To get reactivity out of an organic molecule, functional groups have to be added.

1. Functional Groups • To get reactivity out of an organic molecule, functional groups have to be added. • Functional groups control how a molecule functions. • More complicated functional groups contain elements other than C or H (heteroatoms). • Functional group containing molecules can either be saturated (alcohols, ethers, amines etc.) or unsaturated (carboxylic acids, esters, amides, etc.). • We usually use R to represent alkyl groups.

4. Alcohols • The functional group of an alcohol is an -OH group bonded to an sp3 hybridized carbon • bond angles about the hydroxyl oxygen atom are approximately 109.5° • Oxygen is sp3 hybridized • two sp3 hybrid orbitals form sigma bonds to carbon and hydrogen • the remaining two sp3 hybrid orbitals each contain an unshared pair of electrons

5. Nomenclature-Alcohols • IUPAC names • the parent chain is the longest chain that contains the OH group • number the parent chain to give the OH group the lowest possible number • change the suffix -e to -ol • Common names • name the alkyl group bonded to oxygen followed by the word alcohol

6. Nomenclature-Alcohols • Examples

7. C H C H C H C H C H C H C H C H 3 2 2 2 2 2 H O O H O H O H H O H O O H 1,2-Ethanediol 1,2-Propanediol 1,2,3-Propanetriol (Ethylene glycol) (Propylene glycol) (Glycerol, Glycerine) Nomenclature of Alcohols • Compounds containing more than one OH group are named diols, triols, etc.

8. Nomenclature of Alcohols • Unsaturated alcohols • show the double bond by changing the infix from -an- to -en- • show the the OH group by the suffix -ol • number the chain to give OH the lower number

9. Physical Properties • Alcohols are polar compounds • they interact with themselves and with other polar compounds by dipole-dipole interactions • Dipole-dipole interaction:the attraction between the positive end of one dipole and the negative end of another

10. Physical Properties • Hydrogen bonding:when the positive end of one dipole is an H bonded to F, O, or N (atoms of high electronegativity) and the other end is F, O, or N • the strength of hydrogen bonding in water is approximately 21 kJ (5 kcal)/mol • hydrogen bonds are considerably weaker than covalent bonds • nonetheless, they can have a significant effect on physical properties

11. Hydrogen Bonding

12. Physical Properties • In relation to alkanes of comparable size and molecular weight, alcohols • have higher boiling points • are more soluble in water • The presence of additional -OH groups in a molecule further increases solubility in water and boiling point

13. Physical Properties

14. Phenols • Alcohol with aromatic ring

15. Phenols

16. Phenols • Ingredients in cloves, vanillia, nutmeg, mint

17. Thiols: Structure • The functional group of a thiol is an SH (sulfhydryl) group bonded to an sp3 hybridized carbon • The bond angle about sulfur in methanethiol is 100.3°, which indicates that there is considerably more p character to the bonding orbitals of divalent sulfur than there is to oxygen

18. Nomenclature • IUPAC names: • the parent is the longest chain that contains the -SH group • change the suffix -e to -thiol • when -SH is a substituent, it is named as a sulfanyl group • Common names: • name the alkyl group bonded to sulfur followed by the word mercaptan

19. bp (° C) bp (° C) M ethanethiol M ethanol E thanethiol E thanol Thiols: Physical Properties • Because of the low polarity of the S-H bond, thiols show little association by hydrogen bonding • they have lower boiling points and are less soluble in water than alcohols of comparable MW • the boiling points of ethanethiol and its constitutional isomer dimethyl sulfide are almost identical Thiol Alcohol 65 6 78 35 1-Butanethiol 1-Butanol 117 98

20. Thiols: Physical Properties • Low-molecular-weight thiols = STENCH • the scent of skunks is due primarily to these two thiols • a blend of low-molecular weight thiols is added to natural gas as an odorant; the two most common of these are

21. Ethers (R-O-R′) • Compounds in which two hydrocarbons linked by an oxygen are called ethers. • Ethers are commonly used as solvents.

22. C H O H 3 C H O C C H C H C H O C H C H 3 3 3 2 2 3 C H O C H C H 3 2 3 Ethoxyethane trans- 2-Ethoxy- 2-Methoxy-2- (Diethyl ether) methylpropane cyclohexanol ( tert- Butyl methyl ether) Nomenclature: ethers • IUPAC: the longest carbon chain is the parent • name the OR group as an alkoxy substituent • Common names: name the groups bonded to oxygen in alphabetical order followed by the word ether

23. Nomenclature: ethers • Although cyclic ethers have IUPAC names, their common names are more widely used • IUPAC: prefix ox- shows oxygen in the ring • the suffixes -irane, -etane, -olane, and -ane show three, four, five, and six atoms in a saturated ring

24. Physical Properties • Although ethers are polar compounds, only weak dipole-dipole attractive forces exist between their molecules in the pure liquid state

25. C H C H O H C H O C H 3 2 3 3 bp 78° C Physical Properties • Ethanol and dimethyl ether are constitutional isomers. • Their boiling points are dramatically different • ethanol forms intermolecular hydrogen bonds which increase attractive forces between its molecules resulting in a higher boiling point • there is no comparable attractive force between molecules of dimethyl ether Dimethyl ether Ethanol bp -24°C

26. Physical Properties • Boiling points of ethers are • lower than alcohols of comparable MW • close to those of hydrocarbons of comparable MW • Ethers are hydrogen bond acceptors • they are more soluble in H2O than are hydrocarbons

27. C H H C 3 H C C H 3 2 2 Oxirane cis- 2,3-Dimethyloxirane 1,2-Epoxycyclohexane C l C l (Ethylene oxide) ( cis- 2-Butene oxide) (Cyclohexene oxide) Epoxides • Epoxide: a cyclic ether in which oxygen is one atom of a three-membered ring • simple epoxides are named as derivatives of oxirane • where the epoxide is part of another ring system, it is shown by the prefix epoxy- • common names are derived from the name of the alkene from which the epoxide is formally derived H H 1 H 2 3 O C C O O 2 1 H O epichlorohydrine

28. Crown Ethers • Crown ether:a cyclic polyether derived from ethylene glycol or a substituted ethylene glycol • the parent name is crown, preceded by a number describing the size of the ring and followed by the number of oxygen atoms in the ring

29. Crown Ethers • The diameter of the cavity created by the repeating oxygen atoms is comparable to the diameter of alkali metal cations • 18-crown-6 provides very effective solvation for K+

30. Thioethers • The sulfur analog of an ether • IUPAC name: select the longest carbon chain as the parent and name the sulfur-containing substituent as an alkylsulfanyl group • common name: list the groups bonded to sulfur followed by the word sulfide

31. Disulfide • Disulfide: contains an -S-S- group • IUPAC name: select the longest carbon chain as the parent and name the disulfide-containing substituent as an alkyldisulfanyl group • Common name: list the groups bonded to sulfur and add the word disulfide

32. Silyl Ethers

33. Compounds with a Carbonyl Group • Carboxylic Acids • Carboxylic acids contain a carbonyl group with an -OH attached. • The carboxyl functional group is -COOH: • Carboxylic acids are weak acids. • Named like alkanes with “-oic acid” at the end. • Typical carboxylic acids are found in spinach, vinegar, cleaners, vitamin C, aspirin, and citrus fruits. • Carboxylic acids are also used to make polymers for fibers, paints, and films.

34. Structure • The functional group of a carboxylic acid is a carboxyl group • the general formula for an aliphatic carboxylic acid is RCOOH; that for an aromatic carboxylic acid is ArCOOH

35. Nomenclature - IUPAC • IUPAC names: drop the -e from the parent alkane and add the suffix -oic acid • if the compound contains a carbon-carbon double bond, change the infix -an- to -en-

36. Nomenclature - IUPAC • The carboxyl group takes precedence over most other functional groups

37. Nomenclature - IUPAC • dicarboxylic acids: add the suffix -dioic acid to the name of the parent alkane containing both carboxyl groups

38. Nomenclature - IUPAC • if the carboxyl group is bonded to a ring, name the ring compound and add the suffix -carboxylic acid • benzoic acid is the simplest aromatic carboxylic acid • use numbers to show the location of substituents

39. Nomenclature-Common • when common names are used, the letters etc. are often used to locate substituents

40. Physical Properties • In the liquid and solid states, carboxylic acids are associated by hydrogen bonding into dimeric structures

41. Physical Properties • Carboxylic acids have significantly higher boiling points than other types of organic compounds of comparable molecular weight • they are polar compounds and form very strong intermolecular hydrogen bonds • Carboxylic acids are more soluble in water than alcohols, ethers, aldehydes, and ketones of comparable molecular weight • they form hydrogen bonds with water molecules through their C=O and OH groups

42. Physical Properties • Table 17.2

43. Physical Properties • water solubility decreases as the relative size of the hydrophobic portion of the molecule increases

44. EXERCICES

45. Compounds with a Carbonyl Group • Aldehydes and Ketones • The carbonyl functional group is C=O. • Aldehydes must have at least one H atom attached to the carbonyl group: • Ketones must have two C atoms attached to the carbonyl group: • Aldehydes and ketones are prepared from the oxidation of alcohols.

46. H C H C H C H C H C C H 3 3 3 Methanal Ethanal Propanone (Formaldehyde) (Acetaldehyde) (Acetone) Structure • the functional group of an aldehyde is a carbonyl group bonded to a H atom and a carbon atom • the functional group of a ketone is a carbonyl group bonded to two carbon atoms O O O

47. Nomenclature • IUPAC names: • the parent chain is the longest chain that contains the functional group • for an aldehyde, change the suffix from -e to -al • for an unsaturated aldehyde, change the infix from -an- to -en-; the location of the suffix determines the numbering pattern • for a cyclic molecule in which -CHO is bonded to the ring, add the suffix -carbaldehyde

48. Nomenclature: Aldehydes • the IUPAC retains the common names benzaldehyde and cinnamaldehyde, as well formaldehyde and acetaldehyde

49. Nomenclature: Ketones • IUPAC names • the parent alkane is the longest chain that contains the carbonyl group • indicate the ketone by changing the suffix -e to -one • number the chain to give C=O the smaller number • the IUPAC retains the common names acetone, acetophenone, and benzophenone

50. Common Names • for an aldehyde, the common name is derived from the common name of the corresponding carboxylic acid • for a ketone, name the two alkyl or aryl groups bonded to the carbonyl carbon and add the word ketone