copyright © houghton mifflin company. all rights reserved.3–13–1 12 hydrocarbon derivatives i...
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Copyright © Houghton Mifflin Company. All rights reserved. 3–1
12 Hydrocarbon Derivatives I
Compounds with carbon-heteroatom single bonds
Alkyl halides
Alcohols
Phenols
Ethers
Thiols
Amines
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12.2 Halogenated Hydrocarbons
Halogenated hydrocarbons have halogen atoms (–F, –Cl, –Br, –I) on a hydrocar-bon skeleton; R–X
1-bromobutane
H C C C C Br
H
HH
H
H
H
H
H
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12.2 Naming Halogenated Hydrocarbons
Halogens are treated as substituents, like alkyl substituents. The prefixes are fluoro–, chloro–, bromo–, iodo–.
C C
H
H
H Cl
Cl
Cl
1,1,1-trichloroethane
H3C C CH3
CH3
Br
2-bromo-2-methylpropane
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12.2 Properties of Halogenated Hydrocarbons
Many halogenated hydrocarbons are liquids with densities greater than 1.00 g/mL.
Halogenated hydrocarbons are not very polar, and are not soluble in water. They are good solvents for hydrocarbons, and are used to remove grease.
Halogenated hydrocarbons are not flammable, and are used in fire extinguishers (halons).
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Common Halogenated Hydrocarbons
Some halogenated hydrocarbons are used as inhalation anesthetics.
C
H
Cl Cl
Cl
trichloromethane,a.k.a chloroform
F C C H
F
F
Cl
Br
2-bromo-2-chloro-1,1,1-trifluoroethane,a.k.a halothane
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Common Halogenated Hydrocarbons
Some halogenated hydrocarbons are used as refrigerants. The chlorofluorocarbons destroy atmospheric ozone. All are green-house gases.
C
F
Cl F
Cl
C C
F
F
F H
H
F
1,1,1,2-tetrafluoroethane,a.k.a. R-134a
dichlorodifluoromethane,a.k.a. R-12
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Common Halogenated Hydrocarbons
Several halogenated hydrocarbons have been used as pesticides. Many have adverse environmental effects.
C
ClCl
H CCl Cl
Cl 4,4'-(2,2,2-trichloroethane-1,1-diyl)bis(chlorobenzene)
a.k.a. DDT, dichlorodiphenyltrichloroethane
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12.3 Alcohols
Alcohols have a hydroxy(l) group (–OH) on an alkyl chain; R–OH
Ethanol, Ethyl alcohol
HOCC
H
HH
H
H HOC
CC
C
C C
HH
H
H H
C
C C
C
CC
O C
H
H
H H
HH
H
H
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12.3 Naming Alcohols
Suffix is “-ol”
1. Find longest chain that bears –OH
2. Number carbons on chain so carbon bearing –OH has lowest possible number
3. Locate –OH by number of carbon
4. Locate and name any other substituents
5. Final “e” on name of hydrocarbon is dropped.
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12.3 Naming Alcohols
H C C C C OH
H
HH
H
H
H
H
H
Name these:
H3C C CH3
CH3
OH
Draw structures for:
2-methyl-1-propanol 2-butanol
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12.3 Naming Alcohols
Name this!
C
OH
CH2 CH2 CH3CH2
CH2
CH2 CH2 CH2 CH3
CH3
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12.4 Properties of Alcohols
Properties are driven by hydrogen bonding and polarity.
Alcohols up with up to 6 carbons are at least somewhat soluble in water.
Alcohols have higher melting and boiling points than alkanes of
similar molar mass.
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12.4 Properties of AlcoholsHydrogen bonding among alcohol molecules
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12.4 Properties of Alcohols
As alkyl chain on alcohol gets larger, properties become more alkane-like
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12.4 Properties of AlcoholsMelting and Boiling Points of Alkanes and Alcohols
-200
-100
0
100
200
300
400
0 5 10 15 20Number of Carbons
Temperature, °C
Alkane MP, °CAlkane BP, °CAlcohol MP, °CAlcohol BP, °C
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12.4 Properties of Alcohols
Classification of alcohols
Primary (1)
Secondary (2)
Tertiary (3)
R CH2 O H
CH O HR1
R2
C O H
R1
R2
R3
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12.4 Reactions of Alcohols
Alcohols can dehydrate (lose H2O) to produce alkenes.
Tertiary alcohols don’t react.
C C C
H3C
H3C
H
H
OH
H
H
H
H2SO4
180o CC
H3C
H3CC
C
H
HH
H + CC C
H
H
C
C
HH H
H H
HH H
+ H2O
Major Minor
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12.4 Reactions of Alcohols
Alcohols can dehydrate to produce ethers
This is most useful with primary alcohols; the alkene may also form.
H3C CH2 O H + H O CH2 CH3
H2SO4
140o C
H3C CH2 O CH2 CH3 + H2O
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12.4 Reactions of Alcohols
Alcohols oxidize to form C=O bonds.
The reaction is formally loss of H2.
Oxidizing agents:
KMnO4, K2Cr2O7
C
H
O H
R1
R2[O]
C O
R1
R2
H2O+
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12.4 Reactions of Alcohols
Different classes of alcohol react differently.
Primary alcohols:
AldehydeCarboxylic
acid
It can be hard to stop at aldehyde stage.
CR O
H
H
H[O]
CR H
O[O]
CR O
O
H
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12.4 Reactions of Alcohols
To make aldehyde, use CrO3 in pyridine. Keep water out of the reaction!
C
H
R
H
C
H
H
O H[O]
RC
H
O
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12.4 Reactions of Alcohols
Different classes of alcohol react differently.
Secondary alcohols:
Ketone
C O H
R1
R2
H
[O]C
O
R1R2
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12.4 Reactions of Alcohols
Different classes of alcohol react differently.
Tertiary alcohols:
Can’t react, no H on C!
C O H
R1
R2
R3
[O] No RXN
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Common Alcohols
Methanol CH3–OH Wood alcohol; used as solvent, reactant
Ethanol CH3–CH2–OH Grain alcohol; used as solvent, reactant, beverage!
2-Propanol CH3–CH(OH)–CH3
Isopropanol Rubbing alcohol; usedfor sterilization of in-jection sites
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Common Alcohols
Ethanediol HO–CH2–CH2–OH
Ethylene glycol Antifreeze; poisonous
Cholesterol Important biomolecule
OH
CH3
H H
CH3
CH3
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12.3 a Phenols
Alcohols have a hydroxy group on an aromatic ring; –OH
Phenol, a.k.a carbolic acid
HOCC
H
HH
H
H HOC
CC
C
C C
HH
H
H H
C
C C
C
CC
O C
H
H
H H
HH
H
H
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12.3 a Naming Phenols
Suffix is “phenol”
1. Carbon bearing hydroxyl is #1
2. Number carbons on ring so carbon bearing substituent has lowest possible number
OH
H3C CH3
Cl
OH
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12.3 a Naming Phenols
Phenols with several hydroxyls have cool names
Catechol Resorcinol Hydroquinone
Pyrogallol Phloroglucinol 1,2,4 Benzenetriol
OH
OH
OH
OHOH
HO
OH
OH
OH
OH
OHHO HO
OH
OH
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12.4 a Properties of Phenols
Properties are driven by hydrogen bonding, polarity, and aromaticity
Most phenols are solids
Phenols are weak acids
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12.4 a Reactions of Phenols
Phenols are weak acids and undergo acid- base reactions.
Phenoxide Hydronium
anion cation
OH
O +H
OH
H
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12.4 a Reactions of Phenols
Dihydroxyphenols oxidize to form quinones.
Hydroquinone Benzoquinone
Hydroquinones are antioxidants; they react with oxidizing agents and protect other com-pounds from oxidation.
OHHO[O]
O O H2O+
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12.4 a Reactions of Phenols
Dihydroxyphenols oxidize to form quinones.
Vitamin C (ascorbic acid) acts like hydroquinone.
O
OHHO
OR [O]O
O O
OR+ H2O
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Common Phenols
OH
Phenol, a.k.a.Carbolic acid
Disinfectant,Local anesthetic
C
O
OH
OH
Salicylic acidAnalgesic, basisfor aspirin andBen-Gay
OHButylatedhydroxy-toluene, a.k.a. BHT
Preservative,antioxidant
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Common Phenols
CH3H3C
HO OH
Bisphenol-A
HO
H H
CH3 OH
Estradiol
Used in epoxides andpolycarbonate plastics,has estrogenic properties
A major component ofestrogen
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12.5 Ethers
Ethers have oxygen atoms bonded to two carbon atoms.
CH3 CH2 O CH2 CH3
Diethyl ether
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12.5 Naming Ethers
Common names of ethers are formed by naming the hydrocarbon group on either side of the oxygen atom and adding the word “ether.” The hydrocarbons are named in alphabetical order.
CH3 CH2 O
Ethyl phenyl ether
CH3 O CH3
Dimethyl ether
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12.5 Naming Ethers
Cyclic ethers have interesting names; these turn up in carbohydrates.
C C
CO
CC C
CO
C C
CC
C
CO
H
H H
HH
H
HHH
H
H
H H H
HHH H
Furan Tetrahydro-furan (THF)
Pyran
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12.5 Naming Ethers
Ethylene oxide and propylene oxide, cyclic ethers with three-membered rings, are important oddities. Such ethers are called epoxides.
O O CH3
ethylene oxide propylene oxide
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12.5 Naming Ethers
Cyclic di- and tri-ethers:
OO
O
O
O O
O OO
Dioxolane Dioxane Trioxane Dioxepane
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12.5 Properties of Ethers
Ethers have boiling points similar to those of hydrocarbons with similar structures.
Like hydrocarbons, they are flammable.
CH3 CH2 O CH2 CH3 CH3 CH2 CH2 CH2 CH3
Boiling point 35°C Boiling point 36°C
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12.5 Properties of EthersEthers have water solubilities similar to those
of isomeric alcohols. They are hydrogen bond acceptors.
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12.5 Reactions of EthersEthers are not particularly reactive. They are
good solvents for certain reactions.
Ethers form explosive hydroperoxides in the presence of oxygen. Ethers are treated with antioxidants to prevent this.
C C
CO
CH
H
HHH
H
H
H
+ O2 C C
CO
CH
O
HHH
H
H
HO H
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12.5 Reactions of Ethers
Polymeric ethers are made from ring-opening reactions of epoxides, which are much more reactive than most ethers.
HO [CH2 CH2 O]n H HO [CH2 CH O]n H
CH3
Poly(ethylene glycol) (PEG)Carbowax
Poly(propylene glycol) (PPG)
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Common Ethers
Diethyl ether and chloroform were used as anesthetics in the 1840’s. Fluorinated ethers are not flammable and have fewer side effects than either of these.
CC
OC
F FF
FCl
F
F
H
Enflurane
CC
OC
F ClF
FF
F
F
H
Isoflurane
CC
OC
F HF
FF
F
F
H
Desflurane
CC
OC
C HF
FF
H
F
HFF F
Sevoflurane
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Common Ethers
Diethyl ether and tetrahydrofuran (THF) are very useful solvents. Unlike most ethers, THF is freely soluble in water.
CH3 CH2 O CH2 CH3
Diethyl ether
C C
CO
CH
H
HHH
H
H
H
Tetrahydrofuran (THF)
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Common Ethers
Bisphenol-A diglycidyl ether (BADGE) is the “resin’ in most epoxy glues.
CH3H3C
O OOO
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12.6 Thiols
Thiols are the sulfur analogs of alcohols. The SH is called a sulfhydryl group.
Another name for thiols is mercaptans, from “mercury capture.” Thiols and sulfide ions react with heavy metals.
R OH
R SH
Alcohol Thiol
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12.6 NamingThiols
Thiols are named like alcohols. The suffix for the sulfhydryl group is “-thiol.” The -e at the end of the alkane name is retained.
CH3 CH2 CH
OH
CH3 CH3 CH2 CH
OH
CH3
2-butanol 2-butanethiol
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12.6 Properties of Thiols
Thiols are polar, but are not capable of hydrogen bonding.
Boiling points of thiols are lower than those of analogous alcohols.
Small thiols are often have strong odors.
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12.6 Properties of Thiols
1-butanethiol is added to nat-ural gas as an odorant, so leaks can be detected.
Skunk odor is due to thiols.
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12.6 Reactions of Thiols
Thiols are weak acids and undergo acid-base reactions.
ethanethiol thiolate anion
+ OH1– + H2OCH3 CH2 S H CH3 CH2 S
CH3 CH2 S + H2O CH3 CH2 S + H3OH
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12.6 Reactions of Thiols
Thiols undergo oxidative coupling to form disulfides.
This reaction is important in protein chemistry.
R S H + H S R[O]
R S S R + H2O
thiols disulfide
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12.6 Reactions of Thiols
Oxidative coupling is reversible. Reducing agents, [H2], restore the thiols.
These reactions are involved in “permanents” and straightening agents for hair.
R S S R
disulfide
[H2]R S H + H S R
thiols
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12.7 Amines
Amines contain nitrogen. They are organic derivatives of ammonia.
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12.7 Naming AminesCommon names of amines are formed by
naming the alkyl groups attached to the nitrogen in alphabetical order and adding the suffix “amine.”
CH3 CH2 NH2
ethylamine
CH3 CH2 N
H
CH2 CH3
diethylamine
NCH3
CH2 CH3ethylmethylphenylamine
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12.7 Naming AminesAromatic amines are called anilines.
The prefix “N-” locates alkyl groups on nitrogen.
NH H
NH CH2 CH3 N
H3C CH3
aniline N-ethylaniline N,N-dimethyl-aniline
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12.7 Naming AminesCyclic aromatic amines with nitrogen in the
ring are common in biological molecules.
N
N
N
N
N
N N
N
pyridine pyrimidine pyrazine triazine
N
N
N
H H
pyrrole imidazole
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12.7 Naming Amines
Fused aromatic rings that contain nitrogen are also common.
N
N
N
N
N
H
quinoline purine
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12.7 Naming Amines
Aliphatic rings that contain nitrogen are also common.
N
N
N
O
N N
H H
H
H H
piperidine piperazine morpholine pyrrolidine
O OHHO
N CH3
morphine
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12.8 Structures of Amines
Aliphatic amines have tetrahedral electronic geometry and trigonal pyramidal molecular geometry at the nitrogen atom.
R1N
R2
R3
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12.8 Structures of Amines
Aromatic amines have trigonal planar electron-ic geometry and trigonal planar or angular molecular geometry at the nitrogen atom.
The lone pair on pyrrole’s nitrogen is part of the aromatic electron system.
NN
H
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12.8 Properties of Amines
Amines are polar molecules. 1 and 2 amines are hydrogen-bond donors. 3 amines are hydrogen-bond acceptors.
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12.8 Properties of AminesNitrogen is less electronegative than oxygen,
so amines are less polar than alcohols. Melting points and boiling points are lower than those of alcohols of similar structure.
H3C NH2
Name Formula BP, °C
Methylamine -6.3
Methanol H3C OH
Ethylamine
Ethanol
H3C CH2 NH2
65
17
H3C CH2 OH 78
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12.8 Properties of Amines
Aromatic amines follow the same trends.
Amines with 6 or fewer carbon atoms are at least somewhat water-soluble.
Name Formula BP, °C
Aniline C6H5 NH2
MP, °C
C6H5 OHPhenol
-6
41
184
182
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12.8 Properties of Amines
Odors are prominent and unpleasant.
Small amines smell like ammonia.
Slightly larger amines smell like dead fish.
H2N CH2 CH2 CH2 CH2 NH2
H2N CH2 CH2 CH2 CH2 CH2 NH2
putrescine
cadaverine
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12.8 Reactions of Amines
Amines are weak bases and undergo acid-base reactions.
ammonium ion
R1 N
R2
R3 + H2O R1 N
R2
R3
H
+ OH1−
R1 N
R2
R3 + H3O1+ R1 N
R2
R3
H
+ H2O
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12.8 Reactions of Amines
Amines undergo alkylation when reacted with alkyl halides.
Even tertiary amines do this. The prod-ucts are called quaternary amine or ammonium salts or just “quats.”
R1 N
R2
R3 + R4Cl R1 N
R2
R3
R4
+ Cl1−
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Common AminesSimple alkyl amines, e.g. methylamine,
have already been mentioned.
Amines from plants are called “alkaloids” because they are basic. They often have physiological effects.
N
NH
CH3
Nicotine, a stimulantfrom tobacco
N
N N
N
CH3OH
O
CH3
H3C
Caffeine, a stimulantfrom coffee and tea