Chapter 22_ Organic Chemistry and Hydrocarbons

					    Chapter 22: Organic Chemistry and Hydrocarbons
1. Hydrocarbons: Gasoline, diesel fuel, and kerosene are examples of liquid fuels. A
   solid fuel, coal, produced the steam for the locomotives that pulled old-time trains.
   These fuels are mixtures of compounds called hydrocarbons. Hydrocarbons are
   molecules composed of hydrogen and carbon.


2. How is the number of valence electrons in carbon atoms related to the bonds that
   carbon atoms form?
   Because carbon has four valence electrons, a carbon atom always forms four covalent
   bonds. One carbon atom can form a single covalent bond with four hydrogen atoms.
   The simplest organic compounds contain only carbon and hydrogen and are called
   hydrocarbons.


3. Alkanes: An alkane is a hydrocarbon in which there are only single covalent bonds.
   What are two possible arrangements of carbon atoms in an alkane?
        Ethane is the simplest of the straight-chain alkanes, which contain any
           number of carbon atoms, one after the other, in a chain.




           Hydrocarbons are used as fuels.




           In a condensed structural formula, some bonds and/or atoms are left out of the
            structural formula. Although the bonds and atoms do not appear, they are
            there.
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Branched-Chain Alkanes
  Notice in the molecule above that there are branches off of the longest chain of
  carbon atoms. The longest chain of carbon atoms is called the parent chain. Other
  carbons may be attached. A hydrocarbon attachment is called an alkyl group.




Name this branched chain hydrocarbon:




Ball-and-stick model show the arrangement of atoms in 4-ethyl-2,3-dimethylheptane.




                                                Answer: 3,3 dimethylhexane




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 4. Properties of Alkanes
    Molecules of hydrocarbons, such as alkanes, are nonpolar molecules. The nonpolar
    molecules in the oil spill are not attracted to the polar water molecules in the ocean.

 5. Unsaturated Hydrocarbons
    Roach traps are baited with pheromones, which roaches produce to attract mates. The
    structure of many pheromones is based on unsaturated hydrocarbons. You will study
    two types of unsaturated hydrocarbons—alkenes and alkynes.

 What are the structural characteristics of alkenes?
       Alkenes: At least one carbon-carbon bond in an alkene is a double covalent
       bond. Other bonds may be single carbon-carbon bonds and carbon-hydrogen
       bonds.
       • Organic compounds that contain the maximum number of hydrogen atoms per
        carbon atom are called saturated compounds.
       • Compounds that contain double or triple carbon-carbon bonds are called
        unsaturated compounds.




 What are the structural characteristics of alkynes?
  Alkynes: At least one carbon-carbon bond in an alkyne is a triple covalent bond. Other
  bonds may be single or double carbon-carbon bonds and single carbon-hydrogen
  bonds. Name this molecule:




6. What are Isomers?
    The retinal molecule in the rod and cone cells of your eye has a hydrocarbon skeleton.
    When light strikes a cell containing retinal, it causes a change in the three-
    dimensional structure of the retinal molecule. The structures before and after the light
    strikes are examples of isomers.

  How do the properties of structural isomers differ?
    Compounds that have the same molecular formula but different molecular structures
    are called isomers. Structural isomers are compounds that have the same molecular
    formula, but the atoms are joined together in a different order Structural isomers
    differ in physical properties such as boiling point and melting point. They also have
    different chemical reactivities.



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   Ex: Both butane and 2-methylpropane have the molecular formula C4H10. The atoms
   in their molecules are arranged in a different order, so they are structural isomers.




What are stereoisomers?
      Stereoisomers are molecules in which the atoms are joined in the same order,
      but the positions of the atoms in space are different.
      In the trans configuration, the methyl groups are on opposite sides of the
         double bond.
      In the cis configuration, the methyl groups are on the same side of the double
         bond.




           There is a trans and a cis configuration of 2-butene because a methyl group is
            attached to each carbon of the double bond.




7. Hydrocarbon Rings
Beta-carotene is an important nutrient in carrots that also gives carrots their orange color.
The hydrocarbon skeleton of beta-carotene contains hydrocarbon rings. You will learn
about hydrocarbon rings and the properties of compounds formed from these rings.

What is the general structure of cyclic hydrocarbons?
In some hydrocarbon compounds, the carbon chain is in the form of a ring. Compounds
that contain a hydrocarbon ring are called cyclic hydrocarbons.




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How are cyclic hydrocarbons named?
Add “cyclo-“ to the hydrocarbon name. The structures above are cyclopropane,
cyclobutane, cyclopentane, and cyclohexane.

Aromatic Hydrocarbons
What is the most accurate description of the bonding in a benzene ring?
        In a benzene molecule, the bonding electrons between carbon atoms are shared
        evenly around the ring. An aromatic compound is an organic compound that
        contains a benzene ring or other ring in which the bonding is like that of
        benzene.

The Structure of Benzene
  Benzene can be shown as switching, or resonating, between two arrangements of
  alternating double and single bonds.




   The three symbols below can be used to represent the benzene ring. If the bonds are
   shown as alternating single and double bonds (on right), it is important to remember
   that bonds don’t actually alternate and that all six bonds are identical.




Substituted Aromatic Compounds
  When benzene is an attachment, it is called a phenyl group.




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   Compounds with an attachment on a benzene ring are named as a derivative of
   benzene and are named accordingly. A benzene ring can have two or more
   attachments.




    The molecules of many dyes include benzene rings.

8. Functional Groups
    Organic compounds can be classified according to their functional groups. A
    functional group is a specific arrangement of atoms in an organic compound that is
    capable of characteristic chemical reactions.




Functional Groups
   The hydrocarbon skeletons in the components of these products are chemically
   similar. Functional groups give each product unique properties and uses.

What is a halocarbon?
         A halocarbon is a carbon-containing compound with a halogen (group 17
         element). Halocarbons are a class of organic compounds containing covalently
         bonded fluorine, chlorine, bromine, or iodine. To name them you use the prefix
         fluoro-, chloro-, bromo-, iodo-. The figure below shows the IUPAC names,
         structural formulas, and space-filling models for a halocarbon.



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   Ex: What is the correct IUPAC name for the compound CH2BrCH2CH2Br?
      a. methylbromoethylbromide
      b. dibromopropane
      c. 1,3-dibromopropane◄
      d. propyl-1,3-dibromide

What are Alcohols and Ethers?
     • An alcohol is an organic compound with an — OH group.
     • The —OH functional group in alcohols is called a hydroxyl group or alcohol
       group.
     • When using the IUPAC system to name alcohols, drop the -e ending of the parent
       alkane name and add the ending -ol.

    Ethanol (ethyl alcohol) is a common component of many household products.




                      2-propanol is also called isopropyl alcohol, or “rubbing alcohol.”

    Alcohols can have more than one hydroxyl group. Add di, tri to name right before
   the “-ol” These alcohols contain one, two, or three hydroxyl groups. Alcohols are
   used in many household products, including antiseptics, antifreeze, and cosmetics.




Properties of Alcohols
Fermentation is the production of ethanol from sugars by the action of yeast or bacteria.
A second reaction product, carbon dioxide, causes bread to rise.
        Ethanol is the intoxicating substance in alcoholic beverages.
        It is a depressant that can be fatal if taken in large doses at once.
        Denatured alcohol is ethanol with an added substance to make it toxic
           (poisonous). Denatured alcohol is used as a reactant or as a solvent in
           industrial processes.
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Ethers
A patient does not experience pain during surgery when given a general anesthetic. The
earliest anesthetics, used during the Civil War, belonged to a class of chemical
compounds called ethers. You will read about the chemical characteristics of ethers that
make them good anesthetics.

What is the general structure of an ether and how are the alkyl groups of an ether
named?

An ether is a compound in which oxygen is bonded to two carbon groups. The general
structure of an ether is R—O—R. The alkyl groups (R) attached to the ether are named
in alphabetical order and are followed by the word ether.




                                                          Ethyl Methyl Ether
 What is the general formula for a carboxylic acid?
     • A carboxyl group consists of a double bonded O and a hydroxyl group.    This is
       called a carboxyl group or -COOH
     • To name a carboxylic acid you write the name of the parent chain, drop the e, and
       add “-oic acid”    Ex: methanoic acid, ethanoic acid
     • The general formula for a carboxylic acid is RCOOH.
     • Carboxylic acids are weak because they only ionize slightly in solution
     • Carboxylic acids give a variety of foods—spoiled as well as fresh—a distinctive
       sour taste.



                     propanoic acid




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      • Many continuous-chain carboxylic acids were first isolated from fats and are
       called fatty acids.
      • Stearic acid, an 18-carbon acid obtained from beef fat, is used to make
       inexpensive wax candles.




                                             stearic acid

Stearic acid is a SATURATED fatty acid (saturated with hydrogen)

Linoleic acid is a POLYUNSATURED fatty acid




It is abundant in olive oil and safflower oil.

What is the general structure of an ester?
  Esters are derivatives of carboxylic acids in which the —OH of the carboxyl group
  has been replaced by an —OR from an alcohol.




    Ethyl ethanoate is a low-molar-mass ester.




    This ester is the banana odor.

    Esters impart the characteristic aromas and flavors of many flowers and fruits.
    Marigolds, raspberries, and bananas all contain esters.




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Carbonyl Compounds

Have you heard of benzaldehyde or vanillin? It is likely that you have eaten these organic
molecules, called aldehydes, in ice cream or cookies. You will read about the properties
that are associated with carbonyl compounds, such as aldehydes.
         Vanillin, an aldehyde, comes from vanilla beans.
         A solvent used to remove nail polish is acetone, a ketone.
         You will not be responsible for naming or drawing structural formulas of
            ketones or aldehydes…we’ll save that one for your college professor.

9. Polymerization
Snap beads are a favorite toy for toddlers. Chemical compounds called monomers and
polymers resemble snap beads. Monomers are joined end-to-end to form long chains
called polymers.
     • A polymer is a large molecule formed by the covalent bonding of repeating
       smaller molecules.
     • The smaller molecules that combine to form a polymer are called monomers.




                         Polyethylene is used to make many household items, including
plastic bottles, bags, and food containers


Polypropylene, a stiffer polymer than polyethylene, is used to make plastic utensils and
containers, and other items such as this whistle.




    Polypropylene is prepared by the polymerization of propene.


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Polystyrene foam is a poor heat conductor, useful for insulating homes and for molded
items such as coffee cups and picnic coolers.




Polyvinyl chloride (PVC) is used for pipes in plumbing. It is also produced in sheets,
sometimes with a fabric backing, for use as a tough plastic upholstery covering.
Polyvinyl chloride (PVC) is a halocarbon polymer. Vinyl chloride is the monomer of
polyvinyl chloride.




Polyisoprene, harvested from tropical plants such as a rubber tree, is the polymer that
constitutes rubber.




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