R-ATCHE-22

The following are products of the oxidation of alcohols.

Carboxylic acids

• (functional group) e.g. $CH_{3}COOH$ Hydrogen bonding between molecules:
• Relatively high M.P/B.P. Soluble in water.
• There exists two oxygens on the carboxylic acid that can attract hydrogens (this results in a hydrogen bond, although the double bonded oxygen should be a little weaker

Aldehydes:

• Slightly polar, medium M.P./B.P.? Not particularly soluble
• Cannot hydrogen bond with itself (no H). BUT CAN form hydrogen bonds with water! i.e. H from water can bond to the double bonded O. This O is known as a receptor

Ketones:

• Similar properties to aldehydes, probably less since disp forces weaker since distribution of electrons in less efficient. This was an incorrect assumption. Apparently, due to some wacky electron distribution rubbish, ketones will have a lower boiling point for whatever reason. This is so stupid. See this wacky discussion

Alcohols:

• $R-OH$

• e.g. Ethanol

Warning Depending on whether an alcohol is primary, secondary or tertiary, it reacts differently!

• Primary alcohols: when the hydroxyl (that's what the $-OH$ is) is on the end, i.e. when the hydroxyl group is bonded to a carbon that is bonded to one(or no) other carbon.
• Secondary alcohols: when the hydroxyl group is bonded to a carbon that is bonded to two other carbons.
• Tertiary alcohols: when the hydroxyl group is bonded to a carbon that is bonded to three other carbons.

Properties

• Hydrogen bonding between molecules - relatively high M.P/B.P. Soluble in water. (separate by distillation(wacky))

Oxidation processes

These process all contain oxidation half-reactions. For these processes to occur, we need something to reduce.

• Primary alcohol $\to$ Aldehyde $\to$ Carboxylic Acid

  • From Primary alcohol $\to$ Aldehyde, it is a variant of incomplete oxidation, i.e. partial. Complete oxidation would combust the organic compound, producing $CO_{2}$ and $H_{2}O$ which is inorganic.
  • From Aldehyde $\to$ Carboxylic Acid, this is a complete oxidation process. This is the final oxidation state for the carboxylic acid. Any further oxidation would be combustion.

• Secondary alcohol $\to$ Ketone

  • Like the carboxylic acid, the ketone is the final possible state of oxidation.
  • Evidently, to produce a ketone the initial hydroxyl group has to be within the chain, i.e. not on the ends (this results in the first reaction pathway(Primary alcohol $\to$ Aldehyde $\to$ Carboxylic Acid)).
  • This reaction also produces $H^{+}$ (2 of them! And also 2 $\overline{e}$)

• Tertiary $\to$ ???

  • They don't oxidise.

Example organic redox

• Ethanol shaken with excess acidified permanganate. $RED: 4\times MnO_{4}^{-} + 8H^{+} + 5\overline{e} \to Mn^{2+} + 4H_{2}O$ $OX: 5\times H_{2}O + C_{2}H_{5}OH \to CH_{3}COOH + 4H^{+} + 4\overline{e}$ $\therefore 4MnO_{4}^{-} + 5H_{2}O + 5C_{2}H_{5}OH + 32H^{+} \to 5CH_{3}COOH + 20H^{+} + 4Mn^{2+} + 16H_{2}O$ $\therefore 4MnO_{4}^{-} + 5C_{2}H_{5}OH + 12H^{+} \to 5CH_{3}COOH + 4Mn^{2+} + 11H_{2}O \checkmark$

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