chemistry introduction to organic chemistry

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Nomenclature

molecular formula - number of each atom present in one molecule of the compound

general formula - used to calculate molecular formula by substituting n for number of carbon atoms

structural formula - how atoms are arranged and shows functional groups

displayed formula - shows every bond in the arrangement of atoms

skeletal formula - shows bonds between carbons but not atoms

Naming organic compounds

  • the size and shape of carbon skeleton
  • the presence of functional groups
  • the position of functional groups

functional group - atoms responsible for chemical reactions

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homologous series

A group of molecules with the same functional group but a different number of -CH2 groups

Characteristics of a homologous series

  • same general formula
  • differs by -ch2 group
  • same chemical properties
  • length affects physical properties
  • melting and boiling point differ
  • increased length increase melting point due to increase strength of Van Der Waals
  • increased branching decreases melting point so less packed so weaker forces
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Homologous series extended

Alkenes    c=c     -ene

Alcohols    c-o-h    -ol or hydroxy-

Halogenoalkane      c-halogen     Chloro/Bromo/Iodo-

Aldehydes     cho c-h c=o     -al

Ketones      c=o     -one or  -oxo

Carboxylic acid     cooh c=o c-o-h    -oic acid

Nitriles    -c-=N    -nitrile

Amines    c-n=h2      -amine    amino-

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naming homologous series

  • identify functional group and homologous series
  • select longest carbon chain containing functional group
  • number of carbon atom to give lowest number for functional group
  • any addition functional groups as prefixes and numbered
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Alkanes and Alkenes

Alkanes

CnH2n+2

only c-c so are saturated

alkanes with 4 or more C display structural isomerism as they can be straight or branched

Alkenes

CnH2n

c=c so unsaturated

c=c has 2 different types of bonding due to overlap of orbitals. 1st bond is a signa and 2nd is sideways and is a Pi bond. Pi bond restricts rotation of bond meaning stereoisomerism is achieved

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Halogenoalkanes

Alkanes + halogen

Alphabetically numbered

  • number of C atoms bonded to main chain
  • Di, tri or tetra for the number of halogen atom
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Free radical substitution

A radical is an atom or molecule with an unpaired electron. they are caused by homolytic fission (breaking of a covalent bond) Cl2 -> 2CL'

CL' + CH4 -> HCL + 'CH3

chlorine radical + methane -> hydrogen chloride + methly radical

Initiation (rapid homolytic fission)

Propagation (reacts with molecules)

Propagation 2 (more reactions)

Termination (total number of radicals stays the same)

Single headed arrow is one electron moving Double headed arrow is two electrons moving

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Isomerism

Structural: same molecular formula different arrangement of atoms

  • chain (branched) - different skeletal arrangement (all molecules with more than 4 carbons)
  • position - different placement of functional group (only alkenes (4+), halogenoalkanes (3+), alcohols (3+))
  • functional group - different functional group ((alkenes and cycloalkanes)Carbonyls,alkenols and cycloalcohols(amines)(amides)(esters and carboxylic acids))

stereoisomerism

  • geometric e-z (higher priorities on opposite sides is E and higher priorities on same side is Z) use of the Cahn-Ingold-Prelog rules
  • optical
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