2-2-11
Chapter 2
H3C
CH3
H
H OH
CH
H3C F
HO
CH
H3CF
O
CO
H3C
H
OH
O
CO
H3C
OH
H
+
+
XH
H2 / M
Cl
IC
H
H3C D
NC
CH
H3CD
(-):CN:
CH2
OH O
HCH3
CH3
H
Br Mg CH3
δ+ δ−
LiCu
2
saturated hydrocarbonsconstitutional isomers
IUPAC nomenclatureconformations
cis/trans isomers
nomenclature refinementfunctional groups
reactions, sources, properties
2-2-22
Chapter 2
H3C
CH3
H
H OH
CH
H3C F
HO
CH
H3CF
O
CO
H3C
H
OH
O
CO
H3C
OH
H
+
+
XH
H2 / M
Cl
IC
H
H3C D
NC
CH
H3CD
(-):CN:
CH2
OH O
HCH3
CH3
H
Br Mg CH3
δ+ δ−
LiCu
2
saturated hydrocarbonsconstitutional isomers
IUPAC nomenclature - continuedconformations
cis/trans isomers
nomenclature refinementfunctional groups
reactions, sources, properties
cp
42
2-2-33StructureStructure
HydrocarbonsHydrocarbons:: compounds only Cs and Hs
Saturated hydrocarbon:Saturated hydrocarbon: only single bonds
C
H CH
H
HH
C
C HH
H
HH
alkanealiphatic hydrocarbonacyclic saturated hydrocarbon
open or “linear” chain, saturated hydrocarboncp qz
2-2-44HydrocarbonsHydrocarbons
H-C-C-H
H
H
H
H
HydrocarbonsCs,Hs only
Alkanes
Only C-Csingle bonds
Class
C-Cbonding
ethane
Saturated Unsaturated
all C sp3
H-C C-HH
C CH
H H
triple bond(s)
structureslike:
Alkenes Alkynes Arenes
double bond(s)
sp2-sp2; π sp-sp; 2π n(sp2-sp2; π)
cp qz
2-2-55
CH4 methane (109.5o bond angles)
Structure of alkanes (aliphatic hydrocarbons, acyclic saturated hydrocarbon):
open or “linear” chain, saturated hydrocarbons
H
C
H
CH
H
HH
CH3CH3 ethane (109.5o)
propane ( 109.5o)
CnH2n+2 (alkanes)
CH3CH2CH3
H
HC
H
H
cp qz
2-2-66
2.2 methane, ethane, propane - 1 structure, but ….
C4H10 has 2 forms, same molecular formula but different arrangement - isomers
HC
CC
CH
H H
H
H
H
H
HH
HC
CC
H
HH
H
H H
C
HHH
bpt. -0.5oC -11.6oC
different connectivity - constitutional isomers
cp qz
2-2-77
CH3CH2CH2CH2CH3
C5H12
CH3CHCH2CH3
CH3
CH3-C-CH3
CH 3
CH3
Note example (problems) pg 59, 60
CH3 CH CH2
CH3
CH3
the same
cp qz
2-2-88Constitutional IsomerismConstitutional Isomerism
4,111,846,763
4,347
75
31
Constitutional Isomers
MolecularFormula
CH4
C5H12
C10H22
C15H32
C30H62
36,797,588C25H52
UNIQUE NAME for each?
IUPAC nomenclature system
cp qz
2-2-99IUPAC nomenclature: alkIUPAC nomenclature: alkananee
number of carbons (alk)+(ane) saturated HC
undec-dodec-
tetradec-pentadec-hexadec-heptadec-
nonadec-eicos-
tridec-
11121314151617
octadec- 181920
Prefixmeth-eth-prop-but-pent-hex-
oct-non-dec-
1234567hept-89
10
Carbons CarbonsPrefix
prefix+suffix
cp qz
2-2-1010Nomenclature - IUPACNomenclature - IUPAC
ParentParent:: longest (most important) carbon chain
substituent:substituent: group off parent chain
alkyl group:alkyl group: a substituent carbon gp
R- symbol
CH4 CH3-
CH3CH3 CH3CH2-ethane ethyl
alkane alkyl or R- group
methane methyl
cp qz
2-2-1111
CH3CHCH3
CH31
2 3
Nomenclature - IUPACNomenclature - IUPAC
1. name (prefix + suffix) longest HC chain
( parent or root name)
2. substituent(s) given name and number
propane2-methylpropane
3. 1 substituent, number chain to give it the lower number
CH3CH2CH2CHCH3
CH3
2-methylpentane
123
45 5
432
1
(not 4-methylpentane)
cp qz
2-2-1212Nomenclature - IUPACNomenclature - IUPAC
4. Identical Substituents: number from the end that gives the lower number
12
34
56
2,4-dimethylhexane
65
43
21not 3,5-dimethylhexane
Combine like substituents: di-, tri-, tetra-, etc.
Use commas to separate position numbers
cp qz
2-2-1313Nomenclature - INomenclature - IUPACUPAC5. Different substituents
- list them in alphabetical order- number -lower number to the 1st -substituent
[branch alkyl
group R group]
12
34
5 67
3-ethyl-5-methylheptane
76
54
3 21not: 3-methyl-5-ethylheptane
5-ethyl-3-methylheptane
cp qz
2-2-1414Nomenclature - IUPACNomenclature - IUPAC
6. di-, tri-, tetra-, etc. are not used in alphabetization
7. alphabetize substituents and then insert these prefixes
12 3
45
6
4-ethyl-2,2-dimethylhexane
(not 2,2-dimethyl-4-ethylhexane)
cp qz
2-2-1515
nonane
C
CC
C
CC
CC
CC
C
CHH H
C
HH
HH
H H
H
H
HHH
H
H
H
HH
HH
H
H
H
HH
HH
C
CC
C
CC
CC
CC
C
CHH H
C
HH
H H
H H
H
H
HHH
H
H
H
HH
HH
H
H
H
H H
HH
alkane
dimethyl
ethyl
-ethyl- , -dimethylnonane6-ethyl-3,3-dimethylnonane
cp qz
2-2-1616C & H ClassificationC & H Classification, not nomenclature, not nomenclature
Primary (1°C)Primary (1°C) C bonded to 1 other C and 3Hs (alkane or 2Hs func. gp)
[“methyl” group]C
CC
C
CC
CC
CC
C
CHH H
C
HH
H H
H H
H
H
HHH
H
H
H
HH
HH
H
H
H
H H
HH
Secondary (2°)Secondary (2°) C bonded to 2 Cs (2H)
[“methylene” gp.]
Tertiary (3°)Tertiary (3°) C bonded to 3 Cs (1H)
[“methine” ]
Quaternary (4°)Quaternary (4°) C bonded to 4 Cs
cp qz
2-2-1717Cycloalkanes CCycloalkanes CnnHH2n2n
Line-angle drawings
H2C
H2C CH2
CH
CH2
CH
CH3
CH3
C8H16
C
C CC
CC
C
C
cp qz
2-2-1818CycloCycloalkanesalkanes
nomenclature• open-chain name with cyclo- cyclo- prefix• name each substituent on the ring
1 substituent, no number
2 substituents, number by alphabetical priority
- list substituents in alphabetical order3+ substituents, number to give lowest set of numbers
- alphabetical order
cp qz
2-2-1919
CYCLOALKANES substituent + alk + ane
butyl + ethyl + cyclo + hept+ ane
alphabetical numbering priority
substituent + cyclo + alk + anecyclo +
1-butyl-4-ethylcycloheptane
cp qz
2-2-2020CycloalkanesCycloalkanesExample: (1) Incorrect name: 1,4-dimethyl-3-ethylcyclohexane
write the correct name.
hint - draw, rename
(c) (d)
c,d substituent(s) on substituents
(2) Write an IUPAC name for the following:
(a) (b)
cp qz
2-2-2121
dimethyl
Nomenclature
nonanecyclopropyl
6-cyclopropyl-2,4-dimethylnonane
CC
CC C
C
CH3C
CH3
H3C
H H
H H
H
H H
HCH3
H
H
H
return to more nomeclature details later
cp qz
2-2-2222Bicycloalkanes ---- outBicycloalkanes ---- out
Bicycloalkane:Bicycloalkane: an alkane that contains two rings that share two carbons
Spiroalkane two rings share one carbon
Bicyclo[4.4.0]decane(Decalin)
Bicyclo[2.2.1]heptane(Norbornane)
cp qz
2-2-2323
H3C
ConformationsConformations:: 3-D arrangements of atoms in a molecule from rotation/twisting about single bonds
Newman projectionNewman projection:: conformational view along a carbon-carbon bond
H3CH3C
H3CH3C
cp qz
2-2-2424ConformationsConformationsStaggered Staggered conformation:conformation: atoms/groups on 1 carbon are
as far apart as possible from the atoms/groups on adjacent carbon
H
H H
H H
H
= 60o
cp qz
2-2-2525ConformationsConformations
Eclipsed Eclipsed conformation:conformation: atoms/groups on 1-C in closet approach to atoms/groups on adjacent C
H
H H
H
HH
same plane= 0o
cp qz
2-2-2626ConformationsConformationsTorsional strain or eclipsed interaction strainTorsional strain or eclipsed interaction strain
strain (E) arises from nonbonded atoms rotate from staggered to eclipsed conformations
+12.6 kJ/mol
cp qz
2-2-2828ConformationsConformations
anti conformationanti conformation• a conformation about a single bond in which the groups
lie at a dihedral angle of 180°
CH3
H H
H H
CH3
cp qz
2-2-2929ConformationsConformations
Steric strainSteric strain (nonbonded interaction strain)(nonbonded interaction strain): when atoms separated by 4 (more) bonds are forced closer
Angle strain:Angle strain:when a bond angle must compressed or expanded from 109.5o
calculate total strain - determine the lowest energy conformation ( molecular mechanics )
cp qz
2-2-3131CyclopropaneCyclopropane
angle strain:angle strain: bond angles compressed (109.5° 60°)
torsional strain:torsional strain: all 6Hs eclipsed
strain energy highH
H
H
H
H
H
cp qz
2-2-3232CyclobutaneCyclobutane
puckering torsional strain
slight angle strain
H
H
H
H
H H
H H
H H
HH
H
H
HH
net - puckered (butterfly) minimum energy conformation
but strain energy highcp qz
2-2-3333CyclopentaneCyclopentane
“envelope” - torsional strain
slightly angle strain
envelope ~ 1/4th strain energy of cyclopropane
H
H
H
H
H H
H
H HH
H H
H
HH
H
H
H
H
H
cp qz
2-2-3434Cyclohexane - chair conformationCyclohexane - chair conformation
Bond bond angles - 110.9° StaggeredNo angle or torsional strainNo angle or torsional strain
six Hs are axial and six equatorial
H
H
H
H
H
H
HHH
H H H
cp qz
2-2-3535
cyclohexane 2 equivalent chair conformations
Flip converts
6 equatorial 6 axial
6 axial Hs in one chair 6 equatorial Hs in other
H
H
H
H
H
H
HHH
H H H
H
HH
H
H
H
H H
H H H
H?
cp qz
2-2-3636
Equatorial and axial methyl conformations
MethylcyclohexaneMethylcyclohexane
CH3
H
H
H
H
H
H
H
H H
H
H
H
H
H
H
H
H
H
HH
H
CH3
H +7.28 kJ/mol
94 / 6
cp qz
2-2-3737Cis,TransCis,Trans Isomerism Isomerism
Stereoisomers - Stereoisomers - compounds with: same molecular formula and connectivity
different orientation of atoms in space
cis,cis,transtrans isomersisomers - stereoisomers with:2 groups on same or opposite side of geometric
restriction (i.e. ring, double bond).
cp qz
2-2-3838CisCis,,TransTrans Isomerism Isomerism
trans-1,4-dimethylcyclohexane
cis-1,4-dimethylcyclohexane
CH3
H3C
H H
H3C
CH3H
H
cp qz
2-2-3939CisCis,,TransTrans IsomerismIsomerism
trans-1,4-dimethylcyclohexanediequatorial-methyl chair more stable by 14.56 kJ/mol
[2 x 7.28]
H
CH3
H
CH3
H
H
H H
H H H
HH
H
H
H
H
H
HHH3C
H H CH3
cp qz
2-2-4040ciscis,,transtrans isomerism isomerism
cis-1,4-dimethylcyclohexane
CH3
H
H
H
H
H
HHH
H H CH3 H
HH
CH3
H
H
H3C H
H H H
H
same energy
Note! flip reverses axial-equatorial but……. cis or trans doesn’t change
cp qz
2-2-4141CycloalkanesCycloalkanes
(2) Write an IUPAC name for the following:
(a) (b)
(c) (d)
c,d substituent(s) on substituents qz
2-2-4242Nomenclature - IUPACNomenclature - IUPAC
branched substituents
1-methylethyl (isopropyl)
propyl
CH3
-CH2CH2CH3
-CHCH3
1,1-dimethylethyl (tert-butyl)
1-methylpropyl (sec-butyl)
2-methylpropyl (isobutyl)
butyl
CH3
CH3
CH3
CH3
-CH2CH2CH2CH3
-CH2CHCH3
-CHCH2CH3
-C-CH3
Formula Formula
qz
2-2-4343
qz
1-tert-butyl-3-isobutylcyclopentane
Draw the structure of:
trans-1-tert-butyl-3-isobutylcyclopentane
H
H
H
H
OR
2-2-4444refinement of IUPAC Parentrefinement of IUPAC Parent
prefix-infix-suffixinfixinfix - nature of C-C bond(s)
suffixsuffix - class (functional group)
one (more) triple bond(s)
one (more) double bond(s)
single bonds
-yn-
-en--an-
Nature of C-C Bond(s)Infix
prefix-suffix
Chapter 4
qz
2-2-4545IUPAC - GeneralIUPAC - General
prop-enen-e = propene
eth-anan-ol = ethanol
but-anan-one = butanone
but-anan-al = butanal
pent-anan-oic acid = pentanoic acid
cyclohex-anan-e = cyclohexane
eth-ynyn-e = ethyne
eth-anan-amine = ethanamine
CH3CH=CH2
CH3CH2OH
CH3CH2CH2CH2COH
O
HC CH
CH3CH2CH2CH
O
CH3CCH2CH3
O
CH3CH2NH2
qz
2-2-4646Alkanes - what are they good for?Alkanes - what are they good for?
MAJOR - energy, to do work:
initiationCH4 2O2 CO2 2H2O+ +H0
-212 kcal/mol
H3C X2 H-X+ +H H3C X + heat + otherinitiation
some products
other - oils, lubricants
qz
2-2-4747Sources of AlkanesSources of Alkanes
Natural gas • 90-95% methane
Petroleum• gases (bp below 20°C)• naphthas, including gasoline (bp 20 - 200°C)• kerosene (bp 175 - 275°C)• fuel oil (bp 250 - 400°C)• lubricating oils (bp above 350°C)• asphalt (residue after distillation)
Coalqz
2-2-4848Physical PropertiesPhysical Properties
Intermolecular forces of attraction (example)strong: ion-ion (Na+ and Cl- in NaCl)
ion-dipole (Na+ and Cl- solvated in aqueous solution)medium:dipole-dipole and hydrogen bondingweak: dispersion forces (very weak electrostatic
attraction between temporary dipoles)
qz
2-2-4949
Branching (ball-like)less surface to interact: bpt, mpt, density
less
HC
CC
CH
H H
C
H
H H
H H
HC
CC
CC
H H
HH
H H
HH
HH
H
H
HH
δ+δ-
δ+
δ-
δ+δ-
Longer or Straight Chains - more interactions along chain.
HC
CC
H
H H H H
C CH
H H H
H
CHH
H
HC
CCH
HHHH
CC
H
HH
H
H
CHH
H
δ+
δ-
δ+δ+
δ-
Chapter 4
qz
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