week 2 - functional groups and chirality

• drawing molecules

  • structural formula = lewis
  • skeletal formula = line
  • semi structural = condensed

  A) line

  B) lewis

  C) condensed

  
• types of carbon atoms

  • Primary: a carbon bonded to 1 other carbon
  • Secondary : a carbon bonded to 2 other carbons
  • Tertiary: a carbon bonded to 3 other carbons
  • Quaternary: a carbon bonded to 4 other carbons

  A) quarternary

  B) primary

  C) secondary

  D) tertiary

  
• functional group definition

  • “An atom or group of atoms within a molecule that shows a characteristic set of physical and chemical properties”
• types of functional groups

  A) ether

  B) aldehyde

  C) ketone

  D) imine

  E) nitrile

  F) thiol

  G) azo

  
• alkane

  • saturated hydrocarbons
  • shape: tetrahedral carbon, all bond angles are ~109.5

  
• alkene

  • unsaturated hydrocarbon
  • shape: trigonal planar at carbon, all bond angles are ~120

  
• naming compounds

  • prefix: tells us number of C's in parent chain
  • infix: tells us nature of carbon-carbon bonds
  • suffix: tell us class of compound (ie. functional group)

  A) infix

  
• dipole dipole interactions

  • the attraction between the positive end of one dipole and the negative end of another dipole
  • ie. slightly negative --- slightly positive
• amines

  • Primary: a nitrogen bonded to only 1 other carbon
  • Secondary: a nitrogen bonded to 2 other carbons
  • Tertiary: a nitrogen bonded to 3 other carbons
  • Quaternary a nitrogen bonded to 4 other carbons

  A) quarternary

  
• functional group conversions

  • primary alcohol -> aldehyde -> carboxylic acid
  • secondary alcohol -> ketone
  • tertiary alcohol

  
• alcohols

  • primary: the OH is bonded to one carbon atom
  • secondary: the OH is bonded to 2 carbon atoms
  • tertiary:the OH is bonded to 3 carbon atoms
• cool

  • the difference between morphine, heroin and codeine is the functional groups attached to them

  A) acetate

  
• isomers

  • same molecular formula but different arrangement in space

  constitutional isomers (ie. structural isomer)

  • same molecular formula but different skeleton of molecule (eg. butane to methyl propane)

  stereo isomers

  • same molecular formula but have different 3D orientation in space
  • geometric (cis/trans) and optical (enantiomers/diastereomers)
• isomers

  • same molecular formula but different arrangement in space

  constitutional isomers (ie. structural isomer)

  • same molecular formula but different skeleton of molecule (eg. butane to methyl propane)

  stereo isomers

  • same molecular formula but have different 3D orientation in space
  • geometric (cis/trans) and optical (enantiomers/diastereomers)

  A) constitutional

  B) diastereomers

  C) enantiomers

  
• geometric isomers

  • they have a fixed orientation (ie. no rotation around the C=C)


  E and Z isomers

  • more specific than cis/trans
  • priority rule (CIP) : depends on the atomic number of the atom

  1. highest atomic number = highest priority
• geometric isomers

  • they have a fixed orientation (ie. no rotation around the C=C)

  E and Z isomers

  • more specific than cis/trans
  • priority rule (CIP) : depends on the atomic number of the atom

  1. look at the 2 groups on each C atom SEPARATELY
  2. if the group is not one atom, but many, follow the chain one by one
  3. highest atomic number = highest priority
  4. if the highest priority groups are opposite, it is E
  5. if the highest priority groups are same side, it is Z

  A) cis

  B) trans

  C) Z

  D) E

  E) Z

  F) E

  
• chirality

  • if a molecule is identical to its reflection, it is achiral
  • if a molecule is not identical to its reflection, it is chiral
  • eg. hands are chiral since its reflection is not identical to the original (ie. its mirror image is non-superimposable)

  A) chiral

  B) achiral

  
• chirality

  • if a C has 4 different groups attached to it, it has a stereogenic centre, thus the molecule will most likely be chiral
  • enantiomer = a pair of chiral molecules
  • Enantiomers do not differ in physical characteristics, but interact differently with plane polarized light

  A) stereogenic

  
• achiral

  • has a plane of symmetry
  • an object and its mirror image are superimposable

  
• naming enantiomers

  1. locate the chiral/stereogenic centre
  2. assign priority 1-4 based on highest atomic number (if same, then go to next atom connected to it)
  3. orient the lowest priority group points away from you (usually H) and the other 3 groups towards you
  4. reading from group 1-3, if the order is clockwise (R - sinisiter - right) if the order is anticlockwise (S - sinister - left)

  A) R

  B) S

  
• enantiomers...

  A) 256

  
• Stereoisomers

  • R will always invert to S
  • S will always invert to R
• diastereoisomers

  • stereoisomers that are not mirror images of each other (ie. cannot be superimposed)
  • not a pair of enantiomers

  
• enantiomer

  • when all chiral centres change and there is a lack of symmetry

  mesoisomer

  • when all chiral centres change and there is a line of symmetry

  diastereoisomer

  • when some chiral centres change but not all
• enantiomers and biology

  • enzymes can distinguish between their enantiomers
  • this is because the enantiomer's binding site will not fit the enzyme's active site

  
• reminder

  A) away

  B) towards

  C) plane

  
• the only exception to the 2^n rule

  • mesoisomers
• stereoisomers summary

  • should be 2^2=4 stereoisomers, but due to meso, there's 3 stereoisomers
  • 1 & 2/4 are diastereoisomers (not mirror images)
  • 1 & 3 are mesoisomers (symmetry plane)
  • 2 & 3 are diastereoisomers (not mirror images)
  • 2 & 4 are enantiomers (mirror images)
  • 3 & 4 are diastereoisomers

  
• table

  A) non-superimposable

  B) non-superimposable

  C) yes

  D) no

  E) superimposable

  F) mirror image

  
• enantiomers

  • if their R and S configuration is exact opposite
  • eg. R&S enantiomer = S&R