1PreDP: Organic chemistry

Teacher: Annika Nyberg

annika.nyberg@mattliden.fi

Content:

1. Introduction2. Hydrocarbons3. Functional groups4. Alcohols and phenols5. Aldehydes 6. Ketones 7. Carboxylic acids, Acid -base reactions8. Esters, Fats9. Amines, Proteins10. Carbohydrates11. Dilution of solutions

Revision

EXAM

1. Introduction

1.1 Carbon is a unique element

Lewis structure of carbon:

Carbon atoms can form long chains that are linked by single, double and/ortriple bonds

Carbon and hydrogen are the basic building blocks in organic compounds.

Other elements can be present in organic compounds as well, such as oxygen, nitrogen, phosphorus, halogens (F, Cl, Br, I) or sulfur.

1.2 Organic compounds

Every living organism is made of organic compounds and the organic compounds are all around you:

21.3 Crude oil

Crude oil was formed over millions of years ago when the remains of animals and plants were trapped under layers of rock.

Crude oil is a complex mixture of many different organic compounds, mainly alkanes.

1.4 The carbon cycle

1.5 Refining

In an oil refinery the alkanes are separated (according to boiling point) by fractional distillation.

The various fractions, with different physical characteristics, are used in a wide variety of circumstances, mainly as fuels.

32. Hydrocarbons

There are at least 6 million different organic compounds, all with their own physical and chemical properties.

In order to study all these organic compounds, they are categorized into ”families” according to their structures.

Members of these families have similar chemical reactivities.

Hydrocarbon:

Chained hydrocarbons (straight-chain):

Chained hydrocarbons (branched chain):

Cyclic hydrocarbons:

2.1 Ways to describe organic compounds

Empirical formula:

Molecular formula:

Structural formula:

a) Full structure:

b) Condensed structure:

c) Skeletal (line-bond) structure:

d) Molecular model:

4General rules for skeletal structures (line-bond structures):

- Each point on a jagged line is assumed to be a carbon atom.

- The ends on lines are assumed to be carbon atoms.

- All hydrogens attached to non-carbon elements (like N, O, S) must be explicitly shown.

- All atoms are presumed to be neutral unless a charge is specifically shown.

a) Draw the condensed structure and the skeletal structure for 2-methylbutane.

b) Convert the skeletal structures below into full structures AND to molecular formulas.

2.2 Isomers

Draw

a) the three different structures of C5H12

b) the five different structures of C6H14

c) the structures of three isomers of C8H18

52.3 Alkanes

Saturated:

Reactivity:

Combustion:

Ex. Give a balanced equation for the combustion reaction of gasoline (C4H10) in excess oxygen.

Complete the table below.

Name Molecular formula

Full structure State (at room temperature)

Methane CH4 Gas

Gas

Propane

Gas

C5H12 Liquid

Heptane Liquid

C9H20

Decane Liquid

2.4 Alkenes

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Unsaturated (double bond/bonds). The double bond reacts in addition reactions.

Addition reactions:

a) Alkanes + water

b) Alkanes + halogens (= alkene test)

c) Polyethene

2.5 Alkynes

2.6 Aromatic hydrocarbons

2.7 Halogenated hydrocarbons

2.8 Naming hydrocarbons

7What is the name of the molecule?

The systematic name of an alkane is obtained using the following rules:

1. Determine the number of carbons in the longest continuous carbon chain. This chain is called the parent hydrocarbon.

Number of C Parent

2. The functional group is described by a ending (or suffix) to the name.

Single bond:

Double bond:

Triple bond:

3. The name of any alkyl substituent (= the branches) is cited before the name of the parent hydrocarbon.

- Indicate the position with a number.

- Give the substituent as low a number as possible.

Alkyl group Name

4. If more than one substituent is attached to the parent hydrocarbon, the chain is numbered in the direction that will result in the lowest possible number in the name of the compound.

5. If a compound contains two or more identical substitutes, the prefixes “di,” “tri,” and “tetra” are used.

Prefix - Parent - Suffix

Ex 1. Name the following molecules

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Ex 2. Draw the following molecules

a) 3-methylhexane

b) hex-2-ene

c) hex-3-yne

d) 4-methyl-pent-2-ene

Ex 3. Draw structural formulas (full and condensed structures) for the following substances:

a) 2-methylheptane

b) 4-ethyl-2-methylhexane

c) 2,4,4-trimethylheptane

d) 1,1-dimethylcyclopentane

Ex 4. Propose structures for molecules that fit the following descriptions:

a) an alkene with six carbons

b) a cycloalkane with five carbons

c) an alkene, C7H14

e) a cycloalkane, C3H4

9Ex 5. Which of the structures in each of the following sets represent the same compound and which represent different compounds?

Ex 6. Give IUPAC names for the following alkanes

Extension: Name the following molecules

103. FUNCTIONAL GROUPS

Ex 7. Identify the organic compound that is an

a) alcohol b) amine c) aldehyde

Ex 8. Identify the functional groups in the LSD molecule.

Ex 9. Identify and name the functional groups in the heroine molecule.

11Homologous series

Full structural formula Condensed structural formula

Skeletal structural formula

Molecular formula

Empirical formula

Functional group

Suffix for IUPAC name

Alkane

Ex. butaneAlkene

Ex. butene

Alkyne

Ex. butyne

Aromatic compound

Ex. benzeneHalogeno-alkanes

Ex.

1-chlorobutane

12Homologous series

Full structural formula Condensed structural formula

Skeletal structural formula

Molecular formula

Empirical formula

Functional group

Suffix for IUPAC name

Alcohol

Ex. butanolAldehyde

Ex. butanalKetone

Ex. butanone

Carboxylic acid

Ex. butanoic acid

Esters

Ex. ethylbutanoateAmine

Ex. butylamine

=aminobutane

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Ex 10. Circle in and name the functional groups in each molecule.

Ex 11. Classify each substance according to their functional group.

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Ex 12. Draw the skeletal structure of vitamin A and identify the functional groups.

Ex 13*. Draw structures for compounds that have the following molecular formulas.

C2H7N C3H6O C4H9Cl

Ex 14*. Draw the structural formula of an organic compound that contains 8 carbon atoms and the following functional groups: ketone, amine or ester. What is the molecular formula of your compound?

4. ALCOHOLS AND PHENOLS

4.1 Alcohols

a) Glycol and glycerol

b) Methanol

c) Ethanol

d) Menthol and cholesterol

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4.2 Phenols

4.3 Naming

• Alcohols are also classified as primary, secondary or tertiary, depending on the location of the hydroxyl-group.

Ex 15. Name the following molecules.

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4.4 Combustion

Ex 16. Write the balanced equation for the combustion of ethanol.

4.5 Oxidation of alcohols

Ex 17. Show, using structural formulas, the following oxidation reactions:

a) oxidation of methanol to methanal b) oxidation of 2-propanol to propanonec) oxidation of cyclohexanol to cyclohexanone

Ex 18. Draw the structural formulas for the following molecules:

a) propan-2-ol

b) 4-methylphenol (para-cresol)

c) 1,2,3,4,5-pentahydroxypentane (xylitol)Ex 19. What mass of glucose must be fermented to give 5.oo kg of ethanol?

a) Calculate the amount of ethanol in moles (nethanol)

17b) Calculate the amount of glucose in moles .

c) Calculate the mass of glucose.

4.6 Mass percent

Ex 20. Calculate the mass-% of sugar in a solution that contains 50 grams sugar in 210 grams of water.

Ex 21. Calculate the mass-% of salt in sea water, if there is 32 grams of salt for every 1ooo grams of sea water.

4.7 Volume percent

Ex 22. Calculate the volume of pure ethanol in a bottle of wine (750 ml) with a 12 volume-% of ethanol.

Ex 23. Calculate the volume of pure acetic acid in a diluted vinegar solution with 10 percent of acetic acid by volume.

4.8 Concentration

Ex 24. 50,0 g of sugar, C12H22O11, is dissolved in water so that the final volume of the solution is 250 ml. Calculate the concentration of the solution.

5. ALDEHYDES

Aldehydes from alcohols

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a) Formaldehyde b) Vanillin

c) Anisaldehyde

6. KETONES

Ex 25. Name the following molecules:

Ex 26. Draw the structural formulas for the following molecules:

a) propanal

b) 2,3-butadione (buttery flavor)

c) 3-fenyl-2-propenal (cinnamaldehyde, gives cinnamon its flavor)

Ex 27. Show, using structural formulas, an oxidation reaction of an aldehyde to a carboxylic acid.

7. CARBOXYLIC ACIDS

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a) ethanoic acid b) butanoic acid

c) hexanoic acid

7.1 Condensation

Carboxylic acids react with alcohols to form esters:

7.2. Acid-base reactions

An acid donates protons (H+) to a base that accepts protons in a chemical reaction.

A base must have an extra non-bonded electron pair that it can share with the proton.

An aqueous solution becomes acidic when an acid donates a proton to a water molecule, because an oxonium ion (H3O+) is produced.

Ex 28. Draw, with structural formulas:

a) the reaction of methanoic acid and water

b) the formation of the ester methyl salicylate (“oil of wintergreen”) from salicylic acid and methanol

c) the formation of the ester methyl butanoate from methanol and butanoic acid

8. ESTERS AND FATS

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8.1 Fats

Fats and oils are large esters, as they form when glycerol and three fatty acids (= carboxylic acids with long carbon chains containing an even number of carbon atoms between 12 and 20) undergo condensation reaction:

The three fatty acids need not be the same. A given fat or oil is usually a complex mixture of esters of different fatty acids.

Saturated fats:

Palmitic acid:

Unsaturated fats:

Oleic acid:

9. AMINES

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Amines are derivatives of ammonia, where 1, 2 or 3 hydrogens have been displaced by carbon chains.

Amines are classified as primary, secondary or tertiary.

Ex 29. State whether the following amines are primary, secondary or tertiary.

9.1 The neutralization reaction of amines with acids

The fishy odour of di- and trimethylamines disappears if they are neutralized with citric acid or ethanoic acid.

9.2 Amino acids

Amino acids contain two functional groups: a basic amino group and an acidic carboxyl group.

9.3 Peptide bond

9.4 PROTEINS

22 All proteins are made up of many amino acids linked together into a long chain (more than 50 amino acids).

The sequence in which amino acids are bonded together determine only the primary protein structure.

The large molecule then folds and bonds with other protein molecules to form the final protein.

9.5 Protein denaturation

A small change in temperature or pH will disrupt the tertiary structure (the weak intermolecular bonds between the chains) and cause the protein to become denatured.

The primary structure remains intact (the covalent bonds are not affected), but the protein unfolds from its well defined shape to a randomly shape.

Ex 30. a) Name the following compounds:

b) Draw the formation of a peptide bond between the amino acids glycine

and alanine to form glycylalanine:

10. CARBOHYDRATES

23 Every living organism contains carbohydrates:- Sugar and starch in food- Cellulose in wood, paper and cotton- Carbohydrates are synthesized by green plants during photosynthesis.

Carbohydrates are our main source of energy. The larger the molecule, the longer it takes for our bodies to

break it down. Most of the simple carbohydrates taste sweet.

10.1 Monosaccharides

10.2 Disaccharides

Two monosaccharides linked together. Sucrose (table sugar) is a disaccharide made up of one glucose

molecule linked to one fructose molecule.

10.3 Polysaccharides

Cellulose is a polysaccharide made up of several thousand glucose molecules linked together.

11. Dilution of solutions

Ex 31. If 25,0 ml of 0,56 M H2SO4 is diluted to a volume of 125 ml, what is the molarity of the resulting solution?

Ex 32. To what volume must 50,0 ml of 1,50 M HCl be diluted to produce 0,200 M HCl?

Ex 33. How would you prepare 1,00 dm3 of a 0,50 M solution of H2SO4 from concentrated (18 M) sulfuric acid?

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