j mcm-oc-pharmacy-fm-1-03

8/7/2019 J McM-OC-Pharmacy-Fm-1-03

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Organic ChemistryOrganic Chemistry

LaboratoriumLaboratorium KimiaKimia OrganikOrganik JurusanJurusan KimiaKimia

FakultasFakultas MatematikanMatematikan dandan IlmuIlmu PengetahuanPengetahuan AlamAlam

UniversitasUniversitas PadjadjaranPadjadjaran

20092009

Some Compounds with Oxygen, Sulfur, or HalogensSome Compounds with Oxygen, Sulfur, or Halogens


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Some Compounds with Oxygen, Sulfur, or Halogen

1. How do alcohols, phenols, and ethers compare with water and alkanes?

Be able to describe the major differences in properties among members of

these families.

2. What are the distinguishing feature of ethers, sulfur-containing compounds, and

halogen-containing compounds?Be able to describe the structures and outstanding properties of compounds

with these functional groups.

3. How are alcohols, phenols, ether, sulfur-containing compounds, and halogen-

containing cmpounds named?

Be able to give systematic names for the simple members of these families and

write their structures, given the names.4. What are the general properties of alcohols and phenols?

Be able to describe such properties as polarity and hydrogen bonding, water

solubility, and boiling points.

5. What are alcohols and phenols weak acids?

Be able to show why alcohols and phenols are acids.


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6. What are the major chemical reactions of alcohols?

Be able to describe and predict the products of the dehydration and oxidation

of alcohols.

7. What are some of the significant application of alcohols, phenols, ethers, sulfur-

containing compounds, and halogen-containing compounds ?

Be able to describe and predict the products of the dehydration and oxidation

of alcohols.

Some Compounds with Oxygen, Sulfur, or Halogen


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Alcohols, Phenols, and Ethers

Alcohol, a compound that contains an OH functional group covalently

bonded to an alkane-like carbon atom (ROH).

Hydroxyl group, a name for the OH group in an organic compound.

Phenol, a compound that has an OH functional group bonded directly to

an aromatic, benzene-like ring.

Eteher, acompound that has an oxygen atom bonded to two carbon atoms

(ROR).


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Ethyl alcohol, dimethyl ether, and propane have similar molecular weights, yet

ethyl alcohol boils more than 100rC higher than the other two.

In fact, the boiling point of ethyl alcohol is close to that of water.

Why should this be?


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The formation of hydrogen bonds in water (a) and alcohols (b).

Due to the attractive forces of the hydrogen bonds, the easy escape of

molecules into the vapour phase is prevented, resulting in high boiling points.

a b


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Some Common Alcohols

Methyl Alcohol (CH3OH, Methanol), the simplest alcohol, is commonly known

as wood alcohol because it was once prepared by heating wood in the

absence of air.

Today it is made in large quantities from a mixture of carbon monoxide and

hydrogen,

Ethyl Alcohol (CH3CH2OH, Methanol), is one of the oldest known pure organic

chemicals, and it production by fermentation of grain and sugar goes back for

many thousans of years.

Sometimes called grain alcohol, ethyl alcohol is the alcohol present in alltable wines (10-13%), beers (3-5%), and distilled liquors (35-90%).

During fermentation, starches or complex sugars are converted to simple

sugars (C6H12O6) which are then converted to ethyl alcohol:


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Some Common Alcohols

Isopropyl Alcohol ((CH3)2CHOH, Isopropanol) or rubbing alcohol, is usedas a

70% mixture with water for rubdowns because it cools the skin throughevaporation and causes pors to close.

Its also used as a solvent for medicines, as a sterilant for instrument, and to

cleanse the skin before drawing blood or giving injection.

Ethylene Glycol (HOCH2CH2OH), a dialcohol, ethylene glycol is a colorless liquidmiscible with water and insoluble in non-polar solvent.

Its two major uses are in antifreeze and in making polymer film and fiber such

as Dacron.

Glycerol (HOCH2CH(OH)CH2OH), the trialcohol glycerol is a colorless liquid that

is miscble with water.Unlike ethylene glycol, its not toxic but has a sweet taste thats put to use in

candy and prepared foods.

Glycerol, often called glycerin, is also used in cosmetic and tobacco as a

moisturizer, in plasctics manufacture, in antifreeze and shock absorber fluids,

and as a solvent.


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Naming Alcohols

Alcohol are classified according to the number of carbon substituentsbonded to the hydroxyl-bearing carbon.

Primary alcohol, an alcohol in which the OH-bearing carbon atom is bondedto one other carbon (and two hydrogens), RCH2OH.

Secondary alcohol, an alcohol in which the OH-bearing carbon atom isbonded to two other carbon (and one hydrogens), R2CHOH.

Tertiary alcohol, an alcohol in which the OH-bearing carbon atom is bonded

to three other carbon (and no hydrogens), R3COH.


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Naming Alcohols

Step 1. Name the parent compound

Find the longest chain containing the hydroxyl group and name the chain by

replacing the e ending by of the corresponding alkane with ol.

If the compound is cyclohexane, its name provides the root name, for example, the

cyclohexanol

Step 2. Number the carbon atoms in the main chain.

Begin at the end nearer the hydroxyl group, ignoring the location of other

substituents

In an OH-substituted cycloalkane, begin with the OH group


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Naming Alcohols

Step 3. Identify and number the hyroxyl group and the substituents

Step 4. Write the full name

Place the number that

locates the hydroxyl group

immediately before the

parent compound name

(with the-ol ending).

Number all other

substituents according to

their positions and list

them alphabetically.


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Properties of Alcohols


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Alcohols are hydrogen-bonded and higher boiling than similar alkanes.

Common alcohols are liquids.

Lower alcohols are miscible with water; higher dialcohols are more

water-soluble than similar monoalcohols.

Alcohols are very weak acids (proton donors); water solution are neutral.

Common alcohols are flammable; can be toxic.

Dehydration and oxidation are major alcohol reactions.

Hdyrogen bonding is the major influence on the physical properties of

alcohols.

Straight-chain alcohols with up to 2 carbons atoms are liquids, and each

boils at a higher temperature than similar alkanes.

Low-molecular-weight alcohols such as methanol and ethanol are water-

like in their solubility behaviour.

Methanol and ethanol are both infinitely solble i water, with which theycan form hydrogen bonds.

Higher-molecular-weight alcohols, such as 1-heptanol, however, are

much more alkane-like and less water-like.


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Alcohols with two or more OH groups can form more than onehydrogen bond

They are therefore higher boiling and water-soluble than similar alcohols

with one OH group.


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Chemical Reactions of Alcohols

Dehydration of Alcohols

Alcohls undergo loss of water (dehydration) on treatmen with a strong acidcatalyst. The OH group is lost from adjacent carbon to yield an alkene

product:


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Dehydration of Alcohols

Alcohls undergo loss of water (dehydration) on treatmen with a strong acidcatalyst. The OH group is lost from adjacent carbon to yield an alkene

product:

In cases wheremore than one alkene can result from dehydration, amixture of products is usually formed.

A good rule of thumb is that the major product is the one that has the

greater number of alkyl groups attached to the double-bond carbons.


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Oxidation of Alcohols

Primary and secondary alcohols are converted into carbonyl-containingcompounds on treatment with oxidizing agent.

Carbonyl group is a functional group that has a carbon atom joined to an

oxygen atom by a double bond, C=O.

Oxidizing agents: potassium permanganate (KMnO4)

Sodium dichromate (Na2Cr2O7)

Ntric acid (HNO3)

Well simply use the symbol [O] to indicate a generalized reagent.


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Primary and secondary alcohols are converted into carbonyl-containingcompounds on treatment with oxidizing agent.

The net effect of an alcohol oxidation is the removel of two hydrogenatoms.

One hydrogen comes from the OH group, and the other comes from

the carbon atom bonded to the OH group.

This hydrogens are converted into water during the reaction by the

oxidizing agent [O].


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Primary and secondary alcohols are converted into carbonyl-containing

compounds on treatment with oxidizing agent.

Different kind of carbonyl-containing product are formed depending on

the structure of the starting alcohol and on the exact reaction conditions.

Thus, primary alcohols (RCH2H) are converted either into aldehyde

(RCH=O) if carefully controlled conditions are used, or into carboxylic

acids (RCOOH) if an excess of oxidant is used.


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Secondary alcohols (R2CHOH) are converted into ketones (R2C=O) on

treatment with oxidizing agents.


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Tertiary alcohols (R3COH) dont normaly react with oxidizing agents

because they dont have a hydrogen on the carbon atom next to the

OH group.


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Alcohol oxidation are critically important steps in many biological

processes, example:

When lactic acid builds up in tired, overworked muscles, the liver removes

it by oxidizing it to pyruvic acid. Our bodies, of course, dont use Na2Cr2O7 or KMnO4 for the oxidation;

they use specialized, highly selective enzymes to carry out their

chemistry


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Phenols

The word phenol is the name both of a specific compound

(hydroxybenzene, C6H5OH) and of a family of compounds. The medical use of phenol is now restricted because it can cause severe

skin burns and has been found to be toxic, both by ingestion and by

absorption through the skin and inhalation.

Phenols and substituted phenols such as the cresols (methylphenols) are

common as desinfectants in hospital and elsewhere.


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Phenols

Phenols are usually named with the ending-phenol rather than benzene,

for example:

The properties of phenols, like those of alcohols, are influenzed by

hydrogen bonding.

Most phenols are water-soluble to some degree and have higher melting

point and boiling points than similarly substituted alkylbenzenes.


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Acidity of Alcohols and Phenols

Alcohols and phenols are weakly acidic. They dissociate only slightly in

aqueous solution and therefore establish equilibria.

Methanol and ethanol are no more acidic than water itself and are so

slightly dissociated in water that requir aqueous solution are neutral (pH 7).

The anion of an alcohol, RO-, known as an alkoxide ion, is a strong base, as

expected for the anion of a weak acid.

Alkoxides are prepared by reaction of an alcohol with an alkali metal, for

example:


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Acidity of Alcohols and Phenols

Phenols are considerably more acidic than water. Phenol itself (Ka = 1x10-10),

for example, is close to HCN (Ka = 6x10-10) and HCO3- (Ka = 5x10-11) in acidity.

Phenols react as weak Bronsted-Lowry acids with hydroxide ion and are

soluble in dilute aqueous sodium hydroxide.


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Names and Properties of Ethers

Ethers with simple alkyl or aryl groups are named just by identifying the

two groups bonded to oxygen and adding the word ether

If both groups are the same, thedi- is often left out and we refer to

methyl ether or ethyl ether.

A reference to just ether usually means diethyl ether.

Compounds containing the COC group in a ring are classified as cyclic

ethers but are not named as such.


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Names and Properties of Ethers

The RO group is reffered to as an alkoxy group; CH3O is a methoxy,

CH3CH2O is an ethoxygroup, and so on. These names are used when the ether functional group is present with

other functional groups, for example:

Though polar, ethers lack the hydroxyl group of water and alcohols, and

ether molecules do not hydrogen-bond to each other.

Thus, the simple ethers are higher boiling point han comparable alkanes

but lower boiling than alcohols.

The ether oxygen can hydrogen-bond with water, causing dimethyl ether

to be water-soluble and diethyl ether to be partially miscible with water.

Higher ethers are not only slightly soluble or insoluble in water. Ether are

good solvent for most organic molecules.


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Some Common Ethers

Inhalation anesthetics

Enflurane (trade name Enflurane) and

isoflurane (trade name Forane) are

widely used nonflamable, nonexplosive

anesthetics that produce a rapid

anesthesia from which recovery is alsorapid.

They are both low-boiling liquids

administered as vapors (enflurane, bp

56.5rC; isoflurane, bp 48.5rC).


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Some Common Ethers

Ethers exist throuhout the plant and animal kingdoms.

Sme are present in essential oil and are used in perfumes; other have avariety of biological roles.

The threemembered epoxide ring in juvenile hormone is quite reactive

because the oxygen and carbon bond angles are highly strained in the

small ring.

Some biomolecules containing ether groups


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Sulfur-containing Compounds: Thiols and Disulfides

Thiols is the elements just below oxygen in the periodic table, and many

oxygen-containing compounds have sulfur analogs. Thiols (RSH), also called mercaptans, are sulfur analogs of alcohols.

Mercaptan is an alternate name for a thiol, (RSH).

The systematics parent name of a thiol is formed by adding thiol to the

parent hydrocarbon name.

Otherwise, thiols are named in the same way as alcohols.


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The most outstanding characteristic of thiols is their appaling odor. Thiol react with mild oxidizing agents to yield disulfide, RSSR.

Two thiols joint together in this reaction, the hydrogen from each is lost,

and then the two sulfurs bond together.



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The easy formation of SS bond between cystein groups help to pull

large protein molecules into the shapes they need to function.

Hair protein, for exanple, is unusually rich in SH groups.

When hair ispermed , a mild oxidizing agent causes disulfide bonds to

form between SH groups, resulting in the introduction of bends and kinks

into the hair.

Sulfur bridges in hair. Chemistry can give you curly hair. A permanent wave

results when disulfide bridges are formed between SH groups in hair protein

molecules.


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Halogen-containing Compounds

Halogen-containing organic compounds result from the replacement of

hydrogen atoms by halogen atoms

The alkyl halide, RX, where R is an alkyl group and X is halogen. Their common names are formed by giving the name of the alkyl group

followd by the alogen name with an-ide ending.

Systematic name for alkyl halides are derived like those of other families

of compounds, by identifying the hydrocarbon root, using the alkane

ending-ane, numbering the halogen substituens, and naming them as

fluoro-, chloro-, bromo-, or iodo- groups.


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Some Halogen-containing Compounds

An iodine-containing hormone secreated by the thyroid gland.

A deficiency of iodine in the human diet leads to a low thyroxine level,which causes a condition called goiter and a resulting swelling of the

thyroid gland.


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Some Halogen-containing Compounds

Agricultural use of herbicides such as 2,4-D and fungiside such as Captan

has resulted in vastly increased crop yield and also chlorinated pesticide

of DDT is responsible for the control of malaria and thypus

But, chlorinated pesticide present problems becausr they are not broken

down by natural processes and persist in the environment.

They remain in the fatty tissues of organism and accumulate up the food

chain as larger organism consume smaller one.

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