Organic Chemistry Ch. 18

Organic Chemistry Study of organic molecules: Study of organic molecules: – Hydrocarbons – Alcohols – Acids – Vitamins – Ethers Naming hydrocarbons Naming hydrocarbons Naming side groups Naming side groups Formation of polymers Formation of polymers

Alkane Saturated Hydrocarbons Saturated Hydrocarbons – Maximum # of H atoms; all single bonded carbon atoms Can exist as Chains or Rings Can exist as Chains or Rings Longest chain of carbons is called the Parent Chain Longest chain of carbons is called the Parent Chain Parent Chain tells you the base name Parent Chain tells you the base name ALWAYS end in ANE ALWAYS end in ANE Rings always include “Cyclo” Rings always include “Cyclo”

Properties of Alkanes Alkanes vary in Parent Chain length and complexity Alkanes vary in Parent Chain length and complexity Longer Parent Chains= higher melting/boiling points Longer Parent Chains= higher melting/boiling points 1-4 carbons  gases 1-4 carbons  gases 5-16 carbons  liquids 5-16 carbons  liquids +16 carbons  solids +16 carbons  solids Rings burn more uniformly while chains tend to explode Rings burn more uniformly while chains tend to explode Produce Structural Isomers Produce Structural Isomers – Same molecular formula but different structure and therefore different name

Writing Compounds Shorthand: Pentane Shorthand: Pentane CH 3 -CH 2 -CH 2 -CH 2 -CH 3 CH 3 -CH 2 -CH 2 -CH 2 -CH 3 Shows number of Carbon/Hydrogen but no structure Shows number of Carbon/Hydrogen but no structure Condensed: Condensed: CH 3 CH 2 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CH 2 CH 3 Structural Diagram: Structural Diagram:

Naming Alkanes Simple Alkanes you follow base name; Side groups make things more complicated Simple Alkanes you follow base name; Side groups make things more complicated Side group- any carbon chain, alcohol, ether, etc…attached to the parent chain Side group- any carbon chain, alcohol, ether, etc…attached to the parent chain Rules: Rules: 1)Parent chain is longest number of carbons 2)Side groups must have the LOWEST position numbers possible 3)Alkane side groups end in “-yl” 4)Multiple side groups use Latin numbers; di, tri, etc… 5)Multiple side groups are alphabetical pentane 2-methylbutane 2,2-dimethylpropane 4-ethyl-3-methylheptane

Practice Naming Alkanes CH 3 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 3 nonane 3-ethylhexane cyclopropylcyclopentane 5-(1-methylpropyl)decane (2,2-dimethylpropyl) cycloheptane

Alkenes Unsaturated Hydrocarbons; missing H atoms due to double bonds Unsaturated Hydrocarbons; missing H atoms due to double bonds Can exist as Chains or Rings Can exist as Chains or Rings Longest chain of carbons is called the Parent Chain (contains double bond) Longest chain of carbons is called the Parent Chain (contains double bond) Parent Chain tells you the base name Parent Chain tells you the base name ALWAYS end in ENE ALWAYS end in ENE Rings always include “Cyclo” Rings always include “Cyclo” ethene 3-octene cyclodecene

Naming Alkenes Rules: Rules: 1)Double bond must have the lowest position number possible 2)Use di, tri, ect… plus “ene” when there are multiple double bonds 3)If double bond is a side group add “-yl” to ene 4)Rules for side groups still apply 2-methyl-3-heptene Draw: 2,2,5-trimethyl-3-nonene 3,3-dimethyl-1-hexene

Properties of Alkenes Ethene gas is huge part of plastic production Ethene gas is huge part of plastic production Double bond produces Geometric Isomers Double bond produces Geometric Isomers – Double bond stops free rotation of atoms – Cis isomers  Same side – Trans isomers  Opposite side Trans Alkenes have higher melting points than Cis Alkenes Trans Alkenes have higher melting points than Cis Alkenes Alkenes become Alkanes through Hydrogenation Alkenes become Alkanes through Hydrogenation – Reacting with H 2 gas Cis Trans

Practice Naming Alkenes 2-ethlyhexene trans-2-pentene cis-3-(1-methylethyl)-2- hexene cyclopentene

Aromatic Hydrocarbons 6 carbon Alkene ring 6 carbon Alkene ring – Benzene Electrons shared equally in the ring; resistant to Hydrogenation Electrons shared equally in the ring; resistant to Hydrogenation Give of distinct aromas: Give of distinct aromas: – Cinnamaldehyde 肉桂醛 Cinnamon – Phenylethanol 苯乙醇 Roses Roses

Alkynes Unsaturated Hydrocarbons Unsaturated Hydrocarbons Contain triple bonded carbon atoms Contain triple bonded carbon atoms Naming rules are the same for Alkenes Naming rules are the same for Alkenes ALWAYS ends in YNE ALWAYS ends in YNE The longer the Alkyne the higher the boiling/melting points The longer the Alkyne the higher the boiling/melting points Made into Alkenes with Hydrogenation Made into Alkenes with Hydrogenation propyne 5-ethyl-3-heptyne 5-cyclopropyl-1-hexyne

Practice Naming Alkynes 5-methly-2-hexyne 4-methyl-1,5-octadiyne 5-ethyl-2-methyl-3-heptyne2-methyl-3-hexyne