Organic - Chapter 3: Alcohols, Phenols, & Ethers

Hydroxy Group

Hydroxy Group

The -OH functional group.

R Groups

Indicate carbon groups; R&R can be the same or different groups.

Alcohols

Have an -OH group attached to an aliphatic carbon (C-OH).

R-OH

General Formula of Alcohols

Phenols

Have an -OH group on a benzene ring (an aromatic alcohol).

C6H5OH

General Formula of Phenol

Ethers

Have the functional group C-O-C.

R-O-R

General Formula of Ether

large

Alcohols, Phenols, and Ethers are important organic compounds that occur naturally and are produced synthetically in ____ amounts.

Ethanol

(drinking alcohol) has been used since ancient times.

peppermint oil

Menthol is a ten-carbon alcohol found in __________; it is used widely as a flavoring agent.

Cholesterol

An important biological molecule and has been implicated in some forms of heart disease.

H2O

Alcohols, phenols, and ethers may be considered to be derived from ____.

alkyl group

In alcohols one of water's hydrogens is replaced with an ______.

aromatic ring

In phenols one of water's hydrogens is replaced with an _________.

both

In ethers ______ of water's hydrogens are replaced with alkyl groups.

Alcohol Nomenclature

1.) Name the longest carbon chain to which the -OH group is attached. Use the hydrocarbon name of the chain, drop the final -e and replace it with -ol. 2.) Number the longest carbon chain to give the lowest number to the carbon with the attached -OH. 3.) Locate the -OH position and locate/name any other groups attached to the longest chain. 4.) Combine the name and location of other groups, the location of the -OH, and the longest chain into the final name.

common names

Some of the simpler alcohols are often known by ________; in these names the alkyl group is followed by the word alcohol.

Phenol Nomenclature

Substituted are usually named as derivatives of the parent compound phenol.

chemistry

The ______ of alcohols often depends on the groups bonded to the carbon with the hydroxy on it.

attached group

There are three classifications of alcohols; these classifications are based on the alcohol's ________.

Primary Alcohols

The carbon with the hydroxy group is attached to one other carbon atom and two hydrogen atoms.

Secondary Alcohols

The carbon with the hydroxy group is attached to two other carbon atoms and one hydrogen atom.

Tertiary Alcohols

The carbon with the hydroxy group is attached to three other carbon atoms and no hydrogens.

polar

The -OH group of alcohol is ______ and capable of hydrogen bonding.

True

T or F: Hydrogen bonding in alcohols makes low molecular weight alcohols highly soluble in water.

alkane

As the size of the alkyl group in an alcohol increases, the physical properties become less water-like and more _____-like.

hydrophobic

Larger alkanes have greater _______ regions and are less soluble or insoluble in water.

Solubility Ratio

1 hydroxy for every 5 carbons.

carbon

The number of _____ atoms per hydroxy group determines the solubility in water.

boiling point

Hydrogen bonding can affect __________.

high

The -OH group in alcohol can hydrogen bond between alcohol molecules leading to relatively _____ boiling points.

alcohols

When compared to molecules of similar molecular weight, ______ have much higher boiling points.

Dehydration

The removal of water from an alcohol.

Dehydration to Produce an Alkene

(180 degrees C) An elimination reaction, uses Markovnikov's rule.

Elimination Reaction

A reaction when two or more bonds are broken to form a new multiple bond.

False

T or F: Only one product can be formed in dehydration to produce an alkene.

principle

The major/______ alkene produced is the one in which the higher number of carbon groups is bonded to the double-bonded carbon atoms.

living systems

Alcohol dehydration is important in __________.

Enzymes

_______ (rather than sulfuric acid) are the catalysts in alcohol dehydration.

Dehydration to Produce an Ether

(140 degree C) A dehydration reaction occurs between two alcohol molecules where an -H is removed from one alcohol, an -OH group is removed from the other and they combine to make water. Leaving the two remaining fragments to bond.

Primary Alcohols

Ether-forming reactions are useful mainly with _________.

living organisms

Dehydration synthesis is important in ________ because it is part of the formation of carbohydrates, fats, proteins, and other essential substances.

temperature

The type of dehydration is controlled by ________.

Oxidation Reactions

When a molecule gains oxygen atoms or loses hydrogen atoms.

two

Alcohols can be oxidized by removing ____ hydrogen atoms.

oxidizing agents

Alcohol oxidations can be accomplished with an __________ (O) such as K2Cr2O7 or KMnO4.

carboxylic acid

Primary alcohols --> aldehyde --> __________

ketone

Secondary alcohols --> _________

no reaction

Tertiary alcohols --> __________

useful

Alcohols can be converted by chemical reactions into a wide variety of other ______ products.

False

T or F: Most alcohols occur naturally in commercial quantities therfore they are prepared from alkenes.

Nature

_______ also employs multistep reactions to carry out processes essential to life.

protonated alcohol

During alcohol dehydration mechanism, the H+ ion becomes bonded to the oxygen resulting in a _________.

Methanol

(methyl alcohol) known as wood alcohol because historically it was produced by the distillation of wood. Useful as a solvent and industrial starting material due to its oxidation product formaldehyde. Highly toxic, can cause blindness.

CH3OH

Formula of Methanol

Ethanol

(ethyl alcohol, grain alcohol) the active ingredient in alcoholic beverages. Produced commercially from ethylene and through biological fermentation of carbohydrates. Used in pharmaceuticals as a solvent and in aftershave lotions as an antiseptic and skin softener. It is an important industrial starting material and used in fuels such as gasohol.

Gasohol

Mixture of gasoline and ethanol.

CH3CH2OH

Formula of Ethanol

2-Propanol

(isopropyl alcohol) the main component of rubbing alcohol. Acts as an astringent on the skin causing the skin tissue to contract, harden, and limit secretions. Lowers skin temperature by rapidly evaporating from the skin. It is extremely poisonous and shouldn't be taken internally.

1,2,3-Propanetriol

(glycerol or glycerin) has three hydroxy groups making it useful for many things. The hydrogen bonding resulting from the three hydroxy groups causes it to a syrupy/high-boiling point liquid with an affinity for water. Used as a food moistening agent, good for soaps, and to retain water that maintains the freshness of cut flowers.

1,2-Ethanediol

(ethylene glycol) high-boiling point liquid that is completely miscible with water (hydrogen bonding). Used as antifreeze and a starting material for the manufacture of polyester fibers.

1,2-Propanediol

(propylene glycol) high-boiling point liquid that is completely miscible with water (hydrogen bonding). Used as antifreeze and a starting material for the manufacture of polyester fibers.

colorless

Phenol is a ______, low-melting-point solid with a medicinal odor.

carbolic acid

Adding a small amount of water to Phenol causes the solid to liquefy (this mixture is commonly called _________).

weak acids

Unlike alcohols, phenols behave as _________ in water (these acids can chemically burn the skin).

salts

Phenols can also react with bases to form ______.

Joseph Lister

In the late 1800's an English surgeon named _________ introduced phenols as a hospital antiseptic (before that time antiseptics were not used and few patients survived even minor surgeries).

4-chloro-3,5-dimethylphenol

Nonirritating topical antiseptic

4-hexylresorcinol

Used in mouthwashes and throat lozenges.

disinfectants

Some phenol derivatives are used as ________.

Lysol

O-phenylphenol and 2-benzyl-4-chlorophenol are the active ingredients in ______.

food

Some phenol derivatives are used as antioxidants in _____.

Antioxidants

Agents that interfere with oxidizing reactions, protect food from spoilage and other unwanted reactions.

BHA & BHT

_________ are widely used in the packaging materials for foods that might turn rancid (they are listed as food ingredient that "will maintain freshness").

Naming Ethers

Name the smaller of the two R groups as an alkoxy group attached to the parent chain by replacing the -yl ending of the R group with -oxy.

Common Names of Ethers

Name the groups attached to the oxygen alphabetically and add the word ether. If the groups are the same use the prefix di-.

Heterocyclic Rings

Contain atoms of elements other than carbon in the ring (many biological molecules have these rings).

carbohydrates

Many ________ contain cyclic ethers.

Cyclic Ethers

Rings containing oxygen

Furan

Common cyclic ether:

Pyran

Common cyclic ether:

less

Ethers are much _____ polar than alcohols because oxygen is bonded to two carbons rather than a hydrogen.

alkanes

Ethers can hydrogen bond to water, making them more soluble than _____.

low

Ethers cannot hydrogen bond with other ethers, therefore they have ____ boiling and melting points and are less soluble in water than alcohols.

inert

Ethers are ____ and do not react with most reagents (like alkanes) making them a useful solvent.

flammable

Ethers are highly ______ (like alkanes).

Thiols

Contain a sulfhydryl group (-SH).

6A

Sulfur and oxygen belong to the same group (___) on the periodic table so they react similarly.

analogous

The sulfhydryl group in thiols is ________ to the hydroxy group in alcohols.

Disulfides

Compounds containing an -S--S- linkage.

odor

The most distinguishing characteristic of thiols is their strong and offensive _____. Ex.) skunks, stink bugs, onions, garlic, etc.

flavors

Some thiols have less offensive odors and some are _____.

1-propanethiol

The odor in freshly chopped onions.

1-propane-3-thiol

Responsible for the odor and flavor of garlic.

3,3-di-(1-propenyl)

______disulfide is responsible for the odor and flavor of garlic.

Ethanethiol

(CH3CH2-SH) added to natural gas (methane) to make it possible to detect a gas leak.

Oxidizing Thiols

Forms disulfide (-S--S-) linkage. General Formula: 2R -- SH + (O) ----> R--S--S--R + H2O

Disulfide Reduction

Oxidation reactions can be reversed with a reducing agent (H). The disulfides are uncoupled to produce thiols. General Reaction: R--S--S--R + 2(H) ------> 2R--SH

Heavy Metal Reaction

Metal ions react with the sulfhydryl group. General Reaction: 2R--SH + M2+ ------> R--S--M--S--R + 2H+