MIDTERMS

• Recrystallization


  1. Dissolve solid in hot solvent mixture

  2. Cool solution slowly

  3. Decreased solubility at lower temperature forms crystals

  4. Small seed crystal forms initially and grows layers
• Fractional crystallization


  • Important method for purification of compounds from a mixture
  • Depends on the inherent character of the compound which forms crystals at the point of supersaturation in solvent
• Procedure for recrystallization


  1. Mix aniline and water

  2. Slowly add acetic anhydride

  3. Cool in ice bath

  4. Filter and dry crude acetanilide

  5. Dissolve crude acetanilide in recrystallizing solvent and heat
• Acetanilide


  • C6H5NH(COCH3)
  • Synonyms: N-phenylacetamide, Acetanil, 2-Acetanilide, Acetic acid anilide, CAN, Ethananilide, Acetylaniline, Acetylaminobenzene, Antifebrin, N-Acetylaniline, Acetaminobenzene

  
• Recrystallization (Crystallization)


  Purification procedure which requires solubility of impure solid in heated solution and crystallization upon cooling
• Industrial use of acetanilide

  • Used as an inhibitor of peroxides and stabilizer for cellulose ester varnishes
  • Used as an intermediate for synthesis of rubber accelerators, dyes, dye intermediates, and camphor
• Pharmaceutical use of acetanilide


  Phenylacetamide structure shows analgesic and antipyretic effects, but acetanilide is not used directly due to causing methemoglobinemia
• Acetanilide is converted to a phenolic metabolite in the body that gives it an analgesic effect, but some is converted to aniline which is toxic

  
• Organic chemistry


  Study of carbon compounds (except CO, CO2, carbonates, hydrogen carbonates, carbides, and cyanides) obtained from natural sources or synthesized in laboratories
• Differences between organic and inorganic compounds

  • Organic: Carbon compounds, covalent bonds, low MP and BP, most burn in oxygen, soluble in non-polar solvents, non-electrolytes, large molecules
  • Inorganic: Metals in salts and oxides, ionic or polar bonds, high MP and BP, few burn in oxygen, most soluble in polar solvents, electrolytes, small molecules

  
• Functional group


  An atom or group of atoms that effectively determines the chemical properties of an organic compound

  
• Homologous series


  Physical properties change gradually, with longer carbon chains having greater attractive forces between molecules, higher MP, BP, and density
• Factors affecting physical properties of organic compounds

  • Structure of functional group (dipole moment, hydrogen bonding)
  • Length of carbon chains (London dispersion forces)
• Ethanol


  Also called ethyl alcohol, chemical formula CH3CH2OH, an alcohol with a hydroxyl group

  
• Uses of ethanol


  • Thermometer for temps below Hg's freezing point
  • Antifreeze in automobile radiators
  • Make alcoholic beverages
  • Burn in automobile engines mixed with gasoline
  • Reduce air pollution in exhaust gas
• Ethanol in the brain

  • Affects neurotransmitters like GABA, toxic so body disposes of it immediately
  • Acts as a depressant that affects the CNS and suppresses brain functions, but moderate amounts can stimulate and relax
• Phenol


  Polar, can hydrogen bond, water insoluble, stronger acids than water, dissolve in 5% NaOH but not 5% NaHCO3

  
• Cyclohexane


  Clear colorless liquid with petroleum-like odor, used as solvent and to make other chemicals, miscible with various organic solvents
• Benzoic acid


  Colorless crystalline solid, simple aromatic carboxylic acid, used medicinally in Whitfield's ointment for fungal skin diseases
• Ethyl acetate


  Most popular ester from ethanol and acetic acid, volatile, relatively non-toxic and non-hygroscopic, used as solvent in surface coatings and thinners

  
• Ethyl ethanoate


  Commonly abbrev. EtOAc or EA
• Ethyl ethanoate


  • Most popular ester from ethanol and acetic acid
  • Volatile, relatively non-toxic and non-hygroscopic
  • Molecular weight: 88.10
  • Melting point: -83.6 C
  • Boiling point: 77.15 C

  
• Ethyl Acetate manufacture


  Esterification

  
• Uses of Ethyl Acetate


  One of the most popular solvents used in surface coating and thinners manufacture such as nitrocellulose lacquers, varnishes and thinners

  
• Alkanes have very similar characteristics in terms of intrinsic property as they are observed to be colorless and clear
• Cyclohexane, ethanol, ethyl acetate, and ethyl amine were observed to be polar compounds

  
• Phenol and benzoic are acidic, while ethyl amine is basic
• Cyclohexane, ethanol, ethyl acetate, and ethyl amine were observed to be flammable with varying flame colors and intensity

  
• Toluene


  • A liquid, which is colorless, water-insoluble and smells like paint thinners
  • A mono-substituted colorless liquid, consisting of a CH3 group that is attached to a phenyl group

  
• Toluene


  • Precursor to other chemicals like polyurethane foam, trinitrotoluene (explosive), and synthetic drugs
  • Can be used as fuel in internal combustion engines as gasoline fuel
  • Used as a solvent for carbon nanomaterials, nanotubes and fullerenes
• Baeyer's test


  A laboratory test to identify the presence of a double bond in the given unsaturated compound
• Cyclohexene is positive for active unsaturation, confirming that it has double bond

  
• Bromine test


  Used to detect the presence of unsaturated compounds of alkene and alkyne

  
• Bromine and carbon tetrachloride is used, only reactive with CYCLOHEXENE

  
• Nitration test


  Used to determine aromaticity
• Benzene and Toluene reacts with Nitration test

  
• Basic oxidation test


  Used to determine active unsaturation
• Aromatic compounds


  • Follow the 4n+2 rule (HUCKEL'S RULE)
  • Sp2 hybridized
  • Conjugated double bonds

  
• Organic halides


  • Organic compounds containing a halogen atom bonded to a carbon (C) atom
  • Not flammable
  • Usually sp3 hybridized

  
• Reactivity of organic halides

  • Can be differentiated via a substitution reaction with a nucleophile, depending on which reactant molecule (nucleophile or organic halide) is involved in the rate-determining step
  • If the rate of the reaction is dependent on the organic halide, the reaction is unimolecular: SN1
  • If the rate of reaction is dependent on both the organic halide and the nucleophile, the reaction is bimolecular: SN2