Organic Chemistry test 3

• Alcohols


  • Importance
  • Structure
  • Name
  • Physical properties
• Aliphatic alcohols

  • OH group connected to an alkyl, alkenyl or alkynyl group
  • Structure of alkanol/alkyl alcohol resembles structure of H2O, with an alkyl group replacing one of the H atoms of H2O
  • Both H2O & methanol have sp3 hybridised O atoms
• Classification of alcohols


  • Primary (1o): OH attached to 1o carbon - RCH2-OH
  • Secondary (2o): OH attached to 2o carbon - R2CH-OH
  • Tertiary (3o): OH attached to 3o carbon - R3C-OH
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• In general, the boiling point of a series of isomers decrease with branching. The more nearly spherical a compound becomes, the less surface area it has relative to a straight chain compound of the same molecular weight and functional group type. A smaller surface area allows fewer Van der Waals interactions. In addition, branching in alcohols makes it more difficult for hydroxyl groups to approach each other to form hydrogen bonds. A given volume of 2-methyl-2-propanol therefore contains fewer hydrogen bonds than the same volume of 1-butanol, and less energy is needed to break them in boiling.
• Major classes of Organic Compounds (macromolecules)

  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
• Carbohydrates


  Previously defined as hydrates of carbon, currently defined as polyhydroxy aldehydes or ketones
• Carbohydrates


  • Contain hydroxyl groups and aldehyde or ketone groups
• Functions of Carbohydrates


  • Immediate energy supply e.g. glucose
  • Chemical energy stores e.g. starch, glycogen
  • Structural/support e.g. cellulose
  • Biosynthesis of nucleotides
• Classification of Carbohydrates


  • Monosaccharides
  • Oligosaccharides
  • Polysaccharides
• Monosaccharides


  Simplest carbohydrates, containing 3-9 C atoms, cannot be hydrolysed to simpler sugars, common ones contain 5 and 6 C atoms
• Aldoses


  Derived from glyceraldehyde
• Ketoses


  Derived from dihydroxyacetone
• Major classes of Organic Compounds

  • Lipids
  • Proteins
  • Nucleic acids
• Carbohydrate Nomenclature


  • Suffix -ose to designate a carbohydrate
  • Prefix aldo- and keto- designate the nature of the carbonyl group
  • Number of carbon atoms in the monosaccharide is given by using tri-, tetr-, pent-, hex- etc
• Lipids


  Organic compounds which are relatively insoluble in water (hydrophobic) but freely soluble in non polar solvents
• Important aldoses


  • D-ribose
  • D-glucose
  • D-galactose
• Important ketoses


  • D-ribulose
  • D-fructose
• Lipids


  • Major structural components of cell membranes
  • Storage and transport of metabolic fuel
  • Provide protective surface coatings for organs
  • Insulation and lubrication
• Stereochemistry of Carbohydrates


  D and L sugars exist, Isomers exist with the same chemical constitution but a different arrangement of atoms
• Lipid Classification


  • Phospholipids
  • Glycolipids
  • Steroids
  • Hormones
• Fatty acid structure and nomenclature


  • Long hydrocarbon chains with terminal carboxylic acid groups
  • Most have an even number of C atoms and 12-20 carbons
  • May be saturated or unsaturated
• Oligosaccharides


  Contain 2-10 sugar units joined by glycosidic bonds, e.g. disaccharides, trisaccharides
• Phenols


  Aromatic alcohols containing an OH group connected to a C in a benzene ring
• Common disaccharides


  • Maltose (2 glucose units)
  • Sucrose (glucose and fructose)
  • Lactose (glucose and galactose)
• Phenols


  • phenol (hydroxybenzene)
  • resorcinol (3-hydroxyphenol)
  • 4-hexylresorcinol (4-hexyl-3-hydroxyphenol)
• Fatty acid types


  • Saturated fatty acids: no double bonds (e.g. palmitic acid (C16:0) and Stearic acid (C18:0))
  • Monounsaturated fatty acids: only one C-C double bond (e.g. Oleic acid (C18:1))
  • Polyunsaturated fatty acids: two or more C-C double bonds (e.g. linoleic (C18:2) and arachidonic acid (C20:4))
• Glucose


  Exists primarily as a six membered ring called pyranose
• trans-Resveratrol


  Naturally occurring phenol with reported anti-cancer, anti-inflammatory, blood-sugar-lowering and beneficial cardiovascular effects, but uncertain effect on lifespan
• Fatty acid nomenclature


  • In IUPAC nomenclature, carboxyl carbon is C-1
  • Common nomenclature: α, β, γ … furthest carbon from carboxyl group is ω. α β
• Maltose

  2 D-glucose residues linked via an α 1,4 glycosidic bond
• Structure of phenols


  • O is sp3 hybridised & the aryl/aromatic C is sp2 hybridised
  • Phenol is from "phenyl alcohol"
• Triacylglycerols


  • Composed of 3 fatty acid residues esterified to glycerol (3-carbon sugar alcohol)
  • Main constituent of body fat in humans and animals
• Acidity and basicity of phenols


  • Phenols are weak Bronsted bases
  • Phenols are weak Bronsted acids, can transfer H+ to H2O to a small extent producing a phenoxide ion (ArO-)
  • Phenols (pKa ~10) are much more acidic than alcohols (pKa ~16) due to resonance stabilisation of the phenoxide ion
• Polysaccharides


  • High molecular weight polymers, usually >20 monosaccharide units, hydrolysed to many monosaccharides, up to thousands, serve as energy stores and have structural functions
• Amino acids


  • The basic constituents of peptides and proteins
  • They are carboxylic acids with an amine functional group
• Organic Chemistry, UNAM School of Medicine
• Polysaccharides


  • Starch (major carbohydrate reserve of most plants)
  • Glycogen (animal storage carbohydrate, mainly in liver, muscle)
  • Cellulose (principal cell wall component of higher plants)
• Reduction of sugars


  1. Sugars are reduced to sugar alcohols by reacting with H2 under pressure in presence of nickel catalyst

  2. Reduction of glucose forms sorbitol

  3. Xylose reduction produces xylitol
• Amino acid classes


  • Neutral amino acids
  • Polar/non polar
  • Acidic
  • Basic