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  1. 1. 26.2 Alcohols and Ethers
  2. 2. Alcohols <ul><li>Alcohols - a class of organic compounds with an -OH group </li></ul><ul><ul><li>The -OH functional group in alcohols is called a “hydroxyl” group; thus R-OH is the formula </li></ul></ul><ul><li>How is this different from the hydroxide ion? (covalent bonding with the carbon- not ionic with a metal like bases) </li></ul>
  3. 3. Alcohols <ul><li>Aliphatic alcohols classified into categories according to the number of R groups attached to the carbon with the hydroxyl </li></ul><ul><ul><li>1 R group: primary alcohol </li></ul></ul><ul><ul><li>2 R groups: sec ondary alcohol </li></ul></ul><ul><ul><li>3 R groups: tert iary alcohol </li></ul></ul><ul><li>Note drawings on page 778 </li></ul>
  4. 4. Alcohols <ul><li>Both IUPAC and common names </li></ul><ul><li>For IUPAC: </li></ul><ul><ul><li>drop the -e ending of the parent alkane name; add ending of -ol , number the position of -OH </li></ul></ul><ul><ul><li>parent is the longest chain that contains the carbon with the hydroxyl attached . </li></ul></ul>
  5. 5. Alcohols <ul><li>The hydroxyl is given the lowest position number </li></ul><ul><li>Alcohols containing 2, 3, and 4 of the -OH substituents are named diols, triols, and tetrols respectively </li></ul><ul><ul><li>Examples on page 779 </li></ul></ul>
  6. 6. Alcohols <ul><li>Common names: </li></ul><ul><ul><li>similar to halocarbons, meaning name the alkyl group, then followed by the word alcohol </li></ul></ul><ul><ul><li>One carbon alcohol = methyl alcohol </li></ul></ul>
  7. 7. Alcohols <ul><li>More than one -OH substituents are called glycols (ethylene glycol?) </li></ul><ul><li>** Examples on page 779 ** </li></ul><ul><li>Phenols - compounds in which a hydroxyl group is attached directly to an aromatic ring. Cresol is the common name of o , m , and p isomers of methylphenol </li></ul>
  8. 8. Properties of Alcohols <ul><li>Much like water, alcohols are capable of hydrogen bonding between molecules </li></ul><ul><ul><li>this means they will boil at a higher temp. than alkanes and halocarbons with a comparable number of atoms </li></ul></ul>
  9. 9. Properties of Alcohols <ul><li>Alcohols are derivates of water; the -OH comes from water, and thus are somewhat soluble </li></ul><ul><li>Alcohols of up to 4 carbons are soluble in water in all proportions; more than 4 carbons are usually less soluble, because the longer carbon chain is more nonpolar </li></ul>
  10. 10. Properties of Alcohols <ul><li>Many aliphatic alcohols used in laboratories, clinics, and industry </li></ul><ul><ul><li>Isopropyl alcohol (2-propanol) is rubbing alcohol; used as antiseptic, and a base for perfume, creams, lotions, and other cosmetics </li></ul></ul><ul><li>Ethylene glycol (1,2-ethanediol) - commonly sold as “antifreeze” </li></ul>
  11. 11. Properties of Alcohols <ul><li>Glycerol (1,2,3-propanetriol) - used as a moistening agent in cosmetics, foods, and drugs; also a component of fats and oils </li></ul><ul><li>Ethyl alcohol (ethanol) used in the intoxicating beverages; also an important industrial solvent </li></ul>
  12. 12. Properties of Alcohols <ul><li>Denatured alcohol - means it has been made poisonous by the addition of other chemicals, often methyl alcohol (methanol, or wood alcohol). </li></ul><ul><li>As little as 10 mL of methanol has been known to cause permanent blindness, and 30 ml has resulted in death! </li></ul>
  13. 13. Addition Reactions <ul><li>The carbon-carbon single bond is not easy to break </li></ul><ul><li>In double bonded alkenes, it is easier to break a bond </li></ul><ul><li>Addition reaction - substance is added at the double or triple bond location, after it is broken </li></ul>
  14. 14. Addition Reactions <ul><li>Addition of water to an alkene is a hydration reaction - usually occurs with heat and an acid (such as HCl or H 2 SO 4 acting as a catalyst) </li></ul><ul><li>Note sample at top of page 782 for the formation of ethanol from ethene + water </li></ul>
  15. 15. Addition Reactions <ul><li>If a halogen is added in an addition reaction, the result is a halocarbon that is disubstituted - middle p. 782 </li></ul><ul><li>The addition of bromine is often used as a test for saturation - p.782 </li></ul><ul><li>Addition of a hydrogen halide? -called monosubstituted halocarbon </li></ul>
  16. 16. Addition Reactions <ul><li>Addition of hydrogen to produce an alkane is a hydrogenation reaction , which usually involves a catalyst such as Pt or Pd </li></ul><ul><ul><li>common application is the manufacture of margarine from unsaturated vegetable oils (making them solid from a liquid) </li></ul></ul>
  17. 17. Addition Reactions <ul><li>The hydrogenation of a double bond is a reduction reaction , which in one sense is defined as the “gain of H” </li></ul><ul><li>Bottom of page 77,82 ethene is “reduced” to ethane; cyclohexene is “reduced” to cyclohexane </li></ul>
  18. 18. Ethers <ul><li>A class of organic compounds in which oxygen is bonded to 2 carbon groups: R-O-R is formula </li></ul><ul><li>Naming? The two R groups are alphabetized, and followed by ether </li></ul><ul><li>Two R groups the same? Use the prefix di- Examples on page 783 </li></ul>
  19. 19. Ethers <ul><li>Diethyl ether is the one commonly called just “ether” </li></ul><ul><ul><li>was the first reliable general anesthetic </li></ul></ul><ul><ul><li>dangerous- highly flammable, also causes nausea </li></ul></ul><ul><li>ethers are fairly soluble in water </li></ul><ul><li>Alcohol used for fuel in the future? </li></ul>
  20. 20. Ethers <ul><li>Ethers usually have lower boiling pts than alcohols, but higher than hydrocarbons and halocarbons of similar mass </li></ul><ul><li>Ethers are usually less soluble than alcohols, but more soluble than hydrocarbons and halocarbons </li></ul><ul><li>Reason for the above: ethers have no hydroxyl group for H-bonding like in alcohols, but do have an oxygen that accepts H </li></ul>