zumdahl’s chap. 22 organic chemistry chapter contents introduction alkanes c n h 2n+2 –isomers...
TRANSCRIPT
![Page 1: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/1.jpg)
Zumdahl’s Chap. 22
Organic Chemistry
![Page 2: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/2.jpg)
Chapter Contents Introduction Alkanes CnH2n+2
– Isomers– Nomenclature
– Cycloalkanes CnH2n
Alkenes CnH2n
Alkynes CnH2n–2
Aromatics Functional Groups
– Alcohols– Aldehydes– Ketones– Carboxylic Acids– Esters– Amines
![Page 3: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/3.jpg)
Organic Chemistry Once upon a time …
– It was believed that organic chemicals could only arise in life processes …
– That they were a product of life’s vitality. In 1828, German chemist Friedrich
Wöhler dispelled that myth when– (Mineral) ammonium cyanate, NH4CNO,
heated gave (organic) urea, (NH2)CO(NH2). As if we needed another source.
![Page 4: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/4.jpg)
Modern Views With the exception of petroleum
products, geological and elemental carbon is inorganic carbon.
Other carbon-containing molecules are organic by virtue of carbon’s presence.
There are no end to the combinatorial possibilities since C bonds to C!
![Page 5: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/5.jpg)
Carbon’s Flexibility sp, sp2, sp3 mean a rich geometry of
180°, 120°, and 109.43° angles in virtually endless chains and branches of organic molecules.
The most potent psychotropicchemical cocktail on Earth …CHOCOLATE!
![Page 6: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/6.jpg)
Carbon’s Reactivity
NOT. With the exception of unsaturated sites
(multiple carbon-carbon bonds), it is at the heteroatoms (non-CH atoms, X) in an organic molecule where lies the reactive site.
Common CX combinations are called functional groups and dictate reactivity.
![Page 7: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/7.jpg)
Inorganic Carbon Elemental carbon
– Graphite– Diamond
– Buckminsterfullerene Carbon oxides and halides Carbonates and carbides Simple cyano- compounds like HCN.
![Page 8: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/8.jpg)
ALKANES Saturated hydrocarbons, CnH2n+2.
– “Saturated” because they can’t take any more hydrogen atoms!
– Straight chains are H3C–(CH2)n–2–CH3
– Gaseous for n<5; solid for n>17 @ STP.– Inert (but for strong oxidizers)– Pathologically nonpolar.– Waxes, oils, & fuel gases as n decreases.
![Page 9: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/9.jpg)
Old Possum’s Naming After n=4, the prefixanes have Greek
numbers as their prefixes.– 5=pent, 6=hex, 7=hept, 8=oct, 9=non,
and 10=dec, 20=eicos, 30=triacos But n4 are named historically
– CH4, Methane (“intoxicate” from the Greek)
– Ethane, Propane, and Butane for 2,3,4.
![Page 10: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/10.jpg)
Branching & Isomers After n=3, it’s possible to let some C’s
bond with more than 2 other carbons.– But fewer than 5, of course!
– The # of structural isomers possible thereby grows exponentially with n.
– These isomers have similar chemical and physical properties.
– So they’re a bit expensive to separate, and one sees bottles labeled merely “hexanes.”
![Page 11: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/11.jpg)
Isomer Naming Older conventions would have that as
“isooctane,” but a good IUPAC name results from the following:– Name the longest C chain (pentane)– List the side groups in alphabetical order
with Greek prefixes (trimethylpentane)– Supply (smallest possible) positional indices
(2,2,4 trimethylpentane)– The gasoline power rating standard molecule.
![Page 12: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/12.jpg)
Cycloalkanes, CnH2n
If the two end C’s lose 1 H each, they have free valence to close a ring; voila, cyclo(whatever)ane.– Again properties similar to straight chains.– Can now have conformational isomers!– E.g., BOAT cyclohexane versus CHAIR
See the C3
and S6 here?
![Page 13: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/13.jpg)
Alkenes, CnH2n
Cycle formation isn’t the only possible result of dehydrogenation.
Adjacent C’s can double bond, C=C, making an (unsaturated) alkene.– Much more reactive (vulnerable e– pair)– Rigid orbitals rigid planar partners!– E.g., trans-5-methyl-2-hexene
Obligatory plane seen edge on
![Page 14: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/14.jpg)
Alkene Isomers While an sp3 CX2Y2 has only 1 isomer,
(every X and Y is adjacent to all the others)
the sp2 alkene C2X2Y2 has cis & trans isomers (where X is or isn’t on the same side of = as X).
– For longer hydrocarbons, cis & trans refer to the side the chain extends:
and trans for the opposite
cis-2-butene trans-2-butene
cis for the same side
![Page 15: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/15.jpg)
Alkynes, CnH2n–2
sp triple bonding makes a rigid 180° segment in a hydrocarbon.
It too is vulnerable to attack across the multiple bond site.– Double & triple bonds can suffer addition
where an AB molecule single bonds A and B to an unsaturated site. H2, HX, and X2 (where X is halogen) are favorites.
propyne
![Page 16: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/16.jpg)
Unsaturated Cycles Earlier we noted the stability lent to
benzene, C6H6, by MOs. Alternating single/double cycles occur
in many organic molecules similarly.– This class is called “aromatic” (by virtue
of their aroma).– The structure is often preserved in their
chemical reactions; they don’t add, they substitute instead.
bromobenzeneanthracene (edge on)
![Page 17: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/17.jpg)
Functional Groups Organic backbones can bear hetero-
atoms as reactive sites. Alkyl root symbolized as R, a generic
hydrocarbon radical (methyl, ethyl, etc.)
Functional groups append R, e.g.,R–OH, an alcohol, or R–CHO, aldehyde.
R–CO2H, a carboxylic acid, R–NH2, amine.
isobutraldehyde ormethylpropanal
![Page 18: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/18.jpg)
Alcohols, R–OH The –OH makes alcohol polar enough
to hydrogen bond. water soluble Fermentation product but vulnerable to
oxidation to aldehyde and acid.
glucose, C6H12O6
yeast
ethanol
2
CO2
+ 2
![Page 19: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/19.jpg)
Aldehydes, R–CHO Next C oxidation state up from alcohol.
– Degradation product in your liver! If C=O isn’t a chain end substituent,
it’s not an aldehyde but a ketone. Aldehydes are often flavorings, but Ketones are industrial solvents.
OC H
benzaldehyde,“bitter almond”
quinone
![Page 20: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/20.jpg)
Carboxylic Acids R–CO2H
Usual highest C ox. state in organics. End product of body’s alcohol degradation.
Weakly acidic but important buffers. React with alcohols to make highly
flavorful esters … a condensation rxn.
OC O–H
+ +
butanoic acid“rancid yak butter”
ethanol ethyl butyrate“pineapple”
water
![Page 21: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/21.jpg)
Amines, Rn–NH3–n
Come in three varieties, n = 1, 2, & 3.– “Primary” amines, n=1, are at chain end.– “Secondary” amine N bonds to 2 carbons.– “Tertiary” amines bond to 3 C.
– Weak base Kb diminishes as n increases.
Alcohols are also primary, secondary, and tertiary. (Primary are on end carbons.)
– But this refers to the bonding of the C to which OH is attached.
Coniine (2ndary) “hemlock”2-propyl-piperidine
![Page 22: Zumdahl’s Chap. 22 Organic Chemistry Chapter Contents Introduction Alkanes C n H 2n+2 –Isomers –Nomenclature –Cycloalkanes C n H 2n Alkenes C n](https://reader036.vdocument.in/reader036/viewer/2022062320/56649cea5503460f949b4d15/html5/thumbnails/22.jpg)
Mixed Functionality So H2NCH2CH2OH is an alcohol and
an amine; it becomes ethanolamine. But the monster C9H14N4O3 would be
agony to call by its IUPAC name.– So it’s known by it common name,
carnosine.How many Ka and Kb are expected?
1 and 4, respectively.