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Chemistry 102 Week 2 lecture

Chemistry 102 Week 2 lecture. Starting chapter 14 Organic and Biochemistry for the Allied Health Fields Dr Mark Deming. Organic Chemistry Part II. Compounds with O and N and sometimes S and P. Next few chapters compounds with OXYGEN.

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Chemistry 102 Week 2 lecture

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  1. Chemistry 102Week 2 lecture • Starting chapter 14 • Organic and Biochemistry for the Allied Health Fields • Dr Mark Deming

  2. Organic Chemistry Part II • Compounds with O and N and sometimes S and P

  3. Next few chapterscompounds with OXYGEN Alcohols Ethers Aldehydes Ketones Carboxylic acids Esters 1 CH 14 2 Connections to O CH 17 More oxidized 3 CH 18 CH 19 4

  4. Chapter 14(oxygen single bonded only) • Alcohols COH • Phenols ArOH (Ar=aromatic or benzene ring) • Ethers COC • Thiols CSH (and CSSC)

  5. Alcohol: has OH attached to aliphatic carbon • Hydroxy group --OH functional group • Phenol -OH attached to benzene • Ether - has an oxygen between carbons

  6. Naming of AlcoholsIUPAC 1. Name the longest chain to which a hydroxy group ( -OH) is attached and end in -ol 2. Number the longest chain to give the lowest number to the carbon with the hydroxy 3. Put location of hydroxy in front of root name 4. Locate and name any side groups in prefix

  7. Nomenclature

  8. Naming Alcohols Step 1: Name the longest chain to which the –OH group is attached. Use the alkane name of the chain, drop the –e ending, and replace it with –ol. Step 2: Number the longest chain to give the lowest number to the carbon with the –OH. Step 3: Locate the –OH position. Example: OH | CH3—CH2—CH2—CH—CH2—CH3 6 5 4 3 2 1 3-hexanol

  9. CH3 | OH | CH3 | Naming Alcohols, cont. Step 4: Locate and name any other groups attached to the longest chain. Step 5: Combine the name and location of other groups, the location of the –OH, and the longest chain into the final name. Example: CH3—CH2—CH2—CH—CH—CH3 6 5 4 3 2 1 2,4-dimethyl-3-hexanol

  10. Nomenclature • Problem: write the IUPAC name for each alcohol.

  11. Nomenclature • Solution:

  12. .

  13. Common Names for Alcohols • The alkyl group name is followed by the word alcohol • CH3OH methyl alcohol (IUPAC: methanol) • CH3CH2OH ethyl alcohol • CH3CHCH3 isopropyl alcohol OH

  14. VITAMIN B2 - Riboflavin Stimulates health andgrowth of hair, nails, skin cells. Helps eyes bybringing oxygen tobody tissues. Can help eliminatedandruff. May aid in preventing hair loss. Alcohol, poly functional, highly conjugated 14 atoms (16 atoms)

  15. Riboflavin, Vitamin B2 Highly conjugated 14 atoms (16 atoms) 14+ carbons conjugated becomes colorful This compound is a pale yellow solid named after latin flavis (yellow)

  16. Riboflavin is a water-soluble vitamin that was named from the Latin word flavius (yellow) to denote the deep color of crystals formed from the pure vitamin and the deep yellow color it gives to urine. Biochemically, riboflavin is metabolized to form the flavin coenzymes: flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). The functional moiety in both coenzymes is riboflavin's isoalloxazine ring system, which serves as a two-electron acceptor in enzymatic biochemical reductions. Enzymes that use a flavin cofactor are termed "flavoproteins" and have been extensively studied. Clinically, riboflavin promotes normal growth, helps with the breakdown of fat, and assists in the synthesis of steroids, red blood cells, and glycogen. Symptoms associated with riboflavin deficiency are inflammation of the tongue, light sensitivity, itching, dizziness, insomnia, and slow learning. In one open clinical study, high-dose riboflavin showed significant effectiveness as a migraine treatment. Common sources of riboflavin are almonds, yeast, cheese, eggs, chicken, beef, kidney, liver, and wheat germ.  • Recommended Dietary Allowances: Men = 1.7 mg; Women = 1.3 mg; Pregnant

  17. Alcohols are broken into two main groups: Aliphatic and Aromatic

  18. Aliphatic Alcohols • They come in three types: primary, secondary, tertiary • This is based on how they react in reactions but does not affect naming • Primary (1°): only 1 carbon attached to carbon with OH • KEY: end of a chain, has 2 H’s on carbon attached • Secondary (2°): two carbons attached to carbon with OH • KEY: middle of chain, has 1 H on carbon attached • Tertiary (3°): three carbons attached to carbon with OH • KEY: middle of chain and NO H’s on carbon attached but it has an extra carbon attached to it.

  19. Can You find all the types of OH’s? (primary, secondary, tertiary, aromatic) 1-aromatic 2-primary 3-aromatic 4-tertiary 5-secondary 6-primary 7-secondary 8-secondary 9-primary 10-aromatic 11-primary 12-tertiary 13-tertiary 14-secondary Caution: these molecules were made up and may not be biologically relevant

  20. Polar and Hydrogen Bonding • We will focus today on the concept of • Polarity • Hydrogen bonding

  21. Intermolecular Forces (between molecules) Ionicmust be an ionic compound (made of full charges)starts with metal or ammonium (acid-base salts) Super H-bondingH-bonding + polar + partially ionizescarboxylic acid COOH H-bonding from a O-H > N-H to a lone pair on O: > N:Amide (with H) > alcohol (OH) > amine (NH) Dipolar net polar moleculeester > amide (no H) > aldehyde > ketone > ether London Dispersion Forces (LDF)Non polar molecule (all molecules) aromatic > -ynes > -enes > -anes (only C,H) Same force higher mass  higher mp, higher bp, lower vapor pressure Same approx. mass higher force  higher mp, higher bp, lower vapor pressure = Energy of Attraction (additive) Energy of Disruption High TEMP(higher velocity) gas bp Acid -CO2H Low Mass (MW) High Vibration High Velocity Starts with at given temp.(same force)High Mass (MW) Low Vibration Low Velocity Has OH or NH liquid Increase Energy of Attraction Increase Energy of Disruption mp Has O or N solid Low TEMP(lower velocity)

  22. Polarity • Polarity happens when an atom has an unequal pull on electrons • H C N O P S Cl • 2.1 2.4 3.0 3.5 2.1 2.4 3.0 • The bigger the number below (electronegativity, EN) the more pull and if difference in EN is 0.4 or less then nonpolar

  23. Polarity cont. • Example C O charge separation δ+ δ

  24. Physical Properties • Alcohols are polar molecules • The C-O and O-H bonds are both polar covalent.

  25. IMF (Intermolecular Forces)alcohols and ether All molecules have LDF Polar if has O or N H-bonding if O-H or N-H to O or N Alcohols have LDF and are polar and can both give and receive an H-bond Ethers are polar but can only receive an H-bond ·· ·· give receive

  26. Hydrogen Bond • A special connection between molecules • One molecule must give an H-bond and one molecule must take an H-bond • To give an H-bond the molecule must have an O-H or an N-H bond (NOT C-H) • To take an H-bond the molecule must have and O or N with three or less connections (at least one lone pair)

  27. Alcohol to Water bonding Receive H-bond Receive H-bond Give H-bond Give H-bond

  28. Polar + H-bondingHydrophilic Alkane likeNon PolarHydrophobic Important: Expected to knowRule of thumb: Each OH can make soluble 3 carbons

  29. more soluble Solubility of alcohols in water Soluble-one layer insoluble-two layers less soluble Four carbons is at the edge of visual solubility not soluble Remember that solubility means dissolve in (or mix with) another chemical Fig. 13-2, p.419

  30. Physical Properties of pure alcohols • In the liquid state, alcohols associate to each other by hydrogen bonding.

  31. Alcohol to alcohol bonding

  32. Note: C3 and C2O are about the same weight, both have 3 big atoms near each other in the table. Difference must be type of IMF. C4O C2O C5 C3

  33. Physical Properties • bp increases as MW increases. • Solubility in water decreases as MW increases.

  34. Acidity of Alcohols • Alcohols have about the same pKa values as water; aqueous solutions of alcohols have the same pH as that of pure water. • Alcohols and phenols both contain an OH group. • Phenols are weak acids and react with NaOH and other strong bases to form water-soluble salts. • Alcohols are not acids and do not react in this manner.

  35. REACTIONS of Alcohols In this chapter you are responsible for: • Elimination Reactions • To form alkenes (a type of reduction) • To form ethers (neutral ) • Oxidation Reactions • Of primary and secondary alcohols • Tertiary and aromatic unreactive to oxidation Note: other alcohol reactions we will see in future chaptersChapter 16- aldehydes and ketones react with alcohols to form acetals and ketalsChapter 17- carboxylic acids react with alcohols to become esters

  36. Reactions of Alcohols CO2 + H2O EthersNOT REACTIVE Alcohol excess O2  Combustion  C + H2O or CO + H2O limited O2 Dehydration([H], Reduction) ( losing H20 ) [O] Oxidation [O]=oxidizing agent 180ºC 140ºC end middle Alkene Ether If primary (1º) If secondary (2º) If tertiary (3º) Aldehyde Ketone No Reaction Carboxylic Acid [O]

  37. Reactions of Alcohols Dehydration of alcohols to give ethers Dehydration of alcohols to give alkenes [H]- Reduction High concentration Low concentration Oxidation of Primary (1º) alcohol Oxidation of secondary (2º) alcohol Oxidation of Tertiary (3º) alcohol NO REACTION – NADA – NOTHING – NO WAY

  38. Alcohol Reactions- Elimination Elimination Reaction -remove a molecule • Dehydration to form a double bond: Elimination of H2O to form double bond • Dehydration to form an ether Elimination of H2O to from 2 alcohols form an ether

  39. Elimination Reactions of Alcohol (cont) Elimination Reaction of an Alcohol to form alkenes The removal of water (dehydration) from an alcohol is an elimination reaction and produces an alkene. Strong Acid Catalyst The alcohol is usually in low concentrations to avoid ether formation

  40. Elimination Reactions of Alcohol (cont) Dehydration to form Ethers. Under slightly different conditions, a dehydration reaction can occur between two alcohol molecules to produce an ether. The alcohol is usually in high concentration and lower temperature to avoid alkene formation

  41. Reactions of Alcohols- Oxidation • Official Definitions: (chem 102 does not use) • Oxidation is really the losing of electrons at an atom by formal electron counting • Reduction is the gaining of the electrons at an atom • Practical Usage in this class: At a CARBON [H] [O]

  42. Reactions of Alcohols- Oxidation Remember that Oxidation: Is the gain of oxygens or the loss of hydrogens at a carbon. Usually done with a chemical that will itself get reduced called an oxidizing agent: and we will abbreviate it with [O]

  43. Reactions of Alcohols- Oxidation • Oxidation of Aliphatic Alcohols • Primary alcohols  aldehyde  carboxylic acid. • Secondary alcohols  ketone. • Tertiary alcohols  no reaction. • Oxidation of Aromatic Alcohols • No reaction- not easily oxidized

  44. Note: most strong oxidizing agents will make the reaction go all the way to the carboxylic acid Alcohol Reactions, cont. Primary alcohol oxidation Secondary alcohol oxidation

  45. Potassium ChromateK2Cr2O4 (The oxidizing agent) Ethanol These are the reactants Fig. 13-7a, p.423

  46. Ethanol is oxidized to acetic acid Chromate is reduced (green-grey) When mixed the products are in the second tube Fig. 13-7b, p.423

  47. Important Alcohols • Methanol • Ethanol • Isopropyl alcohol • Glycerol • Aromatic alcohols • Phenol, BHA, BHT

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