OCR Chemistry 2.1.1 Nomenclature - naming of organic compounds

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  • Created by: Kayleigh
  • Created on: 02-03-14 16:34

Nomenclature

Naming of organic compounds involves following these steps:

1) count the number of carbon atoms in the longest unbranched chain to give the main root of the name:

  • 1 Carbon = meth
  • 2 Carbons = eth
  • 3 = prop
  • 4 = but
  • 5 = pent
  • 6 = hex
  • 7 = hept
  • 8 = oct
  • 9 = non
  • 10 = dec

2) if the atoms are arranged in a ring then put cyclo before root name e.g. cyclohex

3) if it is saturated (single C-C bonds only) -an- comes after root name

if it is unsaturated (double C=C bond/s) -en- comes after root name

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Nomenclature continued...

4) for functional groups a prefix/suffix is used (you only need to know these ones). R represents a variable group:

  • alkane -ane or -yl C-C
  • alkene -ene C=C
  • halogenoalkane fluoro-/chloro-/bromo- R-Hal
  • alcohol -ol or hydroxy- R-O-H
  • ketone -one R-C-R (O double bonded to C in ketone, aldehyde, carboxylic acid and ester but unable to show this using a keyboard)
  • aldehyde -al R-C-H
  • carboxylic acid -oic acid R-C-OH
  • ester -oate R-C-O-R

5) if no functional group present, add e onto the end of the name

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6) if the carbon chain is branched (meaning there are further side carbon chains attached to the longest carbon chain), then count how many carbons in the side carbon chain:

  • 1 carbon = methyl
  • 2 = ethyl
  • 3 = propyl
  • 4 = butyl

7) a number is used to indicate the position of a side chain or functional group. Number the carbon atoms from either side of the chain, making sure that the functional group/side chain is on the lowest numbered carbon atom

8) if there is a double bond then a number before the -en- indicates this

9) aldehydes, carboxylic acids and nitriles are always regarded as containing carbon number 1 in the chain

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10) if there is the same functional group more than once add a prefix:

  • twice di-
  • three times tri-
  • four times tetra-

11) positions and manes of functional groups must be in alphabetical order

12) if there are 2 or more functional groups this usually requires suffixes to be used. The ending for a carboxylic acid takes priority over an aldehyde or ketone. Then alcohol has the lowest priority

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