Presentation on theme: "The basis for organic chemistry"— Presentation transcript:
1 The basis for organic chemistry HydrocarbonsThe basis for organic chemistry
2 Organic CompoundsContain C bonded to other elements, commonly H, O, N, S, and halogensCarbonCan form many different compounds due to its hybrid orbitalsHas intermediate electonegativity, so its most likely to form molecular compounds (Recall: molecular compounds have diverse properties)Can make single, double, and triple bondsCan form isomers (same molecular formula but different arrangement of atoms)
3 Types of HydrocarbonsSaturated: Contain the maximum number of hydrogens, single bonds between all carbonsUnsaturated: Contain 1+ double or triple bonds
4 Types of Hydrocarbons Aliphathic Carbons are arranged in chains Cyclic: Carbons are arranged in ringsAromatic: Contain a benzene ring
6 Naming Alkanes Based off the number of C atoms in the longest chain Count the number of C’s in the longest chainDetermine the appropriate rootAdd the suffix “ane”
7 Hydrocarbon Root Names # of CarbonsRoot Name1meth-2eth-3prop-4but-5pent-6hex-7hept-8oct-9non-10dec-
8 Structural ShorthandExplicit hydrogens (those required to complete carbon’s valence) are usually left off of drawings of hydrocarbonsC1C2C3C4C1C2C3C4Line intersections represent carbon atoms
9 Cyclic Alkanes Cyclopropane, C3H6 Cyclobutane, C4H8 Cyclopentane, C5H10Cyclohexane, C6H12Cycloheptane, C7H14Remember, explicit hydrogens are left out
10 Rules for Naming Alkanes (Nomenclature) For a branched hydrocarbon, the longest continuous chainof carbon atoms gives the root name for the hydrocarbon12344 carbon chain = butane
11 Naming Branched Alkanes Based off the number of C atoms in the longest chainCount the number of C’s in the longest chainDetermine the appropriate rootUse the numbered C’s to give the branches a position number add “yl” suffixAdd the suffix “ane”
12 Naming Branched Alkanes Important Rules:Start numbering from the end that will give you the lowest number of branchesIf there is more than one type of branch, name the branches in alphabetical orderIf there is more than two of the same type of branch, give the branch a position number and prefixes “di”, “tri” “tetra” etc.Put commas between numbers and hyphens between numbers and letters
13 Rules for Naming Alkanes (Nomenclature) When alkane groups appear as substituents, theyare named by dropping the -ane and adding -yl.—CH3 Methyl—CH2CH3 Ethyl—CH2CH2CH3 Propyl—CH2CH2CH2CH3 ButylMethyl
14 Rules for Naming Alkanes (Nomenclature) The positions of substituent groups are specifiedby numbering the longest chain of carbon atomssequentially, starting at the end closest to thebranching.1234Methyl
15 Rules for Naming Alkanes (Nomenclature) The location and name of each substituent arefollowed by the root alkane name. The substituentsare listed in alphabetical order (irrespective of anyprefix), and the prefixes di-, tri-, etc. are used toindicate multiple identical substituents.1234Name:2-methylbutaneMethyl
16 Nomenclature Practice Name this compound19 carbons = nonane24356789Step #1: For a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the hydrocarbon
17 Nomenclature Practice Name this compound9 carbons = nonane124356CH3 = methyl7chlorine = chloro89Step #2: When alkane groups appear as substituents, they are named by dropping the -ane and adding -yl.
18 Nomenclature Practice Name this compound9 carbons = nonane124356CH3 = methyl7chlorine = chloro8919NOT91Step #3: The positions of substituent groups are specified by numbering the longest chain of carbon atoms sequentially, starting at the end closest to the branching.
19 Nomenclature Practice Name this compound9 carbons = nonane124356CH3 = methyl7chlorine = chloro892-chloro-3,6-dimethylnonaneStep #4: The location and name of each substituent are followed by the root alkane name. The substituents are listed in alphabetical order (irrespective of any prefix), and the prefixes di-, tri-, etc. are used to indicate multiple identical substituents.
20 Naming Alkenes & Alkynes Count the number of C’s in the longest chain containing the double/triple bond.This is the parent chain, determine the rootNumber the parent chain so that the double/triple bond has the lowest possible position numberIdentify the position numbers of branchesSame rules as beforeWrite the branches in alphabetical orderWrite the root, including a prefix that identifies the position of the double/triple bondAdd the prefix “cyclo” if its cyclicAdd the suffix “ene” or “yne”
22 Naming Cyclic Hydrocarbons 1. Number the carbons in the ring, in either direction, so that the multiple bond is between the two lowest numbers, and the branches get the lowest possible position numbers.2. Identify branches.. Prefixes are the same di, tri, prop etc. and are written alphabetically.3. The root is –cyclo- plus the name for the number of carbon atoms in the ring.4. The suffix is –ane for cycloalkanes –ene for cycloalkenes and –yne for cycloalkynes.
26 Properties of Hydrocarbons Made up of mostly C and HRelatively nonpolarLow solubility in polar solvents (e.g. water)Good solvents for other nonpolar moleculesMostly london-dispersion forces (weak)Low boiling and melting points
27 Reactivity of Hydrocarbons Alkanes are generally less reactive than alkenes or alkynesAromatic compounds are more reactive than alkanes, but less reactive than alkenes and alkynes.Alkanes < aromatics < alkenes < alkynes
28 Reactions of Hydrocarbons Combustion:Hydrocarbons burn readily in air to produce carbon dioxide and water.Incomplete Combustion:Produces carbon and poisonous carbon monoxide.C3H8(g) O2(g) --> 3CO2(g) + H2O(g)C3H8(g) + 7/2 O2(g) --> C(s) + CO(g) CO2(g) H2O(g)
29 Reactions of AlkanesSingle bonds between carbon atoms are difficult to break. (This is why alkanes are relatively unreactive)Can undergo combustion reactions and substitution reactions
30 Reactions of Alkanes Substitution Reactions: Hydrogen atoms may be substituted by a halogen.The product is a halogenated alkane (alkyl halides)
31 Reactions of Alkenes and Alkynes Addition Reactions:Reactions in which a molecule is added to a double or triple bond.No loss of hydrogen atoms from the hydrocarbon
34 Markovnikov’s Rule “The rich get richer” When a hydrogen halide is added to an alkene or alkyne, the hydrogen atom bonds to the carbon atom that already has more hydrogen atoms.Carbon 1 has 2 H’sCarbon 2 has 1 H
35 Benzene Ring Does not act as 3 single bonds and 3 double bonds It’s 6 identical bonds of intermediate lengthDue to hybridization (delocalized, shared electrons)
36 Reactions of Aromatic Hydrocarbons Less reactive than alkenes and do not undergo addition reactions unless under conditions of extreme temperature or pressureDo undergo substitution reactions (more reactive than alkanes)