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Alcohols and Phenols.pptx

  1. Alcohols and Phenols Autor: University….
  2. Alcohols  Alcohols are compounds that posses a hydroxyl group (-OH), the name for this kind of group is characterized by ending in “ol”.  For example:  In the nomenclature of alcohols remember:  The name of the parent replace the suffix “e” by “ol”, example: pentane to pentanol  When choosing the parent, choose the longest chain that includes the carbon with the –OH.  Start the numertion of the parent starting from the end closest to the –OH group  The positions of the hydroxyl group must be indicated, example: 3-pentanol Source: Klein, David. Organic Chemistry. 3rd Edition.
  3. Classification of Alcohols  Alcohols can be designed as primary, secondary or tertiary, depending on the number of alkyl groups attached directly to the alpha position (this is the carbon atom bearing the –OH group) Source: Klein, David. Organic Chemistry. 3rd Edition.
  4. Physical properties of Alcohols  Alcohols have higher boiling points than alkanes due to the presence of the hydrogen bonding interactions that can be formed between the molecules of alcohols.  This property makes the interaction of alcohols with water fairly strong.  In this way alcohols have two regions. The hydrophobic region do not interact well with water (this is the hydrocarbon chain), and the hydrophilic region that does interact with water through hydrogen bonding (this is the –OH group). As the hydrophobic region increase the solubility of the alcohols decrease. Image from: /University%20Archives/1505050/Orga nic/Alcohols/Chapter%206/sec6-2/6- 2.htm Source: Klein, David. Organic Chemistry. 3rd Edition.
  5. Alcohol reactions  Reaction with active metals: Highly reactive metals like sodium (Na) react with alcohols to produce the corresponding alkoxide and hydrogen gas.  Example: 2CH3OH + 2Na → 2CH3ONa + H2  Substitution: alcohols react with acids to form halogenated hydrocarbons.  Example: CH3CH2OH + HBr → CH3CH2Br + H2O  Elimination or dehydration: in presence of concentrated acids such as H2SO4, alcohols react and eliminate water to form alkenes.  Example: CH3CH2OH + H2SO4 → CH2 = CH2 + H2O
  6. Alcohol reactions  Oxidation: this process involves the loose of a H bond and the formation of a C=O bond.  Common oxidizing reagent is chromic acid, H2CrO4.  The oxidation process will depend on the starting alcohol. Primary alcohols can by oxidized to aldehydes and this ones can be oxidizes to carboxylic acid. Secondary alcohols can be oxidized to ketones. Tertiary alcohols cannot be oxidized. Source: Klein, David. Organic Chemistry. 3rd Edition.
  7. Phenols  Phenols are compounds with an –OH group connected directly to a phenyl ring.  Phenol is more acidic than alcohols since the conjugate base is stabilized by resonance. Source: Klein, David. Organic Chemistry. 3rd Edition.

Hinweis der Redaktion

  1. Ketones cannot be oxidized because there is no more hydrogen atoms to get rid off. The same happens with the tertiary alcohols, the carbon atom have no H atoms bonded to it.