Chapter 10: Structure and Synthesis of Alcohols Flashcards
What are alcohols?
Organic compounds containing hydroxy (-OH) groups
Alcohols are versatile synthetic intermediates in organic chemistry.
What is the IUPAC suffix used for alcohols?
-ol
What are the two main components of peppermint oil?
- l-menthol
- l-menthone
What is the definition of primary alcohol?
An alcohol with the -OH group attached to a primary carbon atom
What is a secondary alcohol?
An alcohol with the -OH group attached to a secondary carbon atom
What is a tertiary alcohol?
An alcohol with the -OH group attached to a tertiary carbon atom
What are phenols?
Compounds with a hydroxy group bonded directly to an aromatic ring
What is the bond angle in methanol?
108.9°
What is the bond angle in water?
104.5°
How do you name an alcohol using IUPAC nomenclature?
- Name the longest carbon chain with the -OH group
- Drop the final -e and add -ol
- Number the chain to give the lowest number to the -OH group
What is the common name for methyl alcohol?
Methanol
What is the IUPAC name for 2-methylpropan-1-ol?
Isobutyl alcohol
What are diols?
Alcohols with two -OH groups
What is a glycol?
A 1,2-diol with two hydroxy groups on adjacent carbon atoms
How are glycols typically synthesized?
By the hydroxylation of alkenes
What is the IUPAC name for ethylene glycol?
Ethane-1,2-diol
What property do alcohols and phenols share?
Both contain a hydroxy (-OH) group
What is the structure of ethyl alcohol?
CH3-CH2-OH
True or False: The hydroxy group takes precedence over double and triple bonds in nomenclature.
True
What is the IUPAC name for butan-2-ol?
A secondary alcohol
What is the common name for 1-bromo-3,3-dimethylbutan-2-ol?
A complex alcohol that requires IUPAC nomenclature
What is the bond length of the C-O bond in methanol?
1.4 A
What are some common uses of isopropyl alcohol?
As a skin cleanser for injections and minor cuts
Fill in the blank: Alcohols can be converted to most other _______ groups.
functional
What is the order of precedence of functional groups in naming organic compounds?
- Carboxylic acids
- Esters
- Aldehydes
- Ketones
- Alcohols
- Amines
- Alkenes, alkynes
- Alkanes
What happens to the -OH functional group when it appears on a structure with a higher-priority functional group?
It is named as a hydroxy substituent
What is the IUPAC name for ethylene glycol?
ethane-1,2-diol
Ethylene glycol is commonly used as automotive antifreeze.
What is the common name for propane-1,2-diol?
propylene glycol
Propylene glycol is used in medicines and foods.
What does the term ‘ortho’ refer to in phenols?
1,2-disubstituted
The terms ortho, meta, and para are used to describe the positions of substituents on the benzene ring.
What is the common name for 2-bromophenol?
ortho-bromophenol
What is the IUPAC name for catechol?
benzene-1,2-diol
What is the application of concentrated phenol?
It is a potent neurotoxin and causes deep, painless burns.
Which alcohol is also known as methyl alcohol?
methanol
What is the boiling point of ethanol?
78 °C
Which intermolecular forces are primarily responsible for ethanol’s high boiling point?
Hydrogen bonding and dipole-dipole attractions
Fill in the blank: The alcohol with the formula CH3CH2OH is commonly known as _______.
ethyl alcohol
What is the density of propan-2-ol?
0.79 g/ml
True or False: Dimethyl ether can engage in hydrogen bonding.
False
Dimethyl ether lacks -O-H hydrogens necessary for hydrogen bonding.
What effect does the size of the alkyl group have on the solubility of alcohols in water?
Solubility decreases as the alkyl group becomes larger.
What is the common name for 2-methylphenol?
ortho-cresol
What is the solubility of methyl alcohol in water at 25 °C?
miscible
What happens to the water solubility of alcohols with larger alkyl groups?
It decreases.
What is the boiling point of glycerol?
290 °C
True or False: Methanol is less flammable than gasoline.
True
What is the IUPAC name for isopropyl alcohol?
propan-2-ol
What is the primary use of methanol in industry?
It is used as a common industrial solvent.
What is the density of ethanol?
0.79 g/ml
Fill in the blank: The molecular formula for ethane-1,2-diol is _______.
HOCH2CH2OH
What is the boiling point of butan-2-ol?
100 °C
What is the common name for phenylmethanol?
benzyl alcohol
Which alcohol is produced from the destructive distillation of wood chips?
methanol
What is the boiling point of propan-1-ol?
97 °C
What type of alcohol is commonly used in cosmetics and pharmaceuticals?
propylene glycol
What is methanol used for?
Methanol is a starting material for a variety of methyl ethers, methyl esters, and other compounds used in plastics, medicines, fuels, and solvents.
Why was methanol used in the Indianapolis 500 from 1965-2006?
Methanol was used because it is less flammable than gasoline and water is effective against methanol fires.
What are the advantages of using methanol as a fuel?
Advantages include high octane rating, low pollutant emissions, and lower flammability.
What is a disadvantage of using methanol as a fuel?
Methanol has lower energy content, requiring 1.7 g to produce the same energy as 1 g of gasoline.
How does methanol affect fuel-system components?
Methanol is hard on rings, seals, and plastic fuel-system parts due to its excellent solvent properties.
What historical significance does ethanol have?
Ethanol was likely discovered when rotten fruit was consumed, leading to the fermentation of fruit juices.
What is E85?
E85 is a fuel blend containing 85% ethanol and 15% gasoline.
What impact do government subsidies have on ethanol production?
Government subsidies have increased the price of food grains while having little impact on fuel supplies.
What is the typical alcohol concentration in the alcoholic solution resulting from fermentation?
The alcoholic solution typically contains only 12-15% alcohol.
What process is used to increase ethanol concentration for hard liquors?
Distillation is used to increase the ethanol concentration to about 40-50%.
What is a minimum-boiling azeotrope?
A minimum-boiling azeotrope is a mixture of liquids that boils at a lower temperature than either of its components.
How can absolute alcohol be obtained from 95% ethanol?
By passing the 95% azeotrope through a dehydrating agent such as anhydrous calcium oxide (CaO).
What is the primary method for synthesizing industrial ethanol since World War II?
The gas-phase reaction of water with ethylene using catalysts at high-temperature and high-pressure.
True or False: Methanol is less toxic than ethanol.
False.
What is denatured alcohol?
Denatured alcohol is ethanol that contains impurities making it undrinkable.
What is the typical composition of rubbing alcohol?
Rubbing alcohol usually contains about 70% isopropyl alcohol and 30% water.
What is the effect of the hydroxy proton in alcohols?
The hydroxy proton of an alcohol is weakly acidic.
What happens to alkoxide ions in the presence of a strong base?
A strong base can remove the hydroxy proton to give an alkoxide ion.
Which alcohol is more acidic: methanol or tert-butyl alcohol?
Methanol.
What is the relationship between acidity and alkyl group substitution in alcohols?
Acidity decreases as substitution on the alkyl group increases.
What enhances the acidity of alcohols?
Substitution by electron-withdrawing halogen atoms enhances the acidity.
How do alkoxide ions behave in chemical reactions?
Alkoxide ions are strong nucleophiles and strong bases.
What is the effect of phenol compared to cyclohexanol in terms of acidity?
Phenol is nearly 100 million times more acidic than cyclohexanol.
What historical figure used phenol as an antiseptic?
British surgeon Joseph Lister.
What factor contributes to the stability of the phenoxide ion?
The negative charge is delocalized over the oxygen and three carbon atoms of the ring.
What stabilizes the negative charge in a resonance hybrid involving oxygen?
The ability to spread the negative charge over four atoms rather than concentrating it on just one atom
This produces a more stable ion.
What is the pKa of phenol?
10.0
What happens when phenol reacts with sodium hydroxide?
Phenoxide anions are produced
The reaction is exothermic and favors the formation of sodium phenoxide.
What was phenol historically called due to its ability to neutralize common bases?
Carbolic acid
How is a nitro group (-NO2) related to charge stabilization?
It stabilizes a negative charge on an adjacent carbon atom through resonance.
What is the application of phenol in biochemistry?
It is used to separate cellular DNA from proteins.
What occurs when an aqueous phenol solution is used to isolate DNA?
DNA dissolves while proteins precipitate.
Name two nitrophenols that are much more acidic than phenol.
2-nitrophenol, 3-nitrophenol
Fill in the blank: Alcohols are important synthetic intermediates because they can be synthesized directly from a wide variety of other _______.
functional groups
What are the methods for synthesizing alcohols from alkenes?
- Acid-catalyzed hydration
- Oxymercuration-demercuration
- Hydroboration-oxidation
- Dihydroxylation
What is the common mechanism for nucleophilic substitution on an alkyl halide?
Usually via the SN2 mechanism
What do organometallic compounds contain?
Covalent bonds between carbon atoms and metal atoms
What is the significance of Grignard reagents in organic synthesis?
They are used to form carbon-carbon bonds.
Which type of compounds can Grignard reagents be made from?
Primary, secondary, and tertiary alkyl halides, as well as vinyl and aryl halides.
True or False: Alkyl fluorides generally react with Grignard reagents.
False
What is the reactivity order of halides in forming Grignard reagents?
R-I > R-Br > R-Cl»_space; R-F
What type of solvents are suitable for Grignard reactions?
Dry ethers such as diethyl ether
Other solvents may also be used, but they should not contain acidic protons.
What do Grignard and organolithium reagents act as when reacting with carbonyl groups?
Strong nucleophiles and strong bases
What is the first product formed when a Grignard reagent attacks a carbonyl compound?
An alkoxide ion
What type of alcohol is produced from the addition of a Grignard reagent to formaldehyde?
Primary alcohol
Fill in the blank: The formation of the Grignard reagent involves the reaction of an alkyl halide with _______ in an anhydrous ether solution.
Magnesium
What is the result of adding a Grignard reagent to a ketone?
An alkoxide salt, which can be protonated to form an alcohol.
What type of alcohol is formed when Grignard reagents add to formaldehyde?
Primary alcohol
Example: pentan-1-ol can be synthesized by adding a Grignard reagent to formaldehyde.
What are the products of Grignard reagent addition to aldehydes?
Secondary alcohols
The two alkyl groups of the secondary alcohol are from the Grignard reagent and the aldehyde.
How are tertiary alcohols formed using Grignard reagents?
By adding Grignard reagents to ketones
Tertiary alcohols have three alkyl groups bonded to the carbinol carbon.
What is the general reaction of Grignard reagents with acid chlorides?
They react to form tertiary alcohols after protonation
The reaction involves two equivalents of Grignard reagents.
What is the structure of an acid chloride?
R-C-Cl
In acid chlorides, the hydroxy group of the acid is replaced by a chlorine atom.
What are the steps involved in converting an acid chloride to a tertiary alcohol?
- Add Grignard reagent to form an unstable intermediate
- Expel a chloride ion to yield a ketone
- Add a second equivalent of Grignard reagent
- Protonate to form the tertiary alcohol
True or False: Grignard reagents can react with ethers.
False
Ethers are generally unreactive to Grignard reagents, but epoxides are exceptions due to ring strain.
What is the product when a Grignard reagent reacts with ethylene oxide?
Primary alcohols with two additional carbon atoms
The nucleophilic attack opens the epoxide ring.
What defines the carbinol carbon in alcohol synthesis?
The carbon atom with the OH group attached
The groups on this carbon determine the type of alcohol produced.
Fill in the blank: A secondary alcohol can be synthesized by adding a Grignard reagent to _______.
Aldehyde
What happens to the alkoxide ion during the reaction of acid chlorides with Grignard reagents?
It acts as a leaving group
This helps stabilize a negatively charged intermediate.
What is the result of adding two equivalents of Grignard reagents to a formate ester?
Secondary alcohols with two identical alkyl groups
Example: Ethyl formate reacts to form secondary alcohols.
What is the mechanism of Grignard reaction with esters?
- First equivalent forms an unstable intermediate
- Expels an alkoxide ion to yield a ketone
- Second equivalent reacts with the ketone to form a tertiary alcohol
What type of alcohol is formed when Grignard reagents add to ketones?
Tertiary alcohols
Fill in the blank: Grignard reagents added to _______ produce primary alcohols.
Formaldehyde
What is the significance of the carbinol carbon in alcohol synthesis?
It determines the type of alcohol produced based on the groups attached.
What type of alcohol is synthesized when a Grignard reagent reacts with a ketone?
Tertiary alcohol
Tertiary alcohols have three alkyl groups on the carbinol carbon.
True or False: The reaction of Grignard reagents with epoxides results in the new OH group being on the same carbon as the new bond.
False
The new OH group appears on the second carbon from where the Grignard formed a new bond.
What happens when an excess of ethylmagnesium bromide is added to methyl benzoate?
It forms 3-phenylpentan-3-ol
This is a result of two equivalents of Grignard reagents reacting with the ester.
What type of alcohol can be synthesized from a Grignard reagent reacting with a ketone?
Tertiary alcohol
What are Grignard reagents?
Organometallic compounds that are strong bases and nucleophiles
They are formed from alkyl halides and magnesium in dry ether.
What is the reaction of Grignard reagents with alkyl halides?
They do not easily displace halides, preventing undesired coupling products
This selectivity allows for the formation of Grignard reagents without side reactions.
What are lithium dialkylcuprates also known as?
Gilman reagents
They are used for coupling reactions with alkyl halides.
What is the general reaction for coupling with lithium dialkylcuprates?
R2CuLi + R’-X -> R-R’ + R-Cu + LiX
This reaction can couple two carbon chains efficiently.
How are lithium dialkylcuprates formed?
By the reaction of two equivalents of organolithium reagents with cuprous iodide
2 R-Li + CuI -> R2CuLi + LiI.
What is a significant characteristic of the reaction of lithium dialkylcuprates with vinyl halides?
They preserve the stereochemistry of the vinyl halide
This indicates that the mechanism does not involve SN2 reactions.
What is the reactivity of lithium dialkylcuprates towards carbonyl groups compared to Grignard reagents?
Less reactive towards carbonyl groups than Grignard reagents
They react slower with ketones than with acid chlorides.
What is the primary use of Grignard and organolithium reagents?
To react with carbonyl compounds to form alcohols
They add alkyl groups to carbonyl compounds.
What happens when Grignard reagents react with water?
They react vigorously and irreversibly, destroying the reagent
This necessitates the use of dry conditions.
What is the outcome of adding ethyllithium to water?
It produces ethane and destroys the reagent
Ethane bubbles to the surface due to its low acidity.
What types of groups are incompatible with Grignard and organolithium reagents?
O-H, N-H, S-H, and terminal alkyne groups
These groups can protonate the reagents.
What do sodium borohydride and lithium aluminum hydride reduce?
They reduce carbonyl compounds to alcohols
This involves adding hydrogen atoms across the C=O bond.
What is the difference between sodium borohydride and lithium aluminum hydride in terms of reactivity?
Lithium aluminum hydride is a stronger reducing agent
LAH can reduce less reactive carbonyl groups like acids and esters.
What is the mechanism of reduction for carbonyl groups using hydride reagents?
Hydride ion transfers to carbon, forming an alkoxide ion
Then, protonation of the alkoxide gives the alcohol.
What is a key feature of the reaction conditions for lithium aluminum hydride?
LAH and water are incompatible; water is added in a separate step
This prevents explosions and fires.
What type of alcohol does sodium borohydride produce from aldehydes?
Primary alcohols
It reduces ketones to secondary alcohols.
What is the result of using lithium aluminum hydride on carboxylic acids?
Reduces them to primary alcohols
LAH is effective on various carbonyl derivatives.
What is LAH and its primary function?
LAH (Lithium aluminum hydride) is a strong reagent that reduces ketones to secondary alcohols and aldehydes, acids, and esters to primary alcohols.
What is the primary use of sodium borohydride (NaBH4)?
NaBH4 is usually the best reagent for the reduction of a simple ketone or aldehyde.
What happens during the reduction of ketones and aldehydes using LAH?
LAH reduces ketones to secondary alcohols and aldehydes, acids, and esters to primary alcohols.
Fill in the blank: The reduction of an aldehyde or ketone produces a _______ or _______ alcohol.
primary or secondary
What is a key aspect of the reaction mechanism when using LAH?
The lithium salt of the alkoxide ion is formed first, followed by protonation with dilute acid.
True or False: Sodium borohydride can reduce acids and esters in the presence of a ketone or aldehyde.
False
What type of alcohol is produced when reducing an ester or carboxylate anion with LAH?
A primary alcohol.
What is the difference between oxidation and reduction in organic chemistry?
Reduction is the formation of a new C-H bond and a decrease in C-O bonds; oxidation is the opposite.
What are the two reducing agents mentioned for reducing carbonyl compounds?
- NaBH4
- LiAlH4
What is the role of Raney nickel in the hydrogenation process?
Raney nickel acts as a catalyst for the hydrogenation of ketones and aldehydes to alcohols.
What is the IUPAC naming convention for thiols?
IUPAC names for thiols are derived from alkane names using the suffix -thiol.
Fill in the blank: Thiols can be prepared by _______ reactions of sodium hydrosulfide with unhindered alkyl halides.
SN2
What is the significance of thiols in heavy metal poisoning treatment?
Thiols can complex with heavy metals, making them useful as antidotes, such as dimercaprol for arsenic poisoning.
True or False: Thiols are less acidic than alcohols.
False
What happens to thiols under oxidation conditions?
Thiols are oxidized to form disulfides.
What is the common name for methanethiol?
Methyl mercaptan.
What is the effect of introducing disulfide bonds in proteins?
It helps proteins withstand higher temperatures and maintain active conformation.
What is a common oxidant that can convert thiols to sulfonic acids?
KMnO4, nitric acid (HNO3), or bleach (NaOCl).
What is the structure of a disulfide bond?
R-S-S-R, formed from two thiol molecules.
What is the relationship between thiols and the characteristic odor of skunks?
Skunks spray thiols to protect themselves, which gives them their strong odor.
What is the pKa value of ethanethiol and ethanethiolate?
- Ethanethiol: 15.7
- Ethanethiolate: 10.5
What is the primary alcohol produced from the reduction of benzaldehyde?
Benzyl alcohol.
What do enzymes contain to remove protein and blood stains?
Enzymes contain the ability to remove protein and blood stains by replacing strategically located amino acid residues with cysteines
Modified enzymes maintain their active conformation in hot water.
What is the structure of a disulfide bridge?
A disulfide bridge involves two cysteine residues linked by a sulfur-sulfur bond.
This structure is represented as R-S-S-R.
What happens during vigorous oxidation of thiols?
Vigorous oxidation converts thiols to sulfonic acids.
Oxidants such as KMnO4, nitric acid (HNO3), or bleach (NaOCl) can facilitate this reaction.
How many electrons can sulfur have in an expanded octet?
Sulfur can have 10 or 12 electrons in an expanded octet, as seen in SF4 (10 electrons) and SF6 (12 electrons).
What is the general formula for a thiol?
The general formula for a thiol is R-S-H.
What is glutathione and its function?
Glutathione is a tripeptide containing a thiol group that serves as a mild reducing agent to detoxify peroxides and maintain cysteine residues in hemoglobin.
It can also detoxify alkylating agents.
What are acid derivatives?
Acid derivatives are compounds related to carboxylic acids with other electron-withdrawing groups instead of the -OH group.
Examples include acid chlorides, esters, and amides.
How are alcohols classified?
Alcohols are classified as primary, secondary, or tertiary based on the carbon atom to which the hydroxy group is attached.
This classification depends on whether the carbon is primary, secondary, or tertiary.
What is a sulfonic acid?
A sulfonic acid is a strongly acidic compound with the formula R-SO3H, formed by the vigorous oxidation of a thiol.
It is characterized by the presence of a sulfonic group.
What is the role of Grignard reagents in alcohol synthesis?
Grignard reagents are used to synthesize primary, secondary, and tertiary alcohols by reacting with carbonyl compounds.
They are organometallic reagents of the form R-MgX.
What defines a primary alcohol?
A primary alcohol is defined as having the hydroxy group attached to a primary carbon atom.
What is the structure of a ketone?
A ketone has the structure R-C(=O)-R’, where R and R’ are alkyl or aryl groups.
What is a diol?
A diol is a compound with two alcohol -OH groups.
The term glycol is commonly used for 1,2-diols.
What is a mercaptan?
A mercaptan is the sulfur analogue of an alcohol, represented as R-SH.
What is the significance of lithium dialkylcuprate in organic chemistry?
Lithium dialkylcuprate is used to couple with alkyl halides in organic synthesis.
It is also known as a Gilman reagent.
What does the term ‘hydrophilic’ mean?
Hydrophilic means being attracted to water and water-soluble.
What does the term ‘hydrophobic’ mean?
Hydrophobic means being repelled by water and water-insoluble.
What is the general reaction for reducing carbonyl groups using hydride reagents?
The general reaction involves hydride reagents reducing carbonyl groups to form alcohols.
What are essential problem-solving skills in organic chemistry?
Essential skills include drawing structures, predicting boiling points, converting compounds to alcohols, and proposing syntheses.
Specific problems illustrate these skills.
What is the difference between an aldehyde and a ketone?
An aldehyde has one hydrogen and one alkyl group on the carbonyl carbon, while a ketone has two alkyl groups.
Example: Formaldehyde (H2C=O) is an aldehyde.
What is the structure of l-phenylbutan-1-ol?
A primary alcohol with a phenyl group attached to the first carbon of a butanol chain
Primary alcohols have the hydroxyl (-OH) group attached to a carbon atom that is attached to only one other carbon atom.
What is the product of the synthesis of l-phenylbut-1-ene?
An alkene formed from the dehydration of l-phenylbutan-1-ol
Alkenes are characterized by at least one carbon-carbon double bond.
What is the synthesis pathway for l-phenylbutan-2-ol?
Reduction of l-phenylbutan-2-one or Grignard addition to a ketone
Grignard reagents are used to form alcohols by adding to carbonyls.
How can you synthesize 2-phenylpentan-2-ol?
By reducing 2-phenylpentan-2-one or via Grignard reaction with appropriate starting materials
2-phenylpentan-2-ol is a secondary alcohol.
What is the role of Grignard reagents in synthesizing alcohols?
They react with carbonyl compounds to form alcohols
Grignard reagents are organomagnesium compounds that act as nucleophiles.
Fill in the blank: 1-cyclohexylethanol can be prepared from _______.
[acetaldehyde, CH3CHO]
This involves the reaction of a Grignard reagent with acetaldehyde.
True or False: Vinyl alcohols are stable compounds.
False
Vinyl alcohols rapidly isomerize to carbonyl compounds.
What is the mechanism for the acid-catalyzed loss of water from propane-2,2-diol?
Protonation of the hydroxyl group followed by elimination of water to form acetone
This process involves carbocation rearrangement.
Explain the isomerization mechanism of vinyl alcohol to acetaldehyde.
Protonation of the alcohol followed by rearrangement to form the carbonyl
The reaction is favored due to the stability of the carbonyl compound.
What happens when compound A (C7H11Br) reacts with magnesium in ether?
It forms the Grignard reagent B (C7H11MgBr)
This is a standard method for preparing Grignard reagents.
What is the expected product when Grignard reagent B reacts with acetone?
D (C10H18O), a tertiary alcohol
The reaction involves nucleophilic attack on the carbonyl carbon of acetone.
What is the effect of using dilute hydrogen peroxide in removing skunk oil?
Oxidizes thiols to sulfonic acids, neutralizing the odor
Skunk oil primarily contains 3-methylbutane-1-thiol and but-2-ene-1-thiol.
How can 1-methylcyclohexanol be synthesized?
From methylenecyclohexane using hydrogenation and other reagents
Hydrogenation typically involves the addition of H2 across double bonds.
Compare the properties of propan-2-ol and its hexafluoro analog.
Propan-2-ol has a boiling point of 82 °C, while the hexafluoro analog has a boiling point of 58 °C
Differences in molecular weight and dipole moments influence boiling points.
Why is the hexafluoro analog a stronger acid than propan-2-ol?
Due to the electron-withdrawing effect of fluorine atoms
Electron-withdrawing groups stabilize the conjugate base.
What reagent can be used to introduce deuterium into organic compounds?
LiAlD4
LiAlD4 is a reducing agent equivalent to LiAlH4 but provides deuterium instead of hydrogen.
How can 2-phenylethanol be synthesized from formaldehyde?
By adding formaldehyde to a suitable Grignard reagent
Formaldehyde acts as the electrophile in this reaction.
What is the result of ozonolysis reactions using pyridine as a solvent?
Generates aldehydes and ketones without isolating intermediates
This method allows for more efficient synthesis of carbonyl compounds.
