chemistryatkanehs.weebly.com · Web viewAn alcohol such as 2-butanol can be written in a...
Transcript of chemistryatkanehs.weebly.com · Web viewAn alcohol such as 2-butanol can be written in a...
Chapter 22 – Alcohols, Ethers, Phenols, and Thiols Name____________________
• The various classes of compounds are identified by the presence of certain characteristic groups called functional groups. Through the chemical reactions of functional groups, it is possible to create or synthesize new substances.
Compare and contrast:
water alcohol ether phenol thiol
ALCOHOLSClassification of alcohols
• Alcohols are classified as primary (1°), secondary (2°), or tertiary (3°) depending on whether the carbon atom to which the –OH group is attached is directly bonded to one, two, or three other carbon atoms respectively.
Ex:
1
Polyhydroxy alcohols (aka __________________ )
Structural Representations of Alcohols
An alcohol such as 2-butanol can be written in a single-line formula by enclosing the –OH group in parentheses and placing it after the carbon to which it is bonded.
Applications to biochemistry:
Blood sugar (glucose) contains five alcohol groups. Using the structure of glucose shown here, label each group as 1°, 2°, or 3°.
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Naming alcohols
1. Select the longest continuous chain of carbon atoms containing the –OH group.
2. Number the carbon atoms in this chain so that the one bearing the -OH group has the lowest possible number.
Name each:
CH3CH2CH2CH2OH
Physical Properties of Alcohols
• The physical properties of alcohols are related to those of _______________________________________
• An alcohol molecule is made up of a ________________________________________________________.
Boiling Points of Alcohols
• Alcohols have _____________________________________________________________________
• The boiling points of the normal alcohols ________________________________________________
• Branched-chain alcohols have _________________________________________________________
Ex:
3
OH
CHH3C
CH3
CHH3CCH3 CH2CH2OH
OH OHHO
2-propanol(isopropyl alcohol)
3-methyl-1-butanol
cyclohexanol 1,3-cyclohexanediol
OH
CHH3C
CH3
CHH3CCH3 CH2CH2OH
OH OHHO
2-propanol(isopropyl alcohol) 3-methyl-1-butanol
cyclohexanol 1,3-cyclohexanediol
• Alcohols containing up to three carbon atoms are ____________________________________________
• The –OH group on the alcohol molecule is responsible for ____________________________________
___________________________________________________________________________________
Hydrogen Bonding in Alcohols
Hydrogen bonding definition:_________________________________________________________________
_________________________________________________________________________________________
Ex:
4
Glucose is one of the most important carbohydrates in biochemistry. Draw it and find its molar mass. How would you predict the water solubility of glucose to differ from that of 1-hexanol?
Chemical Properties of Alcohols
• Acidic and Basic Properties
• Oxidation
• Dehydration
• Esterification
Acidic properties:
• Alcohols can act as Brønsted-Lowry acids (proton donors).
• The resulting anion in the alcohol reaction is known as an alkoxide ion (RO-).
Basic properties:
• Alcohols can act as Brønsted-Lowry bases (proton acceptors)
• If an alcohol is mixed with a strong acid, it will accept a proton (act as a Brønsted-Lowry base) to form a protonated alcohol or oxonium ion.
Reactivity of alcohols with Na or K
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• The order of reactivity of alcohols with sodium or potassium is:
• Reactivity decreases with ______________________________________________________________ ___________________________________________________________________________________
Oxidation
• Oxidation is the ____________________________________________________________________
• Carbon atoms ______________________________________________________________________
Calculate the oxidation state of carbon in:
Methane methanol methanol methanoic acid carbon dioxide
The –OH group gives an organic compound the capability of forming an __________________, ______________________________, or ____________________________________
What is the product of oxidizing each?
1. 1-propanol
2. 2- propanol
3. 2-methyl-2-propanol
Common Oxidizing Agents:
Dehydration
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Alkanes Alcohols AldehydesKetones
CarboxylicAcids
Carbon dioxide
increasing oxidation state
• Alcohols can be dehydrated with sulfuric acid to form alkenes.
Intramolecular dehydration: (within the same molecule)
• For many alcohols, there is more than one way to remove water. Therefore the double bond can be located in different positions.
• The major product in such cases is the alkene in which ____________________________________
___________________________________________________________________________________
Saytzeff’s rule:
During intramolecular dehydration, if there is a choice of positions for the carbon-carbon double bond,
_________________________________________________________________________________________
_________________________________________________________________________________________
Intermolecular Dehydration: (between two different molecules)
• Primary alcohols can be dehydrated with sulfuric acid to form __________________
• A condensation reaction is when
Esterification (Conversion of Alcohols to Esters)
• An alcohol can react with a carboxylic acid to form _________________________________________
Ex of esterification:
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Utility of the Hydroxyl Functional Group
Three General Methods for Making Alcohols (ie; “lab preps of alcohols”)
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1. Hydrolysis of an ester.
2. Alkaline hydrolysis of an alkyl halide (1° and 2° alcohols only).
3. Catalytic reduction of aldehydes and ketones.
Hydrolysis of an ester
Hydrolysis is
Alkaline hydrolysis of an alkyl halide (1° and 2° alcohols only).
Catalytic Reduction of Aldehydes and Ketones
Common Alcohols
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Methanol
• Methanol is synthesized by ________________________________________________
• The most economical nonpetroleum source of carbon monoxide for making methanol is ____________
• Reaction:
Uses of methanol:
1. Conversion to ____________________________________
2. Manufacture of ______________________________________________
3. Denaturing ___________________________________________________
4. ____________________________________________________________
Ethanol
• Large quantities of ethanol are prepared by _______________________________
– ___________________________________________________________________
• Industrially, ethanol is made by ________________________________________________
– Reaction:
Uses of ethanol:
• An intermediate in the ______________________________________________________________
• A solvent for ______________________________________________________________________
• A compounding ingredient for ________________________________________________________
• An essential ingredient in ____________________________________________________________
2-Propanol (Isopropyl Alcohol)
2-Propanol is made from propene:
Uses of isopropyl alcohol:
1. To manufacture ________________________________________________________________
2. As an ________________________________________________________________________
3. As the principal ingredient ________________________________________________________
Ethylene Glycol (1,2-Ethanediol)
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Industrial synthesis:
Uses of ethylene glycol:
1. In the preparation of the _____________________________________________________________
2. As a major ingredient _______________________________________________________________
3. As a solvent in ____________________________________________________________________
4. In the formulations of _______________________________________________________________
Glycerol (aka ___________________________________________)
• Glycerol (also known as _____________) is an important ____________________________________
• It is obtained as a ____________________________________________________________________
• It is synthesized commercially from ______________________________.
Uses of glycerol: (each is directly related to ___________________________)
1. As a raw material in _____________________________________________________________
2. As an ________________________________________________________________________
3. As a _________________________________________________________________________
4. As a ______________________________________________.
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PHENOLS• The term phenol is used for the class of compounds that ________________
____________________________________________________
• The parent compound is also called phenol, C6H5OH.
Naming phenols: Many phenols are named as derivatives of the parent compound, via the general methods for naming aromatic compounds
Common phenols with special names:
Physical /chemical properties of phenols
• _________________________________________________
• _________________________________________________
• _________________________________________________
• Reaction:
Industrial production of phenol
• Phenol is obtained from _________________________________
• Several commercial methods ________________________________________________.
ETHERS
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OH OH
Br
OH
NH2
phenol m-bromophenol
p-aminophenol
OH OH
Br
OH
NH2
phenol m-bromophenol
p-aminophenolHO
OH OH
HO
OH
OHcatechol(o-dihydroxybenzene)
resorcinol(m-dihydroxybenzene)
hyrdroquinone(p-dihydroxybenzene)
HO
OH OH
HO
OH
OHcatechol(o-dihydroxybenzene)
resorcinol(m-dihydroxybenzene)
hyrdroquinone(p-dihydroxybenzene)
Ethers have the general formula:
Naming ethers
Individual ethers may be known by some common names:
dimethyl ether ethyl methyl ether
IUPAC naming rules for ethers:
1. Select the longest carbon continuous chain and label it with the name of the corresponding alkane.
2. Change the –yl ending of the other hydrocarbon group to –oxy to obtain the alkoxy group name.
e.g. CH3O- is called methoxy.
3. Combine the two names from Steps 1 and 2, giving the alkoxy name and its position on the longest carbon chain first, to form the ether name.
Examples:
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H3C O CH2CH3
CH3O- is the alkoxy group(methoxy)
This is the longest C-C chain, so call it ethane.
methoxyethane
H3CH2CH2C O CH2CH2CH2CH3
1-propoxybutane
H3CHC O CHCH2CHCH3
2-isopropoxy-4-methylpentane
CH3 CH3 CH3
H3CH2CH2C O CH2CH2CH2CH3
1-propoxybutane
H3CHC O CHCH2CHCH3
2-isopropoxy-4-methylpentane
CH3 CH3 CH3
Structure and properties of ethers:
• Ethers are somewhat more polar than ___________, but are much less polar than _____________.
• The more polar a compound, ___________ _________________________________
• Ethers – especially diethyl ether – are exceptionally good solvents for organic compounds.
Formation of peroxides from ethers
Oxygen of the air slowly reacts with ethers to form unstable peroxides that are subject to explosive decomposition
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Preparation of ethers: The Williamson Ether Synthesis
Reaction:
• The alkyl halide, RX, may be ____________________________, but NOT a _____________________
___________________________________________________________________
• The alkoxide, R’ONa, may be __________________________________________________________.
Ex:
THIOLS
Organic compounds that contain the -SH group are known as thiols or mercaptans
Properties of thiols:
1. ___________________________
2. Oxidation to __________________________
Reaction:
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CH2CH3
SH
H3CS
Hmethanethiol(methyl mercaptan)
H3C
2-propanethiol
CH2CH3
SH
H3CS
Hmethanethiol(methyl mercaptan)
H3C
2-propanethiol