Organic Chemistry : Ch. 19 by ikMM90y


									         Organic Chemistry : Ch. 9

 Organic chemistry is the
  branch of chemistry which
  deals with “carbon based”
 Carbon is an element
  which has the unique
  ability to bond long chains,
  rings, and react with other
  elements to form a variety
  of compounds.
               Carbon Compounds

 Carbon compounds are
  found in many forms :
  gases, aqueous, and solids.
 Carbon is recycled in
  nature by the carbon cycle.
 Carbon chains can be
  modified by reactions to
  form different type of
  carbon based (organic)
                   Story of Carbon
 Carbon is a major component
  of living things.
 Lipids (fats and oils), sugars,
  starches, proteins, DNA, etc.
  are composed of carbon,
  hydrogen, oxygen, nitrogen,
  and other atoms.
 Lipids, sugars, and starches
  are composed of carbon,
  hydrogen, and oxygen.
 Proteins are composed of
  carbon, hydrogen, oxygen,
  nitrogen, and sometimes
                    Story of Carbon
Some carbon compounds are not considered organic.

 Eg
 Oxides of carbon (CO2 , CO )
 Ionic compounds of carbon like carbonate, cyanide ions and
  carbides where carbon behaves like a negative ion.

 Not organic
 Sodium carbonate, hydrogen cyanide, calcium carbide
                  Story of Carbon

 When the oxygen,
  nitrogen, sulfur, and other
  atoms are removed by
  bacteria, what is left is a
  hydrocarbon ( Carbon and
  hydrogen only)
 These hydrocarbons are of
  mixed sizes, and are known
  as “crude oil” when
  recovered from the earth.     Hydrocarbons : C & H atoms
                    Story of Carbon
 Carbon atoms have four
  electrons in their outer
  energy level, and will want
  to covalently bond (share
  electrons) with itself and
  other atoms to form more
  stable chain and ring
 The crude oil contains a
  mixture of hydrocarbons
  including : butane(lighter
  fluid), gasoline, diesel,
  candle wax, etc.
                  Story of Carbon

 The hydrocarbons found in
  crude oil can be separated
  based upon their boiling
  points and refined or
 By adding substances to
  them a host of other
  organic compounds can be
  produced : (alcohols,
  esters, ethers, plastic,
  styrofoam, etc.)

 Hydrocarbons are a class of organic compounds
  which contain only carbon and hydrogen.
 Hydrocarbons are characterized as carbon chains,
  branched chains, and rings.
 Fossil Fuels are primary sources of hydrocarbons.
      These include Natural Gas, Crude Oil, Heavy Oil, Oil
       Sands, and Coal.
 Refining is the process that separates and purifies
  the mixtures

 Carbon has 4 valence electrons and will form 4
  covalent bonds with hydrogen. A line between
  carbon and another atom represents the sharing of 2
  electrons. Therefore every carbon in an organic
  compound needs 4 lines around it.
 Hydrocarbons with all single carbon bonds are
  described as the Alkanes.
             Families of Organic

 Organic compounds can be grouped into families by
  their common structural features
 We shall survey the nature of the compounds in a tour
  of the families in this unit.
 This basic family or series for hydrocarbons are the
  alkanes, compounds that contain only carbons and
  hydrogens, all connected exclusively by single bonds
 The chains of carbons can be rearranged to form
  different shapes with the same number and kinds of
  atoms. These are called isomers.
       Alkanes and Alkane Isomers

 Alkanes: Compounds with C-C single bonds and C-H bonds
  only (no functional groups)
 Connecting carbons can lead to large or small molecules
 The formula for an alkane with no rings in it must be CnH2n+2
  where the number of C’s is n
 Alkanes are saturated with hydrogen (no more can be added
 They are also called aliphatic compounds
               Naming Alkanes
Basic principles
 The name for an alkane is based on Greek root with
  the suffix –ane.
             Branched Hydrocarbons
 Hydrocarbons come in a variety of forms.
 Not all hydrocarbons are linear, some are branched and some are
 Branched hydrocarbons have a carbon “backbone” with “groups”
  attached to this backbone.
 To name these compounds you need to follow the basic rules
  below: (IUPAC)
 Find the longest carbon chain (backbone) and write its
  corresponding name.
 Identify the groups attached to this chain.
 Assign the carbons in the chain numbers, which make the “group”
  have the lowest number.
 Identify any double or triple bonds with the corresponding carbon
          Branched Hydrocarbons

 Branched hydrocarbons are
  found in crude oil and can
  also by synthesized by
  chemical reactions.
 Hydrocarbons with only
  single bonds are termed
  “saturated” hydrocarbons.
 Hydrocarbons with a
  double or triple bond are
  called “unsaturated”         Saturated hydrocarbon : Pentane
                   Naming Alkanes
Basic principles

 For branched hydrocarbons use the longest
  continuous chain for the root name.
                   Naming Alkanes
Basic principles

 Alkanes missing one H atom can have another
  hydrocarbon attached at the missing H point.
                   Naming Alkanes
Basic principles

 Specify the names of groups by numbering the
  C atoms starting at the end closest to the
       Naming Alkanes
Basic principles

  attached to the
  main chain are
  branches and
  here are the
  most common
  alkyl or
                   Naming Alkanes
Basic principles
 If a group occurs more than once use a prefix to
  show this. The numbers show the carbon where
  the group is attached. Use commas and dashes.

 Eg.    2,3-dimethylpentane
Naming Alkanes

 Diagram the following branched hydrocarbons:
a) 2 methyl, hexane   b) 2,2, dimethyl pentane

c) 2,3 dimethyl octane    d) 2,4 dimethyl 3-decene

  Cycloalkanes are alkanes that have carbon atoms that
   form a ring (called alicyclic compounds)
  Simple cycloalkanes rings of CH2 units, (CH2)n, or
  Structure is shown as a regular polygon with the number of
   vertices equal to the number of C’s (a projection of the
   actual structure)

cyclopropane   cyclobutane                  cyclohexane
               Naming Cycloalkanes
 Count the number of carbon atoms in the ring and the number in the
  largest substituent chain. If the number of carbon atoms in the ring is
  equal to or greater than the number in the substituent, the compound is
  named as an alkyl-substituted cycloalkane
 For an alkyl- or halo-substituted cycloalkane, start at a point of
  attachment as C1 and number the groups on the ring so that the second
  substituent has as low a number as possible.
 Number the substituents and write the name
 See text for more details and examples
               Drawing molecules

 You can use structural formulas as usual or
  condensed formulas or line formulas.


                                                   5               1
                                       7                   3
                                               6       4       2

Why is the above numbered incorrectly? What are their names?
          Hydrocarbons : Alkenes

 Carbon atoms have the ability to bond with other
  atoms with single, double, or even triple bonds.
 When carbon bonds to another carbon with a
  double bond, and only carbon and hydrogen atoms
  are in a compound it’s termed an alkene.
 Ethylene(ethene) is the simplest alkene.

 Alkynes are hydrocarbons which contain a triple
  bond between carbons.
 Alkynes end in “yne”.
 Ethyne, Propyne, Butyne, etc.

 Diagram the following hydrocarbons:

a) Propene       b) Butyne

c) 2 hexene      d) 2 - octyne
   Diagram the following hydrocarbons :

a) Butane                   b) 2-methyl propane

•   The molecular formula for both of these is C4H10
•   Even though the formula is the same the properties of these
    compounds is very different.
•   This is an example of isomers. Isomers are compounds with the
    same formula but different chemical and physical properties.
    (Boiling point, etc…)

 Diagram a pentane molecule, and two isomers of
  this molecule. Name each isomer.
           Aromatic Hydrocarbons

 Hydrocarbons can also
  form ring structures.
 The simplest would be
  cyclopropane, cyclobutane,
  and cyclopentane.
 When six carbons form a
  ring we enter a new class
  of hydrocarbons called
 Benzene is the first
  member of aromatic
  occurs when two or more equally valid
   structures can be drawn for a molecule
  benzene exhibits resonance
• explains unique properties of benzene
  and other aromatics
  – benzene is perfectly flat (electrons are
    delocalized, in other words, they are not
    fixed to one carbon but can move around)
  – bending or twisting of the aromatic
    molecule would disrupt the electron
    sharing and the stability of the molecule
        Properties of Benzene

 Molecular formula of benzene, C6H6, is based on its
  percent composition and molar mass
 MPbenzene = 5.5°C, BPbenzene=80.1°C
 Non-polar molecule
 Very unreactive with halogens
 Does not undergo addition reactions.
 All carbon-to-carbon bonds in benzene are the same
  length (determined by x-ray diffraction)
 Empirical evidence shows that all carbons are
  identical and that each carbon is bonded to one
           Naming Aromatics

1. Number the carbons around the ring to give
   branches the lowest number possible.
2. Name the branches and end with the parent
3. If benzene is a branch, use the prefix
                   Some examples

     CH3          CH2CH3


                                   CH3 CH2 CH2 CH CH CH3

methylbenzene   ethylbenzene
             Hydrocarbon Summary

 At this point we’ve concluded our study of hydrocarbons.
  Below is a summary of the hydrocarbon compounds we’ve

   Alkanes
   Alkenes
   Alkynes
   Branched alkanes, alkenes, alkynes
   Cyclic hydrocarbons
   Aromatic hydrocarbons
            Organic Compounds

 Hydrocarbons are used to synthesize a large amount
  of different organic compounds.
 In addition some of these organic compounds are
  naturally produced in living things.
 By adding substances and breaking bonds the
  hydrocarbon can become a new “class” of organic
               Organic Compounds

 The organic compounds we will study include:
      Alcohols              * sugars
      Aldehydes             * starches
      Amine’s               * lipids
      Carboxylic Acids (Organic Acids)
      Esters                * proteins
      Ethers
      Ketones
Distillation of
Crude Oil
(physical processes)

Boiling points are
used to separate the

The smaller the
hydrocarbon the
further it travels up
the tower.

Larger molecules
can go to the
cracking process.
Chemical Processes
Catalytic cracker. The
feedstock of long-chain
hydrocarbons (1) is mixed with
hot catalyst (2) and vaporized.
The vapor/powder mixture is
carried to the reactor where the
cracking reactions occur.
Cyclones (3) extract the
cracked hydrocarbon vapor
and pass it to the fractionating
column where it is
fractionated, yielding
petroleum gases and gasoline
(4), light gas oil (5), medium
gas oil (6), and heavy gas oil
(7). Spent catalyst meanwhile
is mixed with steam (8) and
carried in a current of hot air
(9) to the catalyst regenerator
where it is cleaned and
recycled (10. Waste gases are
drawn off (11) and vented.
       Other processing in Refining

 Solvent Extraction
     A physical process
     A solvent is used to
      selectively dissolve
      and separate
      desirable products
      or to remove
              Catalytic Reforming and
 Catalytic Reforming            Alkylation (isomerization)
     A chemical process              A chemical process
     Changes straight chain          Changes straight chain
      alkanes in to benzene            alkanes into branched
      or aromatic                      alkanes
      hydrocarbons.                   Branched alkanes can
     The aromatics can                also burn better than
      burn better.                     straight chain alkanes.
  Hydrocracking uses H2 to break longer chains into smaller
          Removing Sulfur from
1. Gasoline is vaporized at 500 oC
2. Hydrogen Gas is injected and reacts with
   sulfur to form hydrogen sulfide gas
3. The mixture is cooled and the H2S(g) is
4. The H2S(g) is converted to liquid sulfur for
   use in fertilizers and asphalt.

Organic compounds can undergo:
•Complete Combustion
      •   CxHy + O2          CO2 + H2O(g)
         This is exothermic producing heat and light
•Incomplete Combustion
  •       CxHy + O2            C or CO or CO2 + H2O(g)
         This occurs when amounts of oxygen are
          low, they can still be balanced as usual.

 Alcohols can be produced 3 different ways.
  Alcohols are compounds with an OH functional
  group (Hydroxyl) on a carbon skeleton.

     C- C–
                     Hydroxyl Group
              Alcohol Properties

 Alcohols with up to 4 carbon atoms are soluble in
  water as a result of the OH group on the carbon
 As more carbon atoms are added to the chain the
  solubility decreases.
 Alcohols have higher boiling points than do the
  hydrocarbons from which they are formed from.
             Types of Alcohols

 There are three types of alcohols: Primary,
  Secondary, and tertiary. These types of alcohols
  are determined by “where” the OH is on the carbon
 Primary : OH is at the end of a carbon chain.
 Secondary: OH is in the middle, with 2 C atoms
  attached to the C with the OH.
 Tertiary : OH is in the middle with 3 C atoms
  attached to the C with the OH.
                  Alcohol Types

 Diagram a primary alcohol below : ( ethanol)

• Diagram a secondary alcohol below: (2 – butanol)

* Diagram a tertiary alcohol below: 2-methyl-2-propanol
                 Naming Alcohols

 Alcohols are named by finding their hydrocarbon skeleton
  and ending this with “ol”.
 The OH group is identified to which carbon in the chain it is
  attached to.

Name the following alcohol and identify it as primary,
  secondary, or tertiary.
 Alcohols can have more than one OH group on a
  hydrocarbon chain.
 Alcohols with two OH’s are called diols, and the
  prefix di is added before the “ol” in naming.
 Alcohols with three OH’s are called triols, and the
  prefix “tri” is added before the “ol” in naming.
Write the structural formula for 1,2-ethanediol. This is
  also known as ethylene glycol or antifreeze.
          Naming and Classifying
1) Draw the structural formula for the following
   alcohols and classify them:

a) 3-hexanol              b) methanol

c) 1,2,3-propanetriol (glycerol)
              Alcohol Formation

 Alcohols can be produced three ways :
1) From using bacteria or yeast in the process of
   fermentation. (ethanol and carbon dioxide are the
   waste products of yeast as they eat sugar) 12%

2) Addition of water to an alkene. (with an acid
3) Hydrolysis of a halocarbons.
              Alcohol Formation

• Diagram the formation of ethanol from ethene +
  water ( with an acid catalyst H2SO4)

* Diagram the formation of ethanol from the
  hydrolysis (splitting by water) of chloroethane.
    Helpful Websites for Alcohols


 Halocarbons are organic compounds in which
  halogens have replaced hydrogen.
 Halocarbons are named as to where the halogens are
  attached, and how many halogens there are.
 The halogen prefix is used : fluoro, chloro, bromo,
                       Halocarbon Uses

 Halocarbons are used
  extensively as pesticides,
  insecticides, dry cleaning,
  and other areas.
 Many of the most toxic
  chemicals have been
 PCB’s : poly chlorinated
  biphenols, are toxic
  synthesized halocarbons.
                                  DDT : a halocarbon which
DDT: 1,1,1-trichloro-2,2-bis(p-
chlorophenyl) ethane              was banned in 1972

 PCB’s are halocarbons
  which contain two phenols
  with chlorine on them.
 PCB’s have been shown to
  be accumulative in fatty
  tissue, and bioaccumulate.
 The biphenols typically can
  persist in soil for 15-25
            Naming Halocarbons

 Draw the structure for the following :

a) Trichloromethane (chloroform)

b) Tetraiodomethane:           c) 2-fluoro pentane

 Ethers are organic compounds which have an oxygen atom
  bonded to two different carbons.
 Ethers are named by naming the compound on each side and
  ending in “ether”. Or by writing the short version of each
  with “oxy” in the middle.
 Ethers were used anesthetics, but safer gases have been
 Small ethers are soluble in water, but larger ethers are
 Applications of ethers are solvents, gasoline additive, etc.
                   Naming Ethers

•   Draw the structural diagram for the following :

a) Dimethyl ether        b) methoxypentane

c) Diethyl ether         d) Diphenyl ether

 Aldehydes are organic compounds which have a
  carbonyl group(C=O) at the end of a carbon chain.
 Aldehydes are named by ending the molecule with
  an “al”.

Diagram ethanal, and propanal below:
             Uses of Aldehydes

 Aldehydes are used as preservatives, flavorings,
  perfumes, etc.
 Vanilla flavoring and cinnamon are natural aldehyde
 Ethanol is converted to acetaldehyde (propanal) in
  the human body.

 Ketones are a class of organic compounds with a
  carbonyl group (C=O) in the middle of a carbon
  chain. (Ketones are never alone)
 Propanone is the simplest ketone and is known as
  acetone. Acetone is a top 50 industrial chemical.
 Acetone is a common solvent for nonpolar
  substances. (fingernail polish remover)
 To name ketones end the carbon chain in “one”.
        Organic Acids (Carboxylic
 Carboxylic acids are a group of organic compounds
  which have a (COOH) functional group.
 Carboxylic or organic acids are weak acids.
 Examples are : acetic acid, citric acid, benzoic acid,
 To name these acids use the carbon chain root : and
  add the suffix “oic” and the word acid.
          Naming Organic Acids

 Draw the structure for the following organic acids:

a) Methanoic acid              b) Ethanoic acid

c) Butanoic acid               d) Propanoic acid
        Properties of Organic Acids

 Methanoic acid (formic acid) is the acid in bee and ant
 Ethanoic acid is acetic acid, found in vinegar
 Small chain organic acids are soluble in water.
 Lactic acid is an organic acid which builds up in body cells.
 Ascorbic acid (Vitamin C) is found in citrus fruits and
 Bacteria reacts butter into butanoic acid. (rancid butter)

 Esters are organic compounds formed when an alcohol is
  added to an organic acid.
 Esters have distinctive odors.
 Esters have the functional group : (COOC)
 Esters are named by naming the alcohol name first ending in
  “yl”, then the acid name is given ending in “oate”.
 When an ester is synthesized from an alcohol and organic
  acid, the alcohol gives off the (O) atom , and the acid gives
  two (H) atoms to form water.

 Diagram the reaction of ethanoic acid with
  methanol. Name the ester which forms.

 Draw the structural formula for the following

a) Ethyl butanoate       b) pentyl ethanoate

 An amine is an organic
  compound which
  contains an “amino”
  functional group.
 An amino functional
  group is NH2
 Amines can contain
  several amino
  functional groups.

 Amines are named by
  adding the suffix “amine”
  to the root name of the
 Amines are also named by
  naming the hydrocarbon
  ending in “yl” with the
  suffix “amine”.

 Amines are important
                               Amino Group
  biological compounds.
 Amino acids which make
  up proteins contain an
  amino group along with an
  organic acid group.
 Amines are found in DNA.
 Amines are the basis of
  several addictive drugs :
  nicotine, cocaine, and      Methamphetamine
                Naming Amines

 Draw the structure for the following amines.

a) Butanamine            b) pentylamine

 Amides are produced when
  amines are added to an
  organic acid.
 Amides have an amino
  group and a carbonyl group
  attached to an end carbon.
 Amides are by adding the
  suffix “amide” to the end
  of the hydrocarbon root.

 Amides are found in
  biological compounds
  and in some synthetic
  polymers such as

                          Nylon : a polymer with an amide
                          group in the chain.
               Naming Amides

 Draw the structure of

                          What is the name of the amide above?
     Organic Compound Summary

• The following are the organic compounds we’ve
  studied. They are identified by their “functional
• Hydrocarbons           * Esters
• Alcohols               * Organic Acids
• Ethers                 * Amines
• Ketones                * Amides
• Aldehydes              * Halocarbons

 Small organic molecules
  (monomers) can be reacted
  to form long organic
  molecules (polymers)
 Example of polymers are :
  polyethylene (plastic),
  polyvinylchloride (PVC),
  nylon, polyester, etc.
 Polymers can be formed by
  a condensation reaction
  (water is produced)

 Polymers can be
  formed by an
  elimination reaction,
  where a simple
  molecule (water, etc.)
  is removed and a new
  compound is formed.

    PVC : polyvinyl chloride

 Other polymers include
     Teflon
     Polystyrene
     Proteins
     Lipids
     Starches

                    Polytetrafluoroethene :teflon

 Nylon is a polymer
  involving an amide
 Nylon was synthesiszed in
  the 1930’s and named after
  the cities of New York and
 Nylon is produced by
  adding an organic acid to
  an amine.
 Nylon has many uses.

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