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Ch 25 Hydrocarbon compounds 25.1  Hydrocarbons
Organic Chemistry and Hydrocarbons <ul><li>Organic originally meant chemicals that came from  organisms </li></ul><ul><li>...
Friedrich Wohler 1800 – 1882 Used inorganic substances to synthesize urea, a carbon compound found in urine. This re-defin...
Organic Chemistry and Hydrocarbons <ul><li>Over a million organic compounds, with a dazzling array of properties </li></ul...
Organic Chemistry and Hydrocarbons <ul><li>Hydrocarbons contain only two elements: 1) hydrogen, & 2) carbon </li></ul><ul>...
Organic Chemistry and Hydrocarbons <ul><li>Review  structural formulas  - p.746 </li></ul><ul><li>Carbon has 4 valence ele...
Straight-Chain Alkanes <ul><li>Straight-chain alkanes contain any number of carbon atoms,  one after the other , in a  cha...
Straight-Chain Alkanes <ul><li>Combined with the -ane ending is a  prefix  for the number of carbons </li></ul><ul><ul><li...
Straight-Chain Alkanes <ul><li>Many alkanes used for  fuels : methane, propane, butane, octane </li></ul><ul><li>As the nu...
Naming Straight-Chain Alkanes <ul><li>Names recommended by IUPAC - the International Union of Pure and Applied Chemistry <...
Naming Straight-Chain Alkanes <ul><li>IUPAC names may be long and cumbersome </li></ul><ul><li>Common names may be easier ...
Branched-Chain Alkanes <ul><li>Branched-chain  means that other elements  besides hydrogen  may be attached to the carbon ...
Branched-Chain Alkanes <ul><li>A hydrocarbon substituent is called an  alkyl group  or sometimes  radicals </li></ul><ul><...
Branched-Chain Alkanes <ul><li>Rules for naming   - page 748 </li></ul><ul><li>1. Longest C-C chain is parent </li></ul><u...
- Page 699
Branched-Chain Alkanes <ul><li>From the name,  draw  the structure, in a right-to-left manner: </li></ul><ul><li>1. Find t...
- Page 700
Properties of Alkanes <ul><li>Draw 3-ethylpentane </li></ul><ul><li>Draw 2,3,4-trimethylhexane </li></ul><ul><li>Since the...
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Ch 25 sec1

  1. 1. Ch 25 Hydrocarbon compounds 25.1 Hydrocarbons
  2. 2. Organic Chemistry and Hydrocarbons <ul><li>Organic originally meant chemicals that came from organisms </li></ul><ul><li>1828 German chemist Friedrich Wohler synthesized urea in a lab </li></ul><ul><li>Today, organic chemistry is the chemistry of virtually all compounds containing the element carbon </li></ul>
  3. 3. Friedrich Wohler 1800 – 1882 Used inorganic substances to synthesize urea, a carbon compound found in urine. This re-defined organic chemistry.
  4. 4. Organic Chemistry and Hydrocarbons <ul><li>Over a million organic compounds, with a dazzling array of properties </li></ul><ul><li>Why so many? Carbon’s unique bonding ability! </li></ul><ul><li>Let’s start with the simplest of the organic compounds: Hydrocarbons </li></ul>
  5. 5. Organic Chemistry and Hydrocarbons <ul><li>Hydrocarbons contain only two elements: 1) hydrogen, & 2) carbon </li></ul><ul><ul><li>simplest hydrocarbons called “alkanes”, which contain only carbon to carbon single covalent bonds (C n H 2n+2 ) </li></ul></ul><ul><ul><li>methane (CH 4 ) with one carbon is the simplest alkane. It is the major component of natural gas </li></ul></ul>
  6. 6. Organic Chemistry and Hydrocarbons <ul><li>Review structural formulas - p.746 </li></ul><ul><li>Carbon has 4 valence electrons, thus forms 4 covalent bonds </li></ul><ul><ul><li>not only with other elements, but also forms bonds WITH ITSELF (nonpolar) </li></ul></ul><ul><li>Ethane (C 2 H 6 ) is the simplest alkane with a carbon to carbon bond </li></ul>
  7. 7. Straight-Chain Alkanes <ul><li>Straight-chain alkanes contain any number of carbon atoms, one after the other , in a chain -meaning one linked to the next (not always straight) </li></ul><ul><ul><li>C-C-C C-C-C-C etc. </li></ul></ul><ul><li>Names of alkanes always will always end with -ane </li></ul>
  8. 8. Straight-Chain Alkanes <ul><li>Combined with the -ane ending is a prefix for the number of carbons </li></ul><ul><ul><li>Table 22.1, page 745 (memorize the prefixes) </li></ul></ul><ul><li>Homologous series - a group of compounds that have a constant increment of change </li></ul><ul><li>In alkanes, it is: -CH 2 - (methylene) </li></ul>
  9. 9. Straight-Chain Alkanes <ul><li>Many alkanes used for fuels : methane, propane, butane, octane </li></ul><ul><li>As the number of carbons increases, so does the boiling and melting pt. </li></ul><ul><ul><li>The first 4 are gases; #5-15 are liquids; higher alkanes are solids </li></ul></ul><ul><li>Condensed structural formulas? Note examples on page 746 </li></ul>
  10. 10. Naming Straight-Chain Alkanes <ul><li>Names recommended by IUPAC - the International Union of Pure and Applied Chemistry </li></ul><ul><ul><li>end with –ane; the root part of the name indicates the # of carbons </li></ul></ul><ul><li>We sometimes still rely on common names, some of which are well-known </li></ul>
  11. 11. Naming Straight-Chain Alkanes <ul><li>IUPAC names may be long and cumbersome </li></ul><ul><li>Common names may be easier or more familiar, but usually do not describe the chemical structure! </li></ul><ul><ul><li>Methane is natural gas or swamp gas </li></ul></ul>
  12. 12. Branched-Chain Alkanes <ul><li>Branched-chain means that other elements besides hydrogen may be attached to the carbon </li></ul><ul><ul><li>halogens, oxygen, nitrogen, sulfur, and even other carbons </li></ul></ul><ul><ul><li>any atom that takes the place of a hydrogen on a parent hydrocarbon is called a substituent , or the branched part </li></ul></ul>
  13. 13. Branched-Chain Alkanes <ul><li>A hydrocarbon substituent is called an alkyl group or sometimes radicals </li></ul><ul><ul><li>use the same prefixes to indicate the number of carbons, but -ane ending is now -yl such as: methyl, ethyl, propyl, etc. </li></ul></ul><ul><li>Gives much more variety to the organic compounds </li></ul>
  14. 14. Branched-Chain Alkanes <ul><li>Rules for naming - page 748 </li></ul><ul><li>1. Longest C-C chain is parent </li></ul><ul><li>2. Number so branches have lowest # </li></ul><ul><li>3. Give position number to branch </li></ul><ul><li>4. Prefix (di, tri) more than one branch </li></ul><ul><li>5. Alphabetize branches (not prefix) </li></ul><ul><li>6. Use proper punctuation ( - and , ) </li></ul>
  15. 15. - Page 699
  16. 16. Branched-Chain Alkanes <ul><li>From the name, draw the structure, in a right-to-left manner: </li></ul><ul><li>1. Find the parent, with the -ane </li></ul><ul><li>2. Number carbons on parent </li></ul><ul><li>3. Identify substituent groups (give lowest number); attach </li></ul><ul><li>4. Add remaining hydrogens </li></ul>
  17. 17. - Page 700
  18. 18. Properties of Alkanes <ul><li>Draw 3-ethylpentane </li></ul><ul><li>Draw 2,3,4-trimethylhexane </li></ul><ul><li>Since the electrons are shared equally, the molecule is nonpolar </li></ul><ul><ul><li>thus, not attracted to water </li></ul></ul><ul><ul><li>oil (a hydrocarbon) not soluble in H 2 O </li></ul></ul><ul><ul><li>“ like dissolves like” </li></ul></ul>

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