有机化学英文课件chapter10 共74页PPT资料

10-6
Nomenclature of Alcohols
u Unsaturated alcohols
• show the double bond by changing the infix from -anto -en-
• show the the OH group by the suffix -ol • number the chain to give OH the lower number
hybridized carbon
M acintosh PICT
• bond angles about the hydroxyl oxygen atom are approximately 109.5°
im age form at is not supported
u Oxygen is sp3 hybridized
• ethanol forms intermolecular hydrogen bonds which increase attractive forces between its molecules resulting in a higher boiling point
• there is no comparable attractive force between molecules of dimethyl ether
10-14
Acidity of Alcohols
M acintosh P IC T im age form at
is not supported
10-15
Acidity of Alcohols
u Acidity depends primarily on the degree of stabilization and solvation of the alkoxide ion
u Dipole-dipole interaction: the attraction between the positive end of one dipole and the negative end of another
10-8
Physical Properties
u Hydrogen bonding: when the positive end of one dipole is an H bonded to F, O, or N (atoms of high electronegativity) and the other end is F, O, or N
Organic Chemistry
William H. Brown Christopher S. Foote Brent L. Iverson
10-1
Alcohols M a c in to s h P IC T and Thiols im a g e fo rm a t
is n o t su p p o rted
M a c in to s h P IC T im a g e fo rm a t
is n o t s u p p o rte d
• 1°alcohols with extensive -branching give large amounts of rearranged product
M a c in to s h P IC T im a g e fo rm a t
is n o t s u p p o rte d
• low-molecular-weight 1°and 2°alcohols are unreactive under these conditions
• 1°and 2°alcohols require concentrated HBr and HI to form alkyl bromides and iodides
is n o t s u p p o rte d
M a c in to s h P IC T im a g e fo rm a t
is n o t s u p p o r te d
10-5
Nomenclature of Alcohols
u Compounds containing more than one OH group are named diols, triols, etc.
• change the suffix -e to -ol
u Common names
• name the alkyl group bonded to oxygen followed by the word alcohol
10-4
Nomenclature-Alcohols
u Examples
M a c in to s h P IC T im a g e fo rm a t
M a c in to s h P IC T im a g e fo r m a t
is n o t s u p p o r te d
10-18
Reaction with HX
• with HBr and HI, 2°alcohols generally give some rearranged product
is n o t s u p p o r te d
u Alcohols are also converted to metal alkoxides by reaction with bases stronger than the alkoxide ion
• one such base is sodium hydride
10-12
Physical Properties
M acintosh P IC T im age form at
is not supported
10-13
Acidity of Alcohols
u In dilute aqueous solution, alcohols are weakly acidic M a c in to s h P IC T im a g e fo rm a t is n o t s u p p o rte d
M a c in to s h P IC T im a g e fo r m a t
is n o t s u p p o r te d
10-17
Reaction with HX
• 3°alcohols react very rapidly with HCl, HBr, and HI
M a c in to s h P IC T im a g e fo rm a t
M a c in to s h P IC T Chapter 10
im age form at
M acintosh PICT im age form at
is not supported
is not supported
10-2
Structure - Alcohols
u The functional group of an alcohol is an -OH group bonded to an sp3
10-9
Hydrogen Bonding
10-10
Physical Properties
u Ethanol and dimethyl ether are constitutional isomers.
u Their boiling points are dramatically different
is not supported
10-3
Nomenclature-Alcohols
u IUPAC names
• the parent chain is the longest chain that contains the OH group
• number the parent chain to give the OH group the lowest possible number
• as the bulk of the alkyl group increases, the ability of water to solvate the alkoxide decreases, the acidity of the alcohol decreases, and the basicity of the alkoxide ion increases
10-16
Reaction with Metals
u Alcohols react with Li, Na, K, and other active metals to liberate hydrogen gas and form metal alkoxides
M a c in to s h P IC T im a g e fo r m a t
• have higher boiling points • are more soluble in water
u The presence of additional -OH groups in a molecule further increases solubility in water and boiling point
CH2 CH2
OH OH
1,2-Ethanediol (Ethylene glycol)
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CH3 CHCH2 HO OH
1,2-Propanediol (Propylene glycol)
CH2 CHCH2
HO HO OH
1,2,3-Propanetriol (Glycerol, Glycerine)
• two sp3 hybrid orbitals form sigma bonds
to carbon and hydrogen
Macintosh PICT
• the remaining two sp3 hybrid orbitals each im age form at
contain an unshared pair of electrons
is n o t s u p p o rte d
10-19
Reaction with HX
u Based on
• the relative ease of reaction of alcohols with HX (3°> 2°> 1°) and
• the occurrence of rearrangements,
M acintosh P IC T im age form at
is not supported
10-7
Physical Properties
u Alcohols are polar compounds
Macintosh PICT image format is not supported
• they interact with themselves and with other polar compounds by dipole-dipole interactions
CH3 CH2 OH
Ethanol bp 78°C
CH3 OCH3
Dimethyl ether bp -24°C
10-11
Physical Properties
u In relation to alkanes of comparable size and molecular weight, alcohols
u Chemists propose that reaction of 2°and 3° alcohols with HX
• the negatively charged oxygens of methanol and ethanol are about as accessible as hydroxide ion for solvation; these alcohol are about as acidic as water
• the strength of hydrogen bonding in water is approximately 21 kJ (5 kcal)/mol
• hydrogen bonds are considerably weaker than covalent bonds
• nonetheless, they can have a significant effect on physical properties