made of small molecules called monomers • In addition polymerisation, nothing else is made • All monomers are alkenes • Could be asked to draw monomers from polymers or vice versa

12. OH CH=CH2 Isolate 2 carbons to form the basis of the alkene monomer Break the double bond, attach to next monomer

13. Isolate 2 carbons, straighten them and put the double bond in

14. Naming compounds Learn functional groups and endings!

15. Crocodiles! What is eaten first is named first! 1-chloropropane Numbering begins at ene end methylpropanoate -anoic grp is always on carbon 1

16. Structural isomers Same number of atoms in a different arrangement Geometric isomers • Different arrangements of atoms in space • Cis (same side) & trans (across) • Due to double bond being unable to rotate • Can have different properties e.g. polarity & boiling point

17. Don’t need to give number placing for methyl and ene. They can be nowhere else! methylpropene cyclobutane

18. But-1-ene But-2-ene Cannot form cis & trans because the groups on each C are not different Can form cis & trans because the groups on each C are different and the double bond doesn’t allow rotation Base the drawing around the double bond to examine the groups Remember this! It’s the stock answer for explaining geometric isomers

19. Reactions of alkenes All types of addition reactions Watch out for Markovnikov’s! Asymmetrical alkene = 2 products Watch out for Markovnikov’s! Asymmetrical alkene = 2 products

20. Primary, secondary & tertiary • Classifications in alcohols and haloalkanes • Look at the Carbon the alcohol/halogen is attached to. Is this attached to 1, 2 or 3 carbons? • Form straight line (!), T-shape or cross

21. primary secondary primary tertiary

22. Reactions of alcohols • Elimination of water (dehydration): • alcohol  Alkene + water • Oxidation of 1° alcohol: • 1° alcohol  (aldehyde)  Carboxylic acid • Can use H+/MnO4- as oxidising agent instead. Purple to colourless • Esterfication: • alcohol + Carboxylic acid  ester Conc. H2SO4 H+/Cr2O72- Dichromate turns from orange to green Conc. H2SO4

23. This is a dehydration reaction (elimination) Alcohol + acid…

24. Oxidation of a primary alcohol… Potassium permanganate will turn from purple to colourless

25. Reactions of carboxylic acids • Normal acid reaction e.g. fizzing with metal  H2 & fizzing with carbonates  CO2 & litmus turning red • Form metal salts involving the organic acid e.g. sodium methanoate • Form esters when reacted with alcohols

26. Distinguishing tests

27. Acidified potassium dichromate (H+/Cr2O72-) Propan-1-ol will turn acidified potassium dichromate from orange to green. Propanoic acid will remain orange. There are other possible answers, see how many you can come up with!

28. hexane hex-1-ene Decolourises bromine slowly with UV light Decolourises bromine quickly Saturated so undergoes a substitution reaction unsaturated so undergoes an addition reaction Forms 1-bromohexane Forms 1,2-dibromohexane CH3CH2CH2CH2CH2CH3 + Br2 CH2BrCH2CH2CH2CH2CH3 + HBr CH2CHCH2CH2CH2CH3 + Br2 CH2BrCBrCH2CH2CH2CH3 + HBr

29. Adding water to an asymmetric alkene…but which product goes where? So B must be a primary alcohol and reagent D must be an oxidant End product = ester. Reagent = alcohol. So C must be… Propan-2-ol Propan-1-ol H+/Cr2O72- To form a sodium salt of an ester… NaOH Propanoic acid