
Stereochemistry


a vs. b
trans- vs. cis-
http://www.elmhurst.edu/~chm/vchembook/209ci
strans.html
http://chemwiki.ucdavis.edu/Textbook_Maps/General_Chemistry_Textbook_Maps/Map%3A_Ball_et_al._%22The_Basics_o
f_GOB_Chemistry%22/13%3A_Unsaturated_and_Aromatic_Hydrocarbons/13.2_Cis-Trans_Isomers_(Geometric_Isomers)
http://chemwiki.ucdavis.edu/Textbook_Maps/General_Chemistry_Textbook_Maps/Map%3A_Ball_et_al._%22The_Basics_
of_GOB_Chemistry%22/13%3A_Unsaturated_and_Aromatic_Hydrocarbons/13.2_Cis-Trans_Isomers_(Geometric_Isomers)
http://mcat-review.org/covalent-bond.php
Enantiomers
(S)-(+)-lactic acid (left) and (R)-(–)-lactic acid (right) are
nonsuperposable mirror images of each other
http://en.wikipedia.org/wiki/Enantiomer
http://openwetware.org/wiki/Image:Simple_Cycloalkanes.png
Diastereomers –no mirror image, nonsuperimposable
http://chemwiki.ucdavis.edu/Organic_Chemistry/Chirality/Diastereomers
S vs R
http://en.wikipedia.org/wiki/Absolute_configuration
weight increase
S vs R
weight increase
(S)-(+)-lactic acid (left) and (R)-(–)-lactic acid (right) are
nonsuperposable mirror images of each other
http://en.wikipedia.org/wiki/Enantiomer

From which are they derived?
•
•
•
Alkanes (both normal and branched) –
synthesized by bacteria, algae, and plants
Common cycloalkane in crude oil
• methyl cyclopentane
• methyl cyclohexane
• ethyl cyclohexane
• 1,1,3-trimethyl cyclohexane
• decaline (trans-, cis-)
Diterpanes: C20 –derived from abietic acid
(conifer resin)
http://www.scielo.br/scielo.php?pid=S0103-50532
003000600017&script=sci_arttext
•
Steranes- from sterol
• C27 – cholestane
• C28 – ergostane, campostane
• C29 – Sitostane
http://aapgbull.geoscienceworld.org/content/95/7/
1257.figures-only
Petroleum generation in the southeast Texas
basin: Implications for hydrocarbon occurre
nce at the South Liberty salt dome
Tat Banga, Regina M. Capuano and Kadry
K. Bissada, AAPG Bull., 95, 1257-1291
C30-32 steranes may be from bacteria (and higher life forms, but minor)
•
•
Terpenes
• Diterpenes – C20
• Triterpenes – C30
• hopanoid (C27-C30) -bacteria
• extended hopane – bacteria, land plant
Alkenes – found only rare in petroleum because
the double bond is easily reduced. Plants and
microorganisms produce varieties of olefin
C30
b-Carotene
•
Aromatic hydrocarbons –contain at least one
benzene ring
• benzene, toluene, meta xylene, 1,2,4trymethylbenzene are major petroleum
aromatic constituents
• Alkyl benzene
toluene
http://en.wikipedia.org/wiki/Xylene
•
Polynuclear aromatics
• Naphthalene, anthracene, phenanthrene
toluene
http://en.wikipedia.org/wiki/Xylene
•
Porphirines: “tetraphyrrols” derived from
chlorophyll and found in sedimentary
organic matter and petroleum
Center atom can
be Mg, Fe, V, or
Ni.
Ni is most stable
Figure 1. The structures of tetraphenylporphyrin (A) and chlorophyll (B). Ph: Phenyl. Mg:
Magnesium. R: Side chain
http://spie.org/x38084.xml
•
Compounds derived from porphirines:
• pyrrol, pyridine
http://commons.wikimedia.org/wiki/
•
Compounds derived from lignin
- decomposition of lignin
forms phenols
http://www.chem.ucla.edu/harding/IGOC/M/methoxy_group.html
•
Lignin
http://5e.plantphys.net/image.php?id=130
Web Figure 13.4.A Partial structure of a hypothetical lignin molecule from European beech (Fagus s
ylvatica). The phenylpropanoid units that make up lignin are not linked in a simple, repeating way. T
he lignin of beech contains units derived from coniferyl alcohol, sinapyl alcohol, and para-coumaryl
alcohol in the approximate ratio 100:70:7 and is typical of angiosperm lignin. Gymnosperm lignin co
ntains relatively fewer sinapyl alcohol units. (After Nimz 1974.)
•
Decomposition of lignin forms phenols, a
small quantities of phenols have been found
in petroleum, but they are more common in
sediment and rock extracts
http://chemistry.tutorvista.com/organic-chemistry/phenolic-compounds.html
cresol
Propofol
anisol
adrenaline
xylenol