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4/18/2016 HYDROCARBONS S http://www.youtube.com/watch?v=mAjrnZ-znkY HYDROCARBON BONDING HYDROCARBONS S – A hydrocarbon is a compound consisting of only hydrogen and carbon. – The carbon to carbon can be single, double, or triple bonds. – The bonds are always nonpolar. – Alkanes are hydrocarbons with only single bonds. • Each successive compound differs from the one before it only by a CH2 – As the number of Carbons increase so does the MP/BP – As the number of Carbons increase so does structural isomers HYDROCARBON BONDING S S (A) straight (B) branched (C) in a closed ring single (A) double (B) triple (C) Each carbon atom has four dashes, which represent four bonding pairs of electrons, satisfying the octet rule. 1 S First Ten Hydrocarbons Name 2 ALKANES CnH2n+2 3 4 5 6 Methane Number of Molecular Carbon Atoms Formula CH4 1 CH4 S Condensed Structural Formula LEARN IT, LOVE IT! Ethane 2 C2H6 CH3CH3 Propane 3 C3H8 CH3CH2CH3 Butane 4 C4H10 CH3CH2CH2CH3 Pentane 5 C5H12 CH3CH2CH2CH2CH3 Hexane 6 C6H14 CH3CH2CH2CH2CH2CH3 Heptane 7 C7H16 CH3CH2CH2CH2CH2CH2CH3 Octane 8 C8H18 CH3CH2CH2CH2CH2CH2CH2CH3 Nonane 9 C9H20 CH3CH2CH2CH2CH2CH2CH2CH2CH3 Decane 10 C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 1 4/18/2016 H S #1 METHANE S S #2 ETHANE S H H H H H C H H H C C C C H H H H H Methane CH4 Butane C4H10 Methane is Tetrahedral H Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 634 #2 ETHANE H H C C H H H Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635 S #3 PROPANE S Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635 2 4/18/2016 #3 PROPANE H H H H C C C H H H S Structure of Propane S H Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635 #4 BUTANE S Structure of Butane S Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635 #5 PENTANE S S Hydrocarbons (alkanes) SINGLE BOND 3 4/18/2016 ALKANE PROPERTIES Name Number of Molecular Melting Boiling Carbon Atoms Formula Point, oC Point, oC S # of Isomers Methane 1 CH4 -182.5 -161.5 0 Ethane 2 C2H6 -183.2 -88.6 0 n-Propane 3 C3H8 -187.7 -42.1 0 n-Butane 4 C4H10 -138.3 -0.5 2 n-Pentane 5 C5H12 -129.7 36.1 3 n-Hexane 6 C6H14 -95.3 68.7 5 n-Heptane 7 C7H16 -90.6 98.4 9 n-Octane 8 C8H18 -56.8 125.7 18 n-Nonane 9 C9H20 -53.6 150.8 35 n-Decane 10 C10H22 -29.7 174.0 75 butane H H H H H NAMING ALKANES S 1. Find the longest continuous chain of carbon atoms in the molecule 2. Start numbering the chain at the carbon nearest the first branching point constituents have the lowest #s possible) 3. Name and number the constituents Hydrocarbon groups that are attached to the longest continuous chain and named using the parent name, changing the –ane suffix to –yl. 4. Write out the name of the molecule S Isomers of Pentane S C C C C H H H H H Isomers of Butane C4H10 H HH H C H H C C C H H H H methyl propane or isobutane Timberlake, Chemistry 7th Edition, page 383 STRUCTURAL ISOMERS Timberlake, Chemistry 7th Edition, page 385 S • Carbon can make 4 covalent bonds – There are more carbon-based compounds present on earth than the total of all compounds lacking carbon – Compounds that have the same molecular formula, but different structures (arrangements of the atoms) are called isomers. • Example: Isomers of C4H10 – Butane: CH3 CH2 CH2 CH3 – Isobutane: CH3 CH Structural Isomers All have formula C5H12 NAMING ALKANES S • Identify the longest continuous chain. • The locations or other groups of atoms attached to the longest chain are identified and numbered by counting from the end of the molecule which keeps the numbering system as low as possible. CH3 CH3 4 4/18/2016 METHYL GROUPS (R) S H H C H H H H C C C C H H H H H Methane CH4 H C ? Butane C4H10 H H ? R H H H H C H R H C C C C H H H H H Methyl -CH3 C C C 1 6 52 43 Butyl -C4H9 S H H CH3 H S H H H H S CH3 CH3 H H C H 3 4 C C C C C C H C H 25 2,4,5 trimethyl 3ethyl octane CH3 H C H 16 H 3, 3 dimethyl hexane or Lowest sum of numbers is correct 4, 4 dimethyl hexane 2, 5 dimethyl 3,3diethyl nonane ALKENES AND AKYNES S Hydrocarbons Number of Alkanes Carbon Atoms CnH2n + 2 Alkenes CnH2n Alkynes CnH2n-2 S 1 CH4 Methane 2 C2H6 Ethane C2H4 Ethene C2H2 Ethyne 3 C3H8 Propane C3H6 Propene C3H4 Propyne Butane C4H8 Butene C4H6 Butyne Pentene C5H8 Pentyne 4 C4H10 5 C5H12 Pentane C5H10 6 C6H14 Hexane C6H12 Hexene C6H10 Hexyne Heptane C7H14 Heptene C7H12 Heptyne Octene C8H14 Octyne 7 C7H16 8 C8H18 Octane C8H18 9 C9H20 Nonane C9H18 Nonene C9H16 Nonyne C10H20 Decene C10H18 Decyne 10 C10H22 Decane 5 4/18/2016 ALKENES AND ALKYNES S • Alkenes and Alkynes – Alkenes are hydrocarbons with at least one double carbon to carbon bond. • To show the presence of the double bond, the –ane suffix from the alkane name is changed to –ene. – The alkenes are unsaturated with respect to hydrogen • This means it does not have the maximum number of hydrogen atoms as it would if it were an alkane (a saturated hydrocarbon). ALKYNES ALKENES S CnH2n S S S S (CnH2n-2) 6 4/18/2016 S S S S S H H H H H C C C C H C C C C H 1 Butane C4H10 H 2 3 H H H H H • Ethylene is the gas that ripens fruit, and a ripe fruit emits the gas, which will act on unripe fruit. • A ripe tomato placed in a sealed bag with green tomatoes will help ripen them. S H H H H 4 H H but(1)ene 1-butene n-butene H H H H C C C C H H H H Butene Butane C4H8 1 2 3 4 2-butene 7 4/18/2016 DNA damage S DO YOU CARE S NAMING ALKENES/ ALKYNESS Guanine + HO OH 8-Hydroxyguanine S – Naming is similar to naming alkanes except: • The longest continuous chain must contain the double bond. • The base name now ends in –ene. • The carbons are numbered so as to keep the number for the double bond as low as possible. • The base name is given a number which identifies the location of the double bond. – An alkyne is a hydrocarbon with at least one carbon to carbon triple bond. – Naming an alkyne is similar to the alkenes, except the base name ends in –yne. The most highly mutagenic lesions identified FUNCTIONAL GROUPS S ALCOHOLS S – Alkenes can also add to each other in an addition reaction to form long chains of carbon compounds. • this is called polymerization – The atom or group of atoms that are added to the hydrocarbon are called functional groups. • Functional groups usually have multiple bonds or lone pairs of electrons that make them very reactive. FREE RADICALS????? 8 4/18/2016 Alcohols S – An alcohol has a hydrogen replaced by a hydroxyl (-OH) group. – The name of the hydrocarbon that was substituted determines the name of the alcohol. – The alcohol is named using the hydrocarbon name and adding the suffix –ol. • If methane is substituted with an OH group it becomes methanol • If a pentane group is substituted with an OH group it is pentanol. • For alcohols with more than two carbon atoms we need the number the chain so as to keep the alcohol group as low as possible. S Naming Functional Groups S S 9