Organic Chemistry Chapters 22-23

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Organic ChemistryChapters 22-23
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Straight Chain Alkanes

• An alkane is a saturated hydrocarbond
• i.e. it has no double bonds, and every carbon has
  the maximum possible number of hydrogens
• CH4 methane
• CH3CH4 ethane
• CH4 CH3CH4 propane
• CH4CH3CH3CH4 butane
• Beyond 4 carbons, standard Greek prefixes are
  used
• E.g. 5C pentane, 6C hexane

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Branched Chain Alkanes

• Identify the main chain.
• It will have the highest number of carbon atoms
  in it
• Name the main chain using standard conventions
• Number the carbons in the main chain from left to
  right
• Identify which carbon the secondary chain
  branches from
• Identify the number of carbons in the secondary
  chain
• Name the secondary chain
• The final name is the number you identified in
  step 4, followed by the name of the secondary
  chain with the ending yl, followed by the name
  of the main chain.
• E.g. 2-methylpropane indicates is the name for
  the molecule

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Cycloalkanes

• Identify the number of carbons in backbone of the
  ring.
• Use the carbon number to name the ring, adding
  the prefix cyclo to indicate that it is a ring
• E.g. the smallest ring possible is cyclopropane,
  which has 3 carbons in the main ring
• Number the carbons in the main ring, starting at
  the top and working clockwise.
• If any substituent groups branch off the main
  ring, identify which number carbon the branch
  from
• Name the substituent group, remembering to add
  the suffix yl to the stem
• The final name is the number you identified in
  step 3, followed by the name of the secondary
  chain with the ending yl, followed by the name
  of the main ring.
• E.g. 2-methylcyclopropane indicates is the name
  for the molecule

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Alkenes

• An alkene is unsaturated because it contains at
  least C-C double bond.
• i.e. it does not contain the maximum number of
  hydrogen atoms around every carbon atom
• Use the same naming convention as alkanes, but
  use the ending ene instead of ane.
• Also, by numbering the carbons, indicate the
  number of the first C in the C-C double bond.
• So, 2-butene is the name of the molecule below.
• N.B. Because there must be a C-C double bond, the
  smallest possible alkene is ethene.

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Branched-Chain Alkenes

• Number the carbons in order to give the lowest
  number possible to the carbon containing the
  double bond.
• Identify the carbons with substituents attached.
• Identify the substituents.
• See page 713, problem 22-3 for an example

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Alkynes

• Alkynes have at least one C-C triple bond, and
  are therefore also unsaturated.
• Alkynes use the same naming conventions as
  alkenes, but use the yne ending instead of ene.

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Isomers

• Isomers have the same molecular formula, but look
  different.
• Structural isomers are bonded in different
  orders.
• E.g. pentane, 2-methylbutane, and
  2,2-dimethylpropane are all C5H12 molecules, but
  they have 5, 4, or 3 carbons in their main
  chains, respectively, and 0, 1, or 2 methyl
  substituent groups, respectively.
• Stereoisomers have the same bonding order, but
  are arranged differently in space. Stereoisomers
  are designated cis- or trans-.
• Optical isomers have the same bonding order, but
  exhibit chirality. This means that they are
  mirror images of each other and bend light
  clockwise (D-isomers) or counterclockwise
  (L-isomers)

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Aromatic Aliphatic Hydrocarbons

• Aromatic ring
• An exceptionally stable planar ring of atoms with
  resonance structures that consist of alternating
  double and single bonds, e. g. benzene
• Aromatic compound
• A hydrocarbon compound containing an aromatic
  ring.
• Aromatic compounds have strong, characteristic
  odors.
• Aliphatic Hydrocarbons
• A hydrocarbon compound lacking a ring structure

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Carcinogens

• Carcin cancer
• Gen create
• A carcinogen, therefore, causes cancer
• Many of the aromatic compounds are known
  carcinogens, others are suspected.

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Fractionating Petroleum

• All aromatic and aliphatic compounds are
  currently obtained from fossil fuels
• The most common source of hydrocarbons is
  petroleum
• Raw petroleum has gt 1000 different compounds in
  it and is called crude oil
• It is therefore separated via fractional
  distillation into its simpler components.
• Industry can then take the simpler components to
  create gasoline, plastics, shampoos, contact
  lenses, and the wide variety of other
  hydrocarbon-based consumer products that all
  originate from petroleum.

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Functional Groups

• A functional group in an organic molecule is an
  atom or molecule that always reacts in a
  predictable manner
• The addition of functional groups to a basic
  hydrocarbon always produces a substance with
  distinct properties from the basic hydrocarbon

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Halides

• Halides
• Any of the Group 7A elements that are attached to
  a hydrocarbon
• Alkyl halides are organic compounds containing a
  halogen covalently bonded to an aliphatic carbon
  atom
• Aryl halides are organic compounds containing a
  halogen covalently bonded to an aromatic carbon
  atom
• 1. The simplest halogenoalkane is exemplified by
  chloromethane (methyl chloride)
• 2. to 7. Are examples of multi-substituted
  halogenoalkanes based on methane
• 2. trichlorofluoromethane, (CFC-11, a
  chlorofluorocarbon or CFC)
• 3. dichlorodifluoromethane, (CFC-12)
• 4. difluoromethane (a hydrofluorocarbon or HFC,
  methylene difluoride)
• 5. tribromomethane
• 6. tetrachloromethane, (carbon tetrachloride)
• 7. chlorodifluoromethane, (HCFC-22 a
  hydrochlorofluorocarbon or HCFC)

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Carboxylic Acids

• The primary suffix name for a carboxylic acid is
  based on the "longest carbon chain name " "oic
  acid" for the COOH acidic bond system
• methanoic acid (formic acid)
• HCOOH
• ethanoic acid (acetic acid)
• CH3COOH
• Propanoic acid (propionic acid)
• CH3CH2COOH

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Alcohols

• Alcohols have the hydroxy group OH attached to at
  least one of the carbon atoms in the chain.
• If the OH group is directly attached to a benzene
  ring , it is classified as a phenol.
• The primary suffix name is ..ol for alcohol and
  so for the longest carbon chain (alkanol) the
  names are based on
• 1 carbon, methanol
• 2 carbons, ethanol
• 3 carbons, propanol
• 4 carbons, butanol, etc.
• The positions of the substituent alkyl (or other)
  groups are denoted by using the lowest possible
  numbers for the associated carbon atoms in the
  main chain.
• If there is more than one 'type' of substituent
  eg using the prefixes methyl and ethyl.. etc.,
  they are written out in alphabetical order (di,
  tri are ignored in using this rule).

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Alcohol Classification

• Alcohols are classified according to the
  atoms/groups attached to the carbon of the
  hydroxy group
• Primary alcohols have the structure R-CH2-OH, R
  H, alkyl, aryl etc. ie apart from methanol they
  have one alkyl/aryl group attached to the C of
  the C-OH group.
• Secondary alcohols have the structure R2CH-OH, R
  alkyl or aryl etc. ie they have two alkyl/aryl
  groups attached to the C of the C-OH group.
• Tertiary alcohols have the structure R3C-OH, R
  alkyl or aryl etc. ie they have three alkyl/aryl
  groups attached to the C of the C-OH group.
• Ethers are named on the basis of the longest
  carbon chain with the O-R or alkoxy group, eg
  methoxy CH3O- or ethoxy CH3CH2O- etc. treated as
  a substituent group.
• Diol, triol and Cycloalcohol (cycloalkanols)
  structures and names are on a separate web page
• Some 'old' names are quoted in () though their
  use should be avoided if possible but many still
  used - just put one into GOGGLE!.

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Alcohol Examples

• Methanol
• CH3OH
• Ethanol
• CH3CH2OH
• Propan-1-ol
• CH3CH2CH2OH
• Propan-2-ol
• CH3CH(OH)CH3

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Ethers

• Ethers are formed from the condensation of 2
  alcohols
• R-OH R'-OH R-O-R' H2O
• This is called a dehydration synthesis reaction
• N.B. R and R' represent organic groups.
• Methoxymethane (methyl ether)
• CH3OCH3
• Ethoxyethane (ethyl ether)
• CH3CH2OCH2CH3

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Esters

• An ester is a compound formed from an acid and an
  alcohol .
• In esters of carboxylic acids , the -COOH group
  of one hydrocarbon and the -OH group from another
  hydrocarbon lose a water and become a -COO-
  linkage
• R-COOH R'-OH R-COO-R' H2O

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Primary and Secondary Amines

• An amine is an organic compound that contains a
  nitrogen atom bound only to carbon and possibly
  hydrogen atoms.
• Primary Amines  these have two hydrogen atoms
  and one alkyl or aryl group attached to the
  nitrogen to form the amine or amino group -NH2.
• Methylamine
• CH3NH2
• 2-aminopropane
• CH3CH(NH2)CH3
• Secondary Amines these have one hydrogen atom
  and two alkyl or aryl groups attached to the
  nitrogen
• Dimethylamine
• (CH3)2NH
• Ethylpropylamine
• Diphenylamine

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Tertiary Amines

• Tertiary amines have no hydrogen atom and three
  alkyl or aryl groups attached to the nitrogen
• Trimethylamine
• Ethyldimethylamine
• N,N-dimethylphenylamine

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Carbonyl Compounds

• Aldehydes and ketones are a group of compounds
  containing the carbonyl group, CO.
• Aldehydes always have a hydrogen atom attached to
  the carbon of the carbonyl group, so the
  functional group is -CHO (see diagram above).
• The functional group is shown by using 'al' in
  the suffix part of the name eg methanal, ethanal,
  propanal etc.
• Ketones always have two carbon atoms attached to
  the carbon atom of the carbonyl group, so the
  functional group is C-CO-C (see diagram above).
• The functional group is shown by using 'one' in
  the suffix part of the name
• eg propanone, butanone, hexan-3-one etc.
• The substituent numbers are based on giving the
  CO carbon the lowest number
• eg 2-methylbutanal ('al' position 1).
• The number position of the CO group in ketones
  needs to be specified for carbon chains of over
  4, or less, if substituents are present
• eg 3-methylbutan-2-one, heptan-2-one,
  heptan-3-one and heptan-4-one (there is no
  heptan-1-one, this is heptanal!).
• For the same 'carbon number', aldehydes and
  ketones are structural and functional group
  isomers CnH2nO.

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Aldehyde Examples

• Methanal (formaldehyde)
• HCHO
• Ethanal (acetaldehyde)
• CH3CHO
• 2-methylpropanal
• CH3CH(CH3)CHO

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Ketone Examples

• Propanone (acetone)
• CH3COCH3
• Butanone (methyl ethyl ketone)
• CH3COCH2CH3
• 1-Phenylethanone

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Amides

• An amide is an organic compound that contains a
  carbonyl group bound to nitrogen, also known as
  an acid amide.
• Naming The primary suffix name for an amide is
  based on the "longest carbon chain name"
  "amide" for the CONH2 bond system eg methanamide,
  ethanamide etc.
• Methanamide (formamide)
• HCONH2
• Ethanamide (acetamide)
• CH3CONH2
• Benzenecarboxamide (benzamide)
• C6H5CONH2

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Doc Browns Web Site

• http//www.wpbschoolhouse.btinternet.co.uk/page04/
  page04.htm