Organic Compounds containing Oxygen, Halogen, or Sulfur

1. Organic Compounds containing Oxygen, Halogen, or Sulfur

2. Alcohols, Ethers, Alkyl Halides & Thiols • ROH • ROR • RX • RSH • All of these compounds contain a carbon atom that is singly bonded to a heteroatom (other than H or C)! • Alcohols & ethers can be considered organic derivatives of water • Replacing H(s) with one or two alkyl groups • HOH; ROH; ROR

3. Alcohols • Structural Characteristics • R-OH -OH (hydroxyl = functional group) -OH is bonded to a saturated C atom! • Classification • Primary (1˚) C-C-OH • Secondary (2˚) C-C-OH | C • Tertiary (3˚) C | C-C-OH | C

4. Alcohol Nomenclature • IUPAC • Name the longest chain (drop the “e” and add “ol” at the end) to which -OH is attached. • # the chain from the end nearest the -OH* (# the position of the -OH group). • Name/locate any substituents. • For rings, -OH is on C#1.

5. IUPAC naming examples l • Ex.: CH3OH Methanol • CH3CH2CH2OH 1-propanol • CH3CHCH3 | OH 2-propanol 3,4-dimethylcyclohexanol • Alcohols with >1 -OH groups • Ex.: CH2CH2 | | 1,2-ethanediol OH OH

6. Alcohol Nomenclature • Common (name “R” as an alkyl group) • Alkyl group name + alcohol • Ex.: CH3OH Methyl alcohol • CH3CHCH3 | Isopropyl alcohol OH • Alcohols with >1 -OH groups • Ex.:

7. IUPAC Methanol Ethanol 2-propanol 1,2-ethanediol 1,2-propanediol 1,2,3-propanetriol Common Methyl alcohol Ethyl alcohol Isopropyl alcohol Ethylene glycol Propylene glycol Glycerol (glycerin) Important Common Alcohols For survival in northern winters, many fish and insects produce large amounts of glycerol that dissolve in their blood, thereby lowering the freezing point.

8. How does % relate to “proof”?

9. Constitutional Isomerism • Positional • Ex.: butanol 1-butanol 2-butanol • Skeletal • Ex.: butanol 2-butanol sec-butyl alcohol 2-methyl-2-propanol tert-butyl alcohol

10. Physical Properties of Alcohols • Alcohols have both Polar & Nonpolar character! (-OH) (alkyl) • Properties are determined by which portion dominates • Short chain (<6) - polar end dominates • Long chain (6+) - nonpolar end dominates • BP increases with increasing # of C atoms • Effect of London Dispersion Forces • Water solubility • Short chain - soluble • Long chain - insoluble • Alcohols can Hydrogen bond • (better with small chain alcohols) • affects BP & Solubility in Water • Alkanes cannot Hydrogen bond

11. (a) The polar hydroxyl functional group dominates the physical properties of methanol. • (b) Conversely, the nonpolar portion of 1- octanol dominates its physical properties.

13. Chemical Reactions of Alcohols • Combustion • CH3OH + O2 --> CO2 + H2O • Two types of Dehydration! • Intramolecular Alcohol dehydration • Conditions: 180˚C and H2SO4 catalyst • Result: formation of alkene (elimination/condensation rxn) • Ex.: C-C-OH ----> C=C + H2O • Ex.: 2-butanol --> • Zaitsev’s rule: major product is alkene w/ greatest # of alkyl groups

14. Chemical Reactions of Alcohols • Intermolecular Alcohol dehydration • Conditions: 140˚C (lower temp!) and H2SO4 catalyst • Result: formation of ether (R-O-R) (condensation rxn) • Ex.: C-OH + HO-C ----> C-O-C + H2O

15. Halogenation Reactions • R-C-OH + X2 ----> R-C-X2 + H2O • Not a particularly common reaction, however

16. Oxidation Reactions • Oxidation results in an increase in the number of C-O bonds or a decrease in the number of C-H bonds. • 1˚ alcohol ---> aldehyde ---> carboxylic acid • 2˚ alcohol ---> ketone • 3˚ alcohol ---> No Reaction! The oxidation of ethanol is the basis for the “breathalyzer test.”

17. Preparation of Alcohols • Alcohols can be prepared in two major ways: • Alkene hydration • Ex.: CH2=CH2 + H2O ----> CH3CH2OH • Addition of H2 to a carbonyl group (-C=O) • Ex.: Aldehyde + H2 ----> 1˚ alcohol Ketone + H2 ----> 2˚ alcohol

18. Phenols • Structural Characteristics • -OH is attached to a C that is part of an aromatic ring. • Ar-OH

19. Nomenclature of Phenols • Phenol= “phenyl” + “alcohol” • IUPAC rules are same as for benzene derivatives. Parent ring is “phenol”. • Ex.:

20. Physical & Chemical Properties of Phenols • Flammable, like alcohols • Phenols cannot be dehydrated. • Oxidation occurs only with strong oxidizing agents. • Halogenation • Weak acids in solution (Ka~10-10)

21. Occurance & Uses of Phenols Many commercially baked goods contain the antioxidants BHA and BHT to help prevent spoilage. • Antiseptics (but phenol derivatives are much safer than phenol itself). • Mouthwashes, Lysol, etc. • Antioxidant - several phenols are preferentially oxidized • Food additives • Vit. E • Flavoring agents • Irritants: poison ivy & poison oak Nutmeg tree fruit. A phenolic compound, isoeugenol, is responsible for the odor associated with nutmeg.

22. Ethers • Structural Characteristics • Functional group = -C-O-C- • Remember ascorbic acid? • R-O-R • R-O-R’ • R-O-Ar • Ar-O-Ar

23. IUPAC Select longest C chain = base name. Change -yl ending of other group to -oxy. (ie. Methyl becomes methoxy) Place alkoxy name (w/ locator #) in front of base chain name Ex.: C-C-O-C-C-C-C Common Name the two alkyl groups (alpha order) attached to the O and add the word “ether”. Nomenclature of Ethers

24. Examples:

25. Consitutional Partitioning of C atoms (by O) - positional! Isomers of individual alkyl groups Ex.: C4 ethers Functional Group Isomers (1st time we encounter this possibility) Consitutional isomers with different functional groups Ex.: C3 ether and C3 alcohol Isomerism

26. Physical BP = to alkanes; lower than alcohols No H-bonding w/ self possible Water soluble Can H-bond w/ water NP substances are generally soluble in ethers Act as anesthetics Diethyl ether Chemical Flammable React w/ O2 to form unstable (explosive) ccompounds Unreactive w/ acids and oxidizing agents Halogenation Prepared by intermolecular dehydration of 1˚ alcohols Physical & Chemical Properties

27. Alkyl Halides:Incoming halogen atom (orange sphere) replaces a hydrogen atom in the alkane model. • Naming: • Treat halogen atoms like alkyl groups. • F = fluoro; Cl = chloro; Br = bromo; I = iodo • Ex.: CH3-CHBr-CHBr-CHI-CH2-CH3

28. Halogenation Reactions General equation: RH + X2→ RX + HX Hydrocarbon + Halogen  Halogenated + acid (diatomic) hydrocarbon Ex. CH4 + Cl2 --> CH3Cl + HCl Highly exothermic reaction: can lead to an explosion

29. The process can continue to alter the resulting products as long as the halogen remains in sufficient quantities to drive further reactions. (The halogen would be the __________ reactant.)

30. Space-filling models of the four ethyl halides. Do these molecules act as polar or non-polar?

31. Chlorofluorocarbons (CFCs) • Developed in the 1930's • Very stable compounds composed of C, F, Cl, & H • Freon is the tradename: • Trichlorofluoromethane • Dichlorodifluoromethane Trichloro-trifluoroethane Dichloro-tetrfluoroethane Chloropentafluoroethane

32. Safe,non-toxic, non-flammable alternative to dangerous substances (e.g. ammonia) for aerosol-spray propellants, refrigerants, solvents, and foam-blowing agents

33. CFCs and refrigeration CFCs and propellants

34. UV radiation in the stratosphere

35. The Ozone Layer Chemistry CFCl3 +UV Light==> CFCl2 +Cl Cl+ O3 ==> ClO + O2 ClO + O ==>Cl+ O2 The chlorine free radical atom is then able to attack another ozone molecule Cl+ O3 ==> ClO + O2 ClO + O ==>Cl+ O2 and again ... Cl+ O3 ==> ClO + O2 ClO + O ==>Cl+ O2 and again... thousands of times! A catalyst!

36. The ozone destruction process requires conditions cold enough (-80oC) for stratospheric clouds to form. Once these stratospheric clouds form the process can take place, even in warmer conditions

37. Ozone consumption has been greatly reduced, however CFCs may linger for another 150 years in the atmosphere 1997 ozone hole 2003 ozone hole Ozone layer thickness

38. Alcohol - R-OH C-C-OH (ethanol) (ethyl alcohol) Thiol - R-SH C-C-SH (ethanethiol) (ethyl mercaptan) Thiols = Mercaptans: sulfhydryl group (-SH) bonded to a saturated C atom

39. Physical Low BP No H-bonding Strong odor Skunks (3-methyl-1-butanethiol) Methanethiol (additive to natural gas) Morning breath Onions (1-propanethiol) Chemical Oxidation-Reduction 2 thiols <==> Disulfide Important in Protein chemistry Properties of Thiols

40. C-S-C C-S-C-C-C Ar-S-C C=C-S-C C=C-C-S-C C=C-C-S-S-C-C=C Morning Breath = Hydrogen sulfide Methanethiol Dimethyl sulfide… • Onions • Garlic Disulfides are important in some protein structures. Thioethers - replace the “O” with “S” (R-S-R)

41. What do you need to know? • Structural characteristics (know the functional group) • Alcohol • Phenol • Ether • Sulfur Analogs • Isomers • Nomenclature (the rules for naming the molecules) • Common & IUPAC • Physical properties (basic/simple) • BP; Solubility; Flammability • Occurrence and uses (common) • Natural (ex.: menthol, skunk, nutmeg, clove, garlic, onion) • Synthetic (ex.: antiseptics, racing fuel, de-icers, antioxidants, anesthetics) • Preparation (what basic reactions produce the molecules) • Alcohols - alkene hydration; Phenols - benzene hydration • Ethers - intermolecular alcohol dehydration • Characteristic reactions of the molecules • Combustion; dehydration; halogenation; oxidation