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Chapter 10
Structure and Synthesis of Alcohols

10-01

Title	Structure of Water and Methyl Alcohol
Caption	The structure of methanol resembles that of water, with an alkyl group replacing one of the hydrogen atoms of water.
Notes	The H-O-H angle in water is 104.5o. The C-O-H angle in methyl alcohol is 108.9o.
Keywords	methyl alcohol

10-02

Title	Types of Alcohols
Caption
Notes	Alcohols are classified according to the type of carbon the hydroxyl group is attached to. Alcohols in which the hydroxyl group is attached to a primary carbon are considered primary alcohols. A secondary alcohol has the hydroxyl group attached to a secondary carbon, and a tertiary alcohol is attached to a tertiary carbon. A hydroxyl group attached to a methyl group is known as methyl alcohol.
Keywords	primary alcohol, secondary alcohol, tertiary alcohol, methyl alcohol

10-02-018UN

Title	Synthesis of 1,2-Diols
Caption
Notes	An alkene can be oxidized to the vicinal diol by using peroxyacids, osmium tetroxide or potassium permanganate. Vicinal diols are commonly known as glycols.
Keywords	vicinal diol, glycol

10-02-023UN

Title	Boiling Points of Alcohols
Caption
Notes	Alcohols have higher boiing points than ethers and alkanes because alcohols have dipole-dipole interactions and can form hydrogen bonds. The stronger interaction between alcohol molecules will require more energy to break them resulting in a higher boiling point.
Keywords	dipole-dipole, hydrogen bond

10-02-024UN

Title	Hydrogen Bonding in Alcohols
Caption
Notes	The hydroxyl proton of the alcohol has a partial positive charge. This hydrogen can interact with the lone pairs of oxygen of a different alcohol molecule. This interaction between hydrogen and oxygen is called a hydrogen bond. In contrast, ethers cannot form hydrogen bonds because the hydrogens on the carbons are not partially positive.
Keywords	hydrogen bond

10-02-025UN

Title	Hydrophobic and Hydrophilic Regions of Alcohols
Caption
Notes	The alkyl chain of an alcohol is considered the hydrophobic region ( or "water hating") because there is no interaction between the carbons on the chain and water molecules. The hydroxyl end of the alcohol can interact well with water (hydrogen bonding) so this end is considered hydrophilic or "water loving."
Keywords	hydrophilic, hydrophobic

10-02-029UN

Title	Acidity of Alcohols
Caption
Notes	The hydroxyl proton of an alcohol can be abstracted by a base to form the alkoxide ion. Although some of the alcohols are about as acidic as water, adding electron-withdrawing groups will increase the acidity. Phenols are much more acidic than open-chained alcohols because the aromatic ring can effectively delocalize the negative charge within the aromatic ring.
Keywords	acidity, phenol, alkoxide ion

10-02-030UN

Title	Formation of Potassium or Sodium Alkoxides
Caption
Notes	Alcohols react with sodium and potassium metal to form alkoxides. Ethanol, for example, reacts with sodium to form sodium ethoxide, a strong base commonly used for elimination reactions. More hindered alcohols like 2-propanol or tert-butanol react faster with potassium than with sodium. The reaction produces hydrogen gas.
Keywords	alkoxides, sodium ethoxide

10-02-031UN

Title	Acidity of Phenols
Caption
Notes	The aromatic alcohol phenol is more acidic than aliphatic alcohols due to the ability of aromatic rings to delocalize the negative charge of the oxygen within the carbons of the ring.
Keywords	aromatic alcohol, phenol, delocalization

10-02-032UN

Title	Charge Delocalization on the Phenoxide Ion
Caption
Notes	The negative charge of the oxygen can be delocalized over four atoms of the phenoxide ion. There are three other resonance structures that can localize the charge in three different carbons of the ring. The true structure is a hybrid between the four resonance forms.
Keywords	phenoxide ion, resonance, resonance hybrid

10-02-044UN

Title	Organometallic Reagents for Alcohol Synthesis
Caption
Notes	Terminal alkynes can be deprotonated by strong bases such as sodium amide to form acetylide ions. The acetylide ion is a strong nucleophile that can react with alkyl halides and carbonyl compounds forming a C-C bond. The reaction of the acetylide ion with aldehydes and ketones produces acetylenic alcohols.
Keywords	terminal alkyne, acetylide ion, nucleophile

10-02-045UN

Title	Grignard Reagents
Caption
Notes	Grignard reagents are prepared by reacting the alkyl halide with magnesium metal in an ether solvent. There are no restrictions on the alkyl halides used but alkyl iodides are the most reactive followed by bromides and chlorides. It is not typical for an alkyl fluoride to form Grignard reagents. The order of reactivity for alkyl halides is R-I > R-Br > R-Cl >> R-F.
Keywords	Grignard reagent

10-02-050UN

Title	Addition of Organometallics to Carbonyl Compounds
Caption
Notes	Grignard and lithium reagents have a nucleophilic carbon and as such can attack an electrophile in solution. The carbonyl carbon has a partial positive charge that will be prone to nucleophilic attacks. Attack of the organometal carbon on the carbonyl will produce a tetrahedral intermediate with a negatively charged oxygen atom, i.e., an alkoxide. Protonation of the intermediate with dilute acid gives the alcohol.
Keywords	Grignard reagents, lithium reagents, nucleophile, electrophile, tetrahedral intermediate.

10-02-051UN

Title	Protonation of the Alkoxide Intermediate
Caption
Notes	The intermediate alkoxide can be protonated by using a dilute acid solution.
Keywords	alkoxide, protonation

10-02-052UN

Title	Mechanism of Grignard Reactions
Caption
Notes	The nucleophilic carbon of the Grignard will attack the electrophilic carbon of the carbonyl producing the magnesium alkoxide salt. In a separate step, water or dilute acid is added to protonate the alkoxide and form the alcohol.
Keywords	Grignard, alkoxide, protonation

10-02-054UN

Title	Formation of Primary Alcohols Using Grignard Reagents
Caption
Notes	Depending on the carbonyl compound used primary, secondary or tertiary alcohols can be obtained. Reaction of a Grignard with formaldehyde will produce a primary alcohol after protonation.
Keywords	primary alcohol

10-02-059UN

Title	Formation of Secondary Alcohols Using Grignard Reagents
Caption
Notes	Addition of a Grignard reagent to an aldehyde followed by protonation will produce a secondary alcohol.
Keywords	secondary alcohol

10-02-062UN

Title	Formation of Tertiary Alcohols Using Grignard Reagents
Caption
Notes	Tertiary alcohols can be easily obtained by addition of a Grignard to a ketone followed by protonation with dilute acid.
Keywords	tertiary alcohol

10-02-067UN1-2

Title	Reaction of Grignards with Carboxylic Acid Derivatives
Caption
Notes	Acyl chlorides and esters will react with two equivalents of Grignard to form tertiary alcohols with two identical groups. The first equivalent will add to the carbonyl and produce a ketone which will react with a second equivalent of Grignard to give the tertiary alcohol after acidic work-up.
Keywords	acyl chlorides, esters, Grignard reagent

10-02-068UN1-2

Title	Reaction of Grignards with Carboxylic Acid Derivatives
Caption
Notes	Acyl chlorides and esters will react with two equivalent of Grignards to form tertiary alcohols with two identical groups. The first equivalent will add to the carbonyl and produce a ketone which will react with a second equivalent of Grignard to give the tertiary alcohol after acidic work-up.
Keywords	acyl chlorides, esters, Grignard reagent

10-02-070UN

Title	Mechanism of Grignard Addition
Caption
Notes	The first step of the reaction is the attack of the Grignard on the carbonyl compound to form the tetrahedral intermediate. The negative charge on the oxygen goes back to form a carbon oxygen double bond forcing a methoxide ion out of the molecule and forming a ketone. The ketone reacts with a second equivalent of Grignard to form an alkoxide. Since there are no good leaving groups in the molecule the alkoxide will be protonated to give the tertiary alcohol. Notice that since two equivalents of Grignard were added, two of the alkyl groups of the alcohol will be exactly the same.
Keywords	Grignard, equivalent, alkoxide

10-02-074UN

Title	Addition to Ethylene Oxide
Caption
Notes	Grignard and lithium reagents will attack epoxides (also called oxiranes) and open them to form alcohols. This reaction is favored because the ring strain present in the epoxide is relieved by the opening. The reaction is commonly used to extend the length of the carbon chain by two carbons.
Keywords	epoxides, oxiranes, ring strain

10-02-076Summ

Title	Summary of Grignard Reactions
Caption
Notes	Primary and secondary alcohols can be synthesized by addition of Grignards to formaldehyde and aldehydes, respectively. A second way to make primary alcohols is the addition of a Grignard to ethylene oxide. This reaction will add carbons to the chain.
Keywords	primary alcohols, secondary alcohols

10-02-077Summ

Title	Summary of Grignard Reactions: Tertiary Alcohols
Caption
Notes	Tertiary alcohols can be prepared by the attack of Grignard reagents with ketones, acyl chlorides and esters. When acyl chlorides and esters are used the alcohol will have two identical alkyl groups.
Keywords	tertiary alcohols, ketones, acyl chlorides, esters

10-02-090UN

Title	Hydride of Carbonyl Groups
Caption
Notes	Carbonyl compounds can be reduced to alcohols by using hydride reagents such as sodium borohydride (NaBH4) and lithium aluminum hydride (LiAlH4 or LAH). The nucleophile, a negatively charged hydrogen (hydride), will attack the carbonyl carbon of ketones and aldehydes to produce primary or secondary alcohols after protonation.
Keywords	sodium borohydride, lithium aluminum hydride, hydride

10-02-092UN

Title	Ease of Reduction of Carbonyl Compounds
Caption
Notes	Although sodium borohydride and lithium aluminum hydride reduce ketones and aldehydes to their corresponding alcohols, only lithium aluminum hydride is capable of reducing esters and carboxylic acids to alcohols. This makes sodium borohydride a selective reagent for reductions when there is more than one type of carbonyl present in the molecule.
Keywords	sodium borohydride, lithium aluminum hydride, hydride

10-02-103UN

Title	Catalytic Hydrogenation of Ketones and Aldehydes
Caption
Notes	The carbonyl group of ketones and aldehydes can be reduced by catalytic hydrogenation by using Raney nickel as catalyst. Raney nickel is a hydrogen rich nickel powder that is more reactive than Pd or Pt catalysts. This reaction is not commonly used because it will also reduce double and triple bonds that may be present in the molecule. Hydride reagents are more selective so they are used more frequently for carbonyl reductions.
Keywords	Raney nickel, catalyst

10-02-116UN

Title	Nucleophilic Substitution with Thiols
Caption
Notes	Sodium hydrosulfide can attack unhindered alkyl halides to form thiols.
Keywords	Sodium hydrosulfide, thiols

10-02-117UN

Title	Oxidation of Thiols
Caption
Notes	Thiols can be oxidized to form disulfides. This is a reversible process and the disulfide can be reduced by using zinc in HCl. This reaction is common in amino acid chemistry where the disulfide links are part of a protein's primary structure.
Keywords	thiols, disulfide, oxidations, reduction

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