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Ch. 23 Functional Groups

Ch. 23 Functional Groups. 23.1 Introduction to F unctional Groups. Most organic chemistry involves substituents that contain oxygen, nitrogen, sulfur, and/or phosphorus Functional Groups chemically functional part of the molecule

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Ch. 23 Functional Groups

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  1. Ch. 23 Functional Groups

  2. 23.1 Introduction to Functional Groups • Most organic chemistry involves substituents that contain oxygen, nitrogen, sulfur, and/or phosphorus • Functional Groups • chemically functional part of the molecule • a specific arrangement of atoms in a compound that is capable of characteristic chemical reactions

  3. Halocarbons • Contains at least one fluorine (F), chlorine (Cl), bromine (Br), or iodine (I) atom • Naming based on IUPAC rules for the name of the parent hydrocarbon

  4. Substitution Reactions • One atom or group of atoms replaces another atom or group of atoms • Important method for introducing a new functional group to an organic molecule • Ex. In general for a halogen substitution (halogenation) reaction • Ex. Reaction of methane with chlorine

  5. Substitution Reactions Halocarbons can be used to prepare alcohols Fluorine is more difficult to displace (generally not used for this purpose)

  6. 23.2 Alcohols, Ethers, and Amines • Alcohols: organic compounds with an –OH group (hydroxyl group) • IUPAC naming: drop the –e ending from the parent hydrocarbon and add –ol • Specify which C the –OH group is on with a number before the name • If multiple –OH groups, add number prefix to the –ol ending (ex. Butanol, butanediol, butanetriol)

  7. Properties of Alcohols • Capable of hydrogen bonding (intermolecular) • Somewhat soluble in water • Up to 4C alcohols are completely soluble in water • Longer hydrocarbon chains are not soluble because they are mostly nonpolar

  8. Uses of Alcohols • 2-propanol • Antiseptic • Base for perfumes, creams, lotions, other cosmetics • 1,2,3-propanetriol • Absorbs water from surroundings, used as a moistening agent in cosmetics, food, and pharmaceuticals • 1,2-ethanediol • antifreeze • Ethanol • Industrial uses (methanol added to “denature”)

  9. Fermentation • Production of ethanol from sugars by yeast or bacteria • Used to produce ethanol for alcoholic beverages *depressant, fatal in large doses

  10. Addition Reactions • A substance is added at a double or triple bond • Important method for introducing a new functional group to an organic molecule • Convert alkenes to alkanes

  11. Hydration Reactions • Water is added to an alkene (H + OH) • Forms an alcohol • Occurs under heat (100⁰C)

  12. Halogenation Reactions • Adds 1 or 2 halogens to an alkene or alkyne • Ex. Bromine has an orange color, but most unsaturated compounds form colorless halogenated compounds, so bromine is used to test whether a substance is saturated or not

  13. Hydrogenation Reactions

  14. Ethers • General formula: ROR • Naming: identify the two R groups (hydrocarbons), put in alphabetical order, and add ether to the end

  15. Ethers • Diethyl ether was the first reliable general anesthetic • Highly flammable and often causes nausea • Diphenyl ether is used in soaps and perfumes (geranium smell) • Boiling points between those of alcohols and hydrocarbons • Less soluble in water than alcohols • fewer hydrogen bonds

  16. Amines • Contain nitrogen (N) bonded to a carbon group • Similar to ammonia (NH3) • General formulas: RNH2, R2NH, or R3N • IUPAC naming: drop –e ending of parent hydrocarbon and add –amine • Hydrogen bonding is weaker than that of alcohols (N is less electronegative than O)

  17. Amines • Used in some dyes such as methyl orange (also used as an indicator)

  18. 23.3 Carbonyl Compounds • Carbonyl group: general structure C=O • Aldehyde: carbon of the carbonyl group is bonded to at least one hydrogen • Ketone: carbon of the carbonyl group is attached to two other carbons

  19. Aldehydes • IUPAC naming: identify and name the longest carbon chain that includes the carbonyl group (C=O), replace the –e ending of the parent hydrocarbon with –al • Most commonly used: methanal (formaldehyde) • making synthetic resins • Preserving biological specimens • Aromatic aldehydes produce scents/flavors ex. almond, vanilla, cinnamon

  20. Ketones • IUPAC naming: identify and name the longest carbon chain that includes the carbonyl group, change –e ending to –one, designate the carbonyl carbon with the lowest possible number • Most commonly used: propanone (acetone) • Solvent for resins, plastics, varnishes • Nail-polish remover

  21. Properties of Aldehydes and Ketones • No hydrogen bonding between aldehyde or ketone molecules (but weak H-bonds with water) • Weak polar attractions between carbonyl groups • Soluble in non-polar solvents • Smaller compounds are soluble in water

  22. Carboxylic Acids • Carboxyl group: carbonyl group bonded to a hydroxyl group (-COOH) • Carboxylic acid: organic compound with a carboxyl group • General formula: RCOOH • Weak acid (see below) • IUPAC naming: replace –e of parent hydrocarbon with –oic acid • Parent hydrocarbon number includes the carbon of the carboxyl group

  23. Carboxylic Acids • Abundant in nature • Citric acid = 2-hydroxypropane-1,2,3-tricarboxylic acid • Vinegar = acetic acid (acetum is Latin for vinegar) • Fatty acids: first isolated from fats

  24. Esters • Contain a carbonyl group and an ether link to the carbonyl carbon • General formula: RCOOR • Contribute characteristic odors to many fruits and perfumes • Neutral substances, cannot form H-bonds with other esters • Can be prepared from a carboxylic acid and an alcohol

  25. Esters heated in water do very little, but in presence of acid or base the ester breaks down rapidly

  26. 23.4 Polymers • Polymer: a large molecule of repeating smaller molecules covalently bonded together • Monomer: smaller molecules that join to form a polymer

  27. Addition Polymers • Form when unsaturated monomers react to form a polymer • Require monomers with double bonds • Often requires a catalyst to get the reaction started • Length of carbon chains can change properties

  28. Addition Polymer Examples • Polypropylene: stiffer plastic used for utensils and drink containers • Polystyrene: good insulator

  29. Addition Polymer Examples • Polyvinyl chloride (PVC): pipes to upholstery covering • Polytetrafluoroethene (PTFE): heat and corrosion resistant, nonstick, aka Teflon • Polyisoprene: rubber

  30. Condensation Polymers • Formed by the joining of monomers with the loss of a small molecule such as water • Polyesters: monomers of dicarboxylic acids and dihydroxy alcohols joined by ester bonds • Must have two functional groups on each monomer

  31. Condensation Polymer Examples • Polyamides: carboxylic acid and an amine • Kevlar: bullet-proof vests

  32. Condensation Polymer Examples • Nylon: fishing line, hosiery, zippers

  33. Condensation Polymer Examples • Nomex: flame-resistant clothing and electrical fixtures • Proteins

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