Halogen Derivatives and Anesthetics

Halogen Derivatives

• Are organic compounds containing Carbon, Hydrogen and Halogens (F, Cl, Br, I).
• All are man-made or synthetic, this is why some of them can cause environmental issues
• Examples include: Polymers (Teflon, PVC), CFC's (freons), pesticides (DDT).

Anesthetics

• Compounds used in medicine to lower reception, making people unconscious, and to reduce the perception of pain.
• Old anesthetics include:
  • N₂O (laughing gas) which is a mild anesthetic.
  • CHCL or chloroform which is too toxic.
  • CH3-CH2-O-CH2-CH3 or ether which is .
• Ideal anesthetics should have low or no toxicity, strong anesthetic properties, and be a gas or liquid with a low boiling point so it can be inhaled easily.
• Halogeno-compounds can be a solution
  • The least toxic/weakest anaesthetic properties are with CH3CL
  • The strongest anaesthetic/most toxic properties are with CCl4

Halothane

• Has low-reacting inertness
• Has anaesthetic properties
• A higher boiling point.

Nomenclature of anesthetics

• Examples:
  • CL-CH-CH3 could be propan-2-ol
  • CH3-CH2-Cl could be ethoxyethane

Chemical Properties of Halogenoalkanes

• Halogenoalkanes containing Cl or Br are useful for producing organic compounds.
• The reaction mechanism relies on the properties of the C-Cl or C-Br bond.
  • These bonds are polar
  • Cl is more electronegative than C

Nucleophilic Substitution

• Negative particles, such as OH⁻, are attracted to the C atom, and replace the halogen.
• Nucleophiles that could be produced from a molecule include:
  • CH3COO⁻/H⁺ from CH3COOH,
  • NH2⁻/H⁺ from NH3,
  • CN⁻/H⁺ from HCN,
  • CH3CH2O⁻/ Na⁺ from CH3COONa,
  • and HO- from H2O.
• Example Reaction: CH3CH2Cl + NaOH(aq) → CH3CH2OH + NaCl

Saytzeff's Rule

• When eliminating a mole from an organic compound to form two possible products, the major product will have a hydrogen atom removed from the carbon with the fewest hydrogen atoms to begin with.

Alcohols, Phenols and Ethers

• Oxo-derivatives containing the -OH hydroxy group.
• Ethanol (CH3CH2OH) is the most common.
• Naturally produced through fermentation.

Nomenclature

• Examples:
  • CH3OH is methanol
  • CH3CH2-OH is ethanol
  • CH3-CH2-CH2-OH is propan-1-ol
  • CH3-CH(OH)-CH3 is propan- 2-ol
  • CH2(OH)-CH2 (OH) is ethane 1,2-diol
  • CH2(OH)-CH(OH)-CH2(OH) is propane -1,2,3- triol

Classification of Alcohols

• Monohydric indicates one -OH group, like in CH3-CH2-OH.
• Polyhydric:
  • Diols indicate two -OH groups, like in CH2(OH)-CH2(OH)
  • Triols indicate three -OH groups, like in CH2(OH) -CH(OH)- CH2(OH), also known as Propane - 1,2,3-triol or glycerol.
• Aliphatic compounds include CH2CH2OH + phenols
• Aromatic compounds include Benzyl alcohol + are not phenols

Monohydric Alcohols

• Primary alcohols have the structure CH₂CH₂CH₂CH₂C(H)-OH, example is Pentan-1-ol
• Secondary Alcohols: CH3 C(H)(OH)CH₂CH₃, exmaple is Pentan-2-ol
• Tertiary Alcohols: (CH3)₂C(CH₂CH₃)OH, example is 2-methylbutan-2-ol
• 'Zero alcohols': H-C(H,H)-OH
• C4H10):
  • Secondary: CH3CH2CH(OH)CH3 which is butan-2-ol
  • Primary: HOCH2CH2CH2CH3 which is butan-1-ol
  • Tertiary: CH3C(CH3)(CH3)OH which is 2-methylpropane -1-ol
  • Primary: CH3C(CH3)(CH3)OH which is 2-methylpropane-2-Ol

Physical Properties of Alcohol

• Alcohols can form H-bonds (strongest intermolecular forces), so they are liquids/solids with higher melting & boiling points than alkanes.
• Properties are affected by polar & non-polar parts of the molecule.
• Almond containing 1-2 atoms mix with H20 perfectly, but as C-atoms increase, their solubility in H2O decreases
• Physical properties increase with molecule size, especially the boiling point, due to Van Der Waals forces.
• Boiling points are higher than alkanes (alcohols also have hydrogen bonds).
• The non-polar carbon chain impacts properties more as molecular size increases, reducing the influence of the OH group.
• Alcohol solubility starts high in water (infinite) due to H-bonds, but larger C chains reduce polarity and solubility quickly.
• Ethanol & propan-1-ol make good solvents because of their non-polar part and H-bond-forming OH group. They can dissolve both polar and non-polar substances (e.g., in window-cleaning fluid, perfumes).
• An alcohol's viscosity greatly increases if it has more than one OH group (e.g., propane-1,2,3-triol (glycerol, glycerin)).

Chemical Properties of Alcohols

• Alcohols are amphoteric, acting as acids or bases based on conditions. Acids donate H+ ions, while bases accept H+ ions. Alcohols behave like water.
• eg: H2O + H₂O ⇌ H3O+ + OH
• Water is a very weak acid and base
• R - OH + R-OH ⇌ R-OH2+ + R-O

Alcohols as Bases

• Alcohols behave as bases when reacting with acids, e.g., H2SO4 (catalyst)
• 3 important reactions: Elimination, Ether formation, & Esterification
• CH3-CH2-O-H + H+(H₂SO₄) → CH3-CH2-O-H H

Elimination

• Reaction of almond with acid (H₂SO₄) in excess (or another dehydrating agent e.g: Al₂O₃):
• CH3-CH2-OH + H+(H₂SO₄) → H₂ + CH2=CH2

Ether Formation

• Takes place when alcohol is in excess
• CH3-CH2-OH + HO-CH2-CH3 + H+(H2SO4) → H2O + CH3-CH2-O-CH2-CH3, also know as ethoxy ethane/diethylether.

Oxidation

• Oxidising agents (oxidants):
  • Acidified potassium manganate (VII)-KMnO₄/H+ : When it oxidises something it changes from purple to colourless
  • Sodium dichromate (VI) – Na2Cr2O7: Yellow/orange turning → green
• Primary alcohols (R - CH₂- OH)
• The O comes from an oxidising agent
• The Propan-1-ol reaction is H-C-C-C-OH
• The Propanol end product is an aldehyde
• The Propanoic acid end product is a Carboxylic acid

Secondary alcohols (R₂– CH – OH)

• the propan -2-ol reaction is H-CC-C-H
• with a propanol (A ketone) end product

– Tertiary alcohols (R3- C - OH)

• 2-methylpropan-2-ol has NO REACTION
• This is because there are no H-atoms on the C with the OH group
• This means there is no colour change of the oxidising agent

This lesson covers halogen derivatives, organic compounds containing carbon, hydrogen, and halogens. It explains their synthetic nature and environmental impact, with examples like Teflon and DDT. The lesson also discusses anesthetics, highlighting the properties and risks of old and ideal anesthetic compounds.