Oxygen Containing Organic Molecules

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Oxygen Containing Organic Molecules
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Alcohol and Ether-Single Bonded Oxygens

• Alcohols
• 1. Contain functional group OH, hydroxyl
• 2. Naming comes from alkane name of main chain
• a. count carbons to make chain
• b. add suffix ol instead of ane
• example ethanol instead of ethane.
• c. Number the carbon on which the OH is
• found
• 3. Alcohols are either primary, secondary or
  tertiary, based on where the OH group is
  attached
• a. Primary if on a C attached to only one other
  carbon
• b. Secondary if on a C attached to two other
  carbons
• c. Tertiary if on a C attached to three other
  carbons

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Examples
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Alcohols

•  OH group is polar and makes the alcohol more
  likely to dissolve in polar solvents such as
  water. This effect is less in long chain
  alcohols with only one OH. The effect is due to
  hydrogen bonding.
• Alcohols have much higher boiling points than the
  alkane they come from, also due to hydrogen
  bonding.

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Alcohols

• Important straight chain alcohols
• a. Methanol-made by heating wood in absence of
  air, often called wood alcohol, very
  poisonous-2tbsp can cause death.
• b. Ethanol- fermentation product of glucose by
  yeast. Common alcohol in alcoholic beverages.
• c. Polyhydric alcohols- more than one OH
• 1. Ethylene glycol-used in car antifreeze
• 2. Glycerol-used in hand lotion and
  cosmetics-also called glycerin

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Alcohols

• Cyclic and Aromatic alcohols
• a. Hydroxyl groups can be found on many
  hydrocarbons-Oil of peppermint-menthol is a
  substituted cyclohexane.
• b. Aromatic alcohols
• i. Phenol- very corrosive to skin, once used
  as an antiseptic
• ii. Substituted phenols now used as
  antiseptics e. g. hexachlorophene
• iii. Some are very irritating-urushiol, oil of
  poison ivy

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Preparation of Alcohols

• By hydration of alkenes-
• Reactions of alcohols
• a. Dehydration- opposite of hydration
• b. Oxidation by KMnO4, K2Cr2O7, or CrO3
• i. Primary alcohols become aldehydes
• ii. Secondary alcohols become ketones
• iii. Tertiary alcohols cannot be oxidized

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Ethers

• Structure-carbon groups connected through an
  oxygen
• Naming-simply name the side groups on either side
  of the oxygen.
• Ethers can be used as anesthetics like
  cyclopropane. They are safer to use though
  slower in action
• Preparation-by dehydration of alcohols at lower
  temperature

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Homework 13-a

• p. 319 CYU all
• p. 324 CYU all
• p. 329 CYU all
• p. 347ff 3, 4, 5, 6, 7, 8, 14, 16

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Aldehydes and Ketones

• Both aldehydes and ketones contain the carbonyl-
  functional group
• The carbonyl is in many organic and biochemicals
  such as lipids, carbohydrates, proteins, and
  nucleic acids
• Aldehydes have the carbonyl at the end of a
  carbon chain
• Ketones have the carbonyl within the carbon chain

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Aldehydes and Ketones

• Naming is similar to alkanes and alkenes in
  counting the longest carbon chain.
• Since in aldehydes the carbonyl is at the end of
  a chain, it is always carbon 1 the ending is
  changed to al instead of ane or ene
• Ketones must have their carbonyl group numbered,
  as it can be anywhere in the chain except the ends

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Examples
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Important Aldehydes and Ketones

• H
• Formaldehyde H-CO
• used as a preservative for biological samples
• Acetone H3C-C-CH3 used as a water soluble
• O organic solvent, as in nail
• polish remover
• Many flavorings and perfumes are aldehydes or
  ketones, such as cinnamon--cinnamaldehyde

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Synthesis of Aldehydes and Ketones

• From primary alcohols, oxidation removes two Hs
  and creates aldehydes
• From secondary alcohols, oxidation removes 2 Hs
  and creates ketones
• Tertiary alcohols cannot be oxidized in this
  fashion

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Reactions of Aldehydes and Ketones

• Reduction (hydrogenation)the opposite of
  oxidation, reforms the respective alcohol
• Oxidation of aldehydes creates carboxylic acids
• Ketones do not oxidize in this fashion

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Reactions of Aldehydes and Ketones

• A special reaction is the formation of
  hemi-acetals and ketals, when and aldehyde or
  ketone react with an alcohol
• This can happen even on the same molecule if both
  functional groups are present
• A similar reaction happens to make the hemiketal
  fructose

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Homework 13-b

• p. 336 CYU all
• p 349ff 20, 21, 26

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Carboxylic Acids

• Oxidation of aldehydes created the carboxylic
  acids, noted before, containing the carboxyl-
  group
• Carboxylic acids can create hydrogen bonds, so
  they will have much higher melting and boiling
  points and water solubility than most organic
  compounds.

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Carboxylic Acids

• Naming rules
• Since the carboxyl group is at the end of the
  chain, it is the 1 carbon. The ending put on
  these is oic acid If double bonds are within the
  chain, the suffix ene goes before the acid
  suffix (butanoic vs. 2-butenoic)

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Carboxylic Acids

• Important carboxylic acids
• Formic (methanoic) acidformed from methanol by
  the liver, very toxic to the body
• Acetic (ethanoic) acidthe reason for the sour
  taste and strong smell of vinegar
• Oxalic acidvery toxic acid found in the leaves
  of many plants
• Benzoic acidused as a preservative and
  protectant from UV rays

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Synthesis and Reactions of Carboxylic Acids

• Synthesis by oxidation of primary alcohols or
  aldehydes
• Ionizationseparation into H and an anion in
  water solution
• Esterificationan important combination of an
  alcohol and an acid

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Homework 13c

• p. 338 CYU all
• p. 349ff 24, 28, 29, 32, 34

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Esters

• The ester functional group is an adaptation of
  the carboxyl group and is found in the middle of
  two chains of carbons.
• Naming esters is done by changing the name of the
  alcohol portion by switching endings-ol to yl
  then change the ending of the acid portion to -ate

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Esters

• Important esters include many pleasant tastes and
  smell, but also some important drugs.
• Nitroglycerin is an ester of 1,2,3-propanetriol
  and nitric acid. It is not only an explosive, but
  also lowers blood pressure for those with heart
  problems
• Methyl salicylate is the flavoring oil of
  wintergreen. It is used in muscle pain ointments
• Aspirin is also called acetyl salicylic acid, and
  is an ester used extensively as a pain medication

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Reactions of Esters

• Hydrolysis breaks the ester linkage to reform
  both acid and alcohol
• Saponification breaks the linkage with NaOH and
  forms the sodium salt of the acid, which acts as
  a soap

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Homework 13d

• p. 342 CYU all
• p. 351ff 36, 37, 38, 39, 42, 43