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    26sec3 26sec3 Presentation Transcript

    • 26.3 Carbonyl Compounds
    • Aldehydes and Ketones
      • Review :
        • alcohol has an oxygen bonded to a carbon group and a hydrogen
        • ether has an oxygen bonded to two carbon groups
      • An oxygen can also be bonded to a single carbon by a double bond
    • Aldehydes and Ketones
      • The C=O group is called the “carbonyl group”
        • it is the functional group in both aldehydes and ketones
      • Aldehydes - carbonyl group always joined to at least one hydrogen (meaning it is always on the end !)
    • Aldehydes and Ketones
      • Ketones - the carbon of the carbonyl group is joined to two other carbons (meaning it is never on the end)
      • Structures - middle of page 785
    • Aldehydes and Ketones
      • Naming?
        • Aldehydes: identify longest chain containing the carbonyl group, then the -e ending replaced by -al , such as methan al , ethan al , etc.
        • Ketones: longest chain w/carbonyl, then new ending of -one ; number it?
      • propan one , 2-pentan one , 3-pentan one
    • Aldehydes and Ketones
      • Table 26.4, page 786 examples
      • Neither can form intermolecular hydrogen bonds, thus a much lower b.p. than corresponding alcohols
      • wide variety have been isolated from plants and animals; possible fragrant odor or taste; many common names
    • Aldehydes and Ketones
      • Benzaldehyde
      • Cinnamaldehyde
      • Vanillin
      • Methanal (the common name is: formaldehyde)
        • 40% in water is formalin, a preservative
    • Aldehydes and Ketones
      • Propanone (common: acetone) is a good solvent; miscible with water in all proportions
      • why is it a good substance used in nail-polish removers? (a powerful solvent-able to dissolve both polar & nonpolar)
    • The Carboxylic Acids…
      • Also have a carbonyl group (C=O), but is also attached to a hydroxyl group (-OH) = “carboxyl” group
      • general formula: R-COOH
        • weak acids (ionize slightly)
      • Named by replacing -e with -oic and followed by the word acid
      • methan oic acid; ethan oic acid
    • Carboxylic Acids
      • Abundant and widely distributed in nature, many having a Greek or Latin word describing their origin
        • acetic acid (ethanoic acid) from acetum, meaning vinegar
        • many that were isolated from fats are called fatty acids
      • Table 26.6 page 789
    • The Esters…
      • General formula: RCOOR
      • Derivatives of the carboxylic acids, in which the -OH from the carboxyl group is replaced by an -OR from an alcohol:
        • carboxylic acid + alcohol  ester + water
      • many esters have pleasant, fruity odors- banana, pineapple, perfumes
    • Esters
      • Although polar, they do not form hydrogen bonds (reason: there is no hydrogen bonded to a highly electronegative atom!)
        • thus, much lower b.p. than the hydrogen-bonded carboxylic acids they came from
    • Esters
      • Can be prepared from a carboxylic acid and an alcohol; usually a trace of mineral acid added as catalyst (because acids are dehydrating agents)
      • Note equation on bottom p. 790
    • Esters
      • Naming? It has 2 words:
        • 1st: alkyl attached to single bonded oxygen from alcohol
        • 2nd: take the acid name, remove the -ic acid , add -ate
      • example on top of page 743
    • Oxidation- Reduction Reactions
      • All of the previous clases of organic compounds are related by oxidation and reduction reactions
      • What is oxidation-reduction?
        • Oxidation: the gain of oxygen, loss of hydrogen, or loss of e -1
        • Reduction: the loss of oxygen, gain of hydrogen, or gain of e -1
    • Oxidation- Reduction Reactions
      • Oxidation and reduction reactions (sometimes called redox) are coupled- one does not occur without the other
      • The number of Oxygen and Hydrogen attached to Carbon indicates the degree of oxidation
    • Oxidation- Reduction Reactions
      • The fewer the # of H on a C-C bond, the more oxidized the bond
        • Thus, a triple bond is more oxidized than a double bond and a single bond
      • An alkane is oxidized (loss of H) to an alkene, and then to an alkyne
    • Oxidation- Reduction Reactions
      • Loss of hydrogen is called a dehydrogenation reaction
        • may require strong heating and a catalyst
      • Note equations at the top on page 791
    • Oxidation- Reduction Reactions
      • Methane can be oxidized in steps to carbon dioxide (top p. 792):
        • methane  methanol  methanal  methanoic acid  CO 2
      • the more reduced (more H) a carbon compound, the more energy it can release upon oxidation
    • Oxidation- Reduction Reactions
      • Alcohols can also be oxidized into other products
      • “ Dr. Al K. Hall  Mr. Al D. Hyde”
      • Equations middle of page 792
      • Preparing aldehydes from a primary alcohol is a problem, because they are then easily oxidized to carboxylic acids
    • Oxidation- Reduction Reactions
      • Benedict’s test and Fehling’s test are commonly used for aldehyde detection – Figure 26.18 p. 793