alcohol

Examples of alcohol in the following topics:

• Absorption of Alcohol

  • Alcohol is metabolized (by alcohol dehydrogenase enzymes made in the liver) when it is absorbed into the bloodstream.
  • Alcohol absorption can be slowed by ingesting alcohol on a full stomach.
  • Alcohol in non-carbonated beverages is absorbed more slowly than alcohol in carbonated drinks.
  • Chronic alcohol abuse can cause fatty liver, cirrhosis and alcoholic hepatitis .
  • Chronic alcohol abuse can cause fatty liver, cirrhosis and alcoholic hepatitis.

• Reactions of Alcohols

  • Alcohols can undergo elimination, but only by E1.
  • The acid protonates the alcohol to make it a good leaving group, then the halide displaces the alcohol with nucleophilic attack on the electrophilic carbon.
  • Although tertiary alcohols cannot be oxidized, secondary alcohols can be converted to ketones using an oxidizing agent.
  • On the left, a tertiary alcohol undergoes an SN1 reaction.
  • On the right, a primary alcohol undergoes an SN2 reaction.

• Alcohols

  • Alcohols are functional groups characterized by the presence of an -OH group.
  • Alcohols are an important class of molecules with many scientific, medical, and industrial uses.
  • The structure of an alcohol is similar to that of water, as it has a bent shape.
  • Alcohols are able to participate in many chemical reactions.
  • Alcohols have many uses in our everyday world.

• Alcohol Reactions

  • The functional group of the alcohols is the hydroxyl group, –OH.
  • Indeed, the dipolar nature of the O–H bond is such that alcohols are much stronger acids than alkanes (by roughly 1030 times), and nearly that much stronger than ethers (oxygen substituted alkanes that do not have an O–H group).
  • The most reactive site in an alcohol molecule is the hydroxyl group, despite the fact that the O–H bond strength is significantly greater than that of the C–C, C–H and C–O bonds, demonstrating again the difference between thermodynamic and chemical stability.

• Oxidation of Alcohols by DMSO

  • One source of oxygen that has proven effective for the oxidation of alcohols is the simple sulfoxide solvent, DMSO.
  • The reaction is operationally easy: a DMSO solution of the alcohol is treated with one of several electrophilic dehydrating reagents (E).
  • The alcohol is oxidized; DMSO is reduced to dimethyl sulfide; and water is taken up by the electrophile.
  • Bonding of sulfur to the alcohol oxygen atom then follows.
  • The remaining steps are eliminations, similar in nature to those proposed for other alcohol oxidations.

• Nucleophilic Substitution of the Hydroxyl Group

  • As was true for alkyl halides, nucleophilic substitution of 1º-alcohols proceeds by an SN2 mechanism, whereas 3º-alcohols react by an SN1 mechanism.
  • Alcohols having acid sensitive groups would, of course, not tolerate such treatment.
  • Phosphorous tribromide is best used with 1º-alcohols, since 2º-alcohols often give rearrangement by-products resulting from competing SN1 reactions.
  • The last example shows the reaction of thionyl chloride with a chiral 2º-alcohol.
  • This aspect of alcohol chemistry will be touched upon in the next section.

• Wine, Beer, and Alcohol

  • Humans have been producing alcoholic beverages for thousands of years.
  • The production of alcohol in these drinks is based primarily on yeast fermentation.
  • When making red wine, there is an additional fermentation step after alcoholic fermentation.
  • Beer is the most consumed alcoholic beverage in the world.
  • A few examples are sake (uses the fungus Aspergillus oryzae to facilitate starch fermentation from rice), brandy, whiskey (both are distilled alcohol), and other alcohol beverages with higher percentage of alcohol compared to wine and beer.

• Elimination Reactions of Alcohols

  • Most alcohols are slightly weaker acids than water so the left side is favored.
  • The elimination of water from an alcohol is called dehydration.
  • This procedure is also effective with hindered 2º-alcohols, but for unhindered and 1º-alcohols an SN2 chloride ion substitution of the chlorophosphate intermediate competes with elimination.
  • The first equation shows the dehydration of a 3º-alcohol.
  • The second example shows two elimination procedures applied to the same 2º-alcohol.

• Alcohol Nomenclature

  • Alcohols are usually named by the first procedure and are designated by an ol suffix, as in ethanol, CH3CH2OH (note that a locator number is not needed on a two-carbon chain).
  • For the mono-functional alcohols, this common system consists of naming the alkyl group followed by the word alcohol.
  • Alcohols may also be classified as primary, 1º, secondary, 2º & tertiary, 3º, in the same manner as alkyl halides.
  • The chemistry of thiols will not be described here, other than to note that they are stronger acids and more powerful nucleophiles than alcohols.

• Prohibition

  • Prohibition was a national ban on the sale, manufacture and transportation of alcohol that lasted from 1920–1933.
  • To prevent bootleggers from using industrial ethyl alcohol to produce illegal beverages, the government ordered the poisoning of industrial alcohols.
  • In response, the Treasury Department required manufacturers to add even more deadly poisons to industrial alcohols, including Sterno (or "canned heat") and the particularly deadly methyl alcohol.
  • As many as 10,000 people died from drinking denatured alcohol before Prohibition ended.
  • The 18th Amendment had outlawed "intoxicating liquors for beverage purposes" but did not set a limit on alcohol content, which the Volstead Act did by establishing a limit of .5% alcohol per unit.