1. Alkanes and Cycloalkanes - PowerPoint Presentation

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1. Alkanes and Cycloalkanes

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Alkanes and CycloalkanesHydrocarbons (contain only carbon and hydrogen)

Saturated:

(Contain only single bonds) Alkanes (CnH2N + 2 ) Cycloalkanes (CnH2N )b) Unsaturated: contain Alkenes: double bonds (,,,CnH2N) Alkynes: triple bonds ((CnH2N - 2)Aromatic: benzene like compounds

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The structure of alkanes

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Cycloalkanes:

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Some applications of hydrocarbons in health field5Slide6

Halothane

(

trademarked as Fluothane)Is an inhalational general anesthetic. Its IUPAC name is 2-bromo-2-chloro-1,1,1-trifluoroethane. It is the only inhalational anesthetic agent containing a bromine atom. It is colorless and pleasant-smelling, but unstable in light.Side effects:Repeated exposure to halothane in adults was noted in rare cases to result in severe liver injury

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Chloral hydrate

Chloral hydrate induces sleep and prevent convulsions. Used for cattle, horses and poultry

2,2,2- trichloroethane-1, 1- diol7Slide8

Other widely used haloalkanes

Ethyl chloride used as a local anesthetic

CH3-CH2-ClFreon-12: Used in aerosol containers (as a refrigerator) CCl2F2 Dichlorodifluoromethane8Slide9

Alcohols, Thiols, Phenols, Ether9Slide10

The general formula of alcohols is R-OHWhere

R

indicates the Alkyl group attached to an –OHR could be: CH3, CH3CH2- CH3CH2CH2-, ect.,

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Alcohols are soluble in H2O because of the –OH

group.

But as the length of the carbon chain increases, the solubility decreasesAlcohols react with acids to give compounds called esters: 11Slide12

USES OF ALCOHOLS

1.

Methyl alcohol (methanol) CH3OHCommonly Known as wood alcoholThe U.S. production of methanol is 1.4 billion gallons per year. Most of it is used to produce formaldehyde and other chemicals,Is also used as an anti-freeze.Used as a solvent in many industrial reactions.12Slide13

It should never be applied to the body neither should the vapors be inhaled because it can be absorbed both through the skin and through the respiratory tract.Ingestion as little as 15 ml can cause blindness (it is oxidized to formaldehyde

(CH

2=O), which binds to opsin, preventing formation of rhodopsin, the light-sensitive pigment needed for vision.While 30 ml are enough to cause death.13Slide14

Types of Alcohols1. Primary alcohols

2. Secondary alcohols

3. Tertiary alcohols14Slide15

Reactions of Alcohols1. Dehydration of alcohols:

Alcohols can be dehydrated by heating them with a strong acid.

For example, When ethanol is heated at 180°C with a small amount of concentrated sulfuric acid, a good yield of ethylene is obtained.15Slide16

2. Formation of Ethers16Slide17

3. Oxidation:Primary alcohols can be oxidized to form aldehyde,Further oxidation of

aldehyde

yields an acid.17Slide18

Secondary Alcohols can be oxidized to give ketones

Tertiary alcohols

, having no hydrogen atom on the hydroxyl-bearing carbon, do not undergo this type of oxidation18Slide19

4. Forming esters:Alcohols react with organic acids to give esters. 19Slide20

2. ThiolsAre sulfur analogs of alcohols and contain an

-SH

functional group in place of an –OH group 20Slide21

Properties of thiolsMany thiols

are found in nature.

They have unpleasant odor.Onion when cut, releases 1-propanethiol HS-CH2-CH2-CH3The odor of garlic is due to thiols.Skunk when attacked it releases thiols.Thiols added to heating - & cooking- gas to detect gas leak. 21Slide22

3. PhenolsWhen –OH is attached to benzene ring, phenol is formed.

Unlike alcohols, phenols are weak acids

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Phenols react with aqueous solution of sodium hydroxide to form a soluble salt: Uses of Phenols:1. As antiseptic

2. As disinfectant

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4. ethersAll ethers are compounds in which two organic groups are connected to a single oxygen atom.

The general formula for an ether is

R-O-R’where R and R’ may be identical or different, and they may be alkyl or aryl groups. In the common anesthetic, both R and R’ are ethyl groups. CH3CH2-O-CH2CH324Slide25

Properties of ethersLow boiling pointThey are good solvents because they do not react with solutions.

Ethyl ether is used to extract organic materials from naturally occurring substances.

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Ether as anestheticUsed as a general anestheticAdvantages:

Easy to administer

Excellent muscular relaxantLittle effect on respiration, blood pressure26Slide27

Disadvantage:Very flammableIrritating to membrane of respiratory tract

Today ether as anesthetic has been replaced by:

HalothaneNitrous oxideEnflurane 27Slide28

Aldehydes,

Ketones

, Carboxylic Acids, And Amines28Slide29

Aldehydes

Aldehydes

are characterized by the presence of the carbonyl group COAldehydes have at least one hydrogen atom attached to the carbonyl carbon atom. The remaining group may be another hydrogen atom or any aliphatic or aromatic organic group.29Slide30

Uses of Aldehydes

1. Formalin is used as a disinfectant and preservative (used to preserve biologic specimens).

2. Formaldehyde is mostly used in the manufacture of plastics, building insulation. 3. Fumes of formaldehyde solutions are very irritating, so should not be used directly on a patient skin30Slide31

4. Glutaraldehyde

is used as a good sterilizing agent. 5. Paraldehyde is used as a hypnotic. Is formed by polymerization of 3 molecules of acetaldehydes 6. Glyceraldehyde is an important in carbohydrate metabolism31Slide32

Ketones

The general structural formula for

ketones:R-CO-RPreparation:By oxidation of secondary alcohols:32Slide33

Uses of ketones

1. Acetone is a good solvent for fats and oils

2. Acetone is used in fingernail polish and polish removal3. Acetone is normally present in small amounts in blood & urine. But in diabetes mellitus it is present in higher concentration.4. Dihydroxyacetone is an intermediate in carbohydrate metabolism HO-CH2-CO-CH2OH33Slide34

Hemiacetals

and

hemiketals1. Reaction of an aldehyde with an alcohol yields compounds known as Hemiacetals

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2. Reactions of a ketone with an alcohol yields compounds known as

Hemiketals

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If a hemiacetal or a hemiketal

reacts with a second alcohol, an acetal or ketal respectively is formed. + R”’-OH R’-C-OR”’36RO

C

R’

OH

R’’

OR

R”

KetalSlide37

The Hemiacetals/Acetals &

Hemiketal

/Ketals are important in understanding the structures of monosaccharides37Slide38

Carboxylic AcidsFunctional group is (-COOH)

Preparation by oxidation of an

aldehyde: H OH R-C=O + [ O ] R-C=O CH3-CHO + [O] CH3-CO-OH acetic acid38

AcidSlide39

Oxidation CH3-OH yields CH2=O

Oxidation of

aldehyde yields carbooxylic acid (HCOOH; formic acid)Formic acid is also named as methanoic acid CH3CH2-OH CH3COOH Ethanol acetic acid39[O]Slide40

Properties & Reactions of Organic Acids

1. Most organic acids are relatively weak acids, since they dissociate only slightly in water:

CH3COOH H+ + CH3COO-2. Organic acids react with bases to form salts and water: RCOOH + NaOH RCOONa + H2O CH3COOH + NaOH CH3

COONa + H

2

O

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3. They react with bicarbonates and carbonates: CH3

COOH + NaHCO

3 CH3COONa+CO2(g) + H2O 2 HCOOH + NaCO3 2HCOONa + CO2(g) + H2O4. Organic acids with few carbon atoms are soluble in water. As the length of the carbon chain increases, the solubility in water decreases.41Slide42

5. Organic acid react with alcohols to form esters.

RCOOH + R-OH R-CO-OR + H2O42Slide43

Medically Important Organic Acids

1. Formic acid

HCOOH is formed in bees sting & ants, and causes the characteristic pain and swelling when it is injected into tissues.2. Acetic acid, CH3COOH found in vinegar in 4 to 5 % solution.

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3. Citric acid

Found in citrus fruits

- Magnesium citrate, a salt of citric acid Is used as a cathartic to stimulate evacuation of bowels- Sodium citrate, used as a blood anticoagulant (it removes Ca2+ needed for coagulation from the blood)44Slide45

4. Lactic Acid

CH

3-CH(OH)-COOHFound in sour milk.It is formed whenever the body produces energy anaerobically5. Oxalic acid HOOC-COOHA strong naturally occurring acidUsed to remove stains from clothingIt is poisonous when taken internally45Slide46

Oxalate salts prevent clotting by chelating Ca2+From blood (however it should not be applied directly on the blood due to it’s toxicity)

6.

Pyruvic acidProduced during glycolysis.In muscle pyruvate is reduced to lactic acid during anaerobic exerciseIn tissues pyruvate is converted to acetyl-Coenzyme A, which enters the Krebs cycle.46Slide47

7. Tartaric acid

It is both an acid & alcohol HOOC-CH-CH-COOH OH OH 2, 3-dihydroxysuccinic acid Found in several fruits such as grapes and bananas Potassium hydrogen tartarate is used in making baking powder. Rochelle salt or potassium sodium tartarate used as a mild cathartic.47Slide48

8.

Stearic

acid: - Is a fatty acid, insoluble in water C17H35COOH

- Is a solid greasy like acid

Sodium

stearate

is the commonly used soap

C

17

H

35

COOH +

NaOH

C

17

H

35

COONa

+ H

2

O

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