QUIMICA UNDECIMO SEMANA 15 FINAL

Main ideas and concepts (Aldehydes and how to make them)

• Aldehydes are organic compounds characterized by the carbonyl functional group (C=O):
  • The carbonyl carbon is double-bonded to oxygen.
  • The carbonyl carbon is also single-bonded to hydrogen (making the carbonyl group terminal in aldehydes).
• Aldehydes can undergo reactions that involve losing/shareing electrons, leading to outcomes such as:
  • Addition reactions
  • Oxidation reactions

Key reaction/learning vocabulary (Monte Rosales capsule)

Five functional group names are introduced (with English equivalents):

• Alcohols
• Nitriles (nitrile)
• Alkenes
• Alkynes
• Esters

Uses of aldehydes (why they matter)

The video explains that aldehyde reactions and derivatives support important industrial/chemical applications, including:

• Oxidation of aldehydes → carboxylic acids
  • Used in producing organic acids for food, pharmaceuticals, and chemical industries.
• Reduction of aldehydes → primary alcohols
  • Important for producing alcohols and specialized chemicals.
• Aldehyde + alcohol → acetals
  • Used as a functional group protection strategy to prevent unwanted reactions during synthesis.
• Aldehyde + hydrogen cyanide → cyanohydrins
  • Used to build more complex molecules (including pharmaceutical-related synthesis).
• Aldol condensation
  • Enables carbon–carbon bond formation, producing larger molecules.
  • Also used for resins and polymers.
• Formaldehyde and aromatic compound synthesis
  • Formaldehyde is used in making resins/polymers (e.g., plastics).
  • Aldehydes can help form aromatic compounds (industry uses include rubber and pharmaceuticals).

Five main “how to obtain aldehydes” reactions

The instructor focuses on major reactions that produce aldehydes, describing mechanisms/conditions and examples.

1) Oxidation of primary alcohols → aldehydes

• Starting point: a primary alcohol
• Key idea: oxidizing primary alcohols yields aldehydes
• Important emphasis: correct catalysts and reaction components matter.
• Example mentioned:
  • Catalyst: pyridinium chlorochromate
  • Other reagent/component: oxochloroisocyanurate
  • Product: ethanal (from ethanol)

2) Oxidation of alkenes → aldehydes + ketones

• Oxidant/method: potassium permanganate
• Conditions emphasized:
  • Concentrated
  • Hot acidic medium
• Outcome:
  • Break the alkene double bond so oxygen ends up on each side.
  • The video stresses that aldehydes formed will be terminal.
• How to distinguish aldehyde vs ketone (as taught):
  • Aldehyde: carbonyl carbon has H → terminal
  • Ketone-like structure: carbonyl carbon typically between two carbons (no aldehyde hydrogen)
• Example concept shown:
  • The mechanism breaks the double bond and forms one side as an aldehyde and the other as a ketone.

3) Freidel–Crafts acylation / aromatic formylation logic

• Purpose (as described):
  • Used mainly to obtain aromatic ketones (acylation part).
• For forming aldehydes (formyl group introduction):
  • The instructor describes a G–C reaction approach (Gattermann–Koch-type logic) for adding a formyl group / aldehyde formation.
• Constraints/limitations:
  • Works on benzene and activated benzene derivatives
  • Cannot use highly deactivated benzene derivatives because the needed position won’t be activated.
• Example conditions mentioned:
  • Hydrochloric acid + carbon monoxide
  • With benzene and an activating group (example given: halogen/activating group, described as a “G group”)
  • Produces a benzene derivative containing the aldehyde/formyl function.

4) Hydration of alkynes → enol → aldehyde or ketone

• Reactants/conditions:
  • Aqueous sulfuric acid
  • Mercury catalyst
• Sequence described:
  1. Alkyne hydration forms an enol
  2. The enol isomerizes rapidly under reaction conditions
  3. The product becomes an aldehyde or ketone (video focuses on the aldehyde case)
• Placement concept emphasized:
  • Mentions anti–carbon bonding (hydrogen and oxygen placement rule)
  • Oxygen goes to the carbon position corresponding to fewer hydrogens (as taught in the video).

5) Converting nitriles / acid chlorides / esters → aldehydes

The instructor groups several precursor transformations that end in aldehydes.

5a) Nitriles → aldehydes

• Starting point: nitrile = carbon chain attached to C≡N
• Process described (two-step transformation):
  1. Convert the triple bond C≡N into a double bond (example involving an aluminum complex)
  2. Add H₃O (hydronium) so nitrogen leaves (forming NH₄), and oxygen enters to form the aldehyde
• Example reference:
  • The “red large chain” attached to the nitrile carbon becomes part of the aldehyde framework.

5b) Acid chlorides → aldehydes

• Concept: reduction of acid chlorides yields aldehydes.
• Example elements mentioned:
  • Presence of lithium
  • Catalysts/reagents include palladium and oxygen (as referenced)
• Mechanistic idea:
  • Chlorine leaves
  • Hydrogen replaces it to generate an aldehyde such as butanal (example given).

5c) Esters → aldehydes

• Starting point: an ester (with a carbonyl-containing ester group)
• Conditions/components emphasized:
  • A catalyst and temperature (not fully enumerated; includes an aluminum-related component referenced earlier)
  • Water added (“hydrate” step)
• Outcome:
  • Oxygen-containing parts are removed/shifted so the reaction leaves the aldehyde.
• Example logic shown:
  • The ester’s oxygen-containing “bottom part” is removed while the aldehyde-forming carbon chain remains, including the hydrogen placement logic.

Active break (class activity instructions)

An in-class movement routine is included:

• Rules:
  • “1” = one clap
  • “2” = two jumps
  • “3” = move head three times
  • “4” = run in place
• Sequence examples performed:
  • “1 clap”
  • “2 jumps”
  • “3 head movements”
  • “4 run in place”
• The class repeats the sequence as prompted, then does inhale/exhale breathing.

Review/checkpoint activity: identifying reaction types (final learning check)

Students identify reaction types based on two reaction sketches shown on screen:

1. Aromatic ring (benzene) + activating/halogen + carbon monoxide + HCl + AlCl₃

   • Identified as Freidel–Crafts / Freidel–Crafts-related formylation logic used to produce an aldehyde.
   • Notes explicitly mentioned:
     • “Freidel Crush” is referenced as a key reaction label in the instructor’s phrasing.
     • Freidel–Crafts acylation is typically for ketones, and the aldehyde outcome depends on reaction variation/activator positioning.

2. A carbon chain with CH₂ bonded to an OH (alcohol precursor) + catalysts

   • Identified as oxidation of primary alcohols producing an aldehyde.

• Closing statement:
  • Reactions are “not difficult” if you track:
    • the starting material,
    • the expected product,
    • and the required conditions/catalysts.

Speakers / sources featured

• Primary speaker: the teacher/instructor narrating the class (name not provided in subtitles).
• Program/brand reference (source): “Monte Rosales” (mentioned as the class/education context).