ORGANIC CHEMISTRY Chapter 25

Vacation packet #2

Mrs. Brunet

Our extent of Organic Chemistry for the AP test is pretty limited…yeah! As part of the

Descriptive Chemistry, you need to know: “3. Introduction to organic chemistry: hydrocarbons and

functional groups (structure, nomenclature, chemical properties)”

Organic Chemistry is the study of carbon containing compounds.

Before 1828 the vital force theory, which stated that organic

compounds could be extracted only from living, or once living

organisms, was widely accepted. Only to be dashed by Friedrich

Wohler’s synthesis of urea (not urine but a component of it), an

organic compound from the heating of an organic compound from

the heating of an inorganic compound. Check out the organic

chemist’s version of our favorite periodic table

Carbon exists as an element in three different forms, called

allotropes: graphite, pencil “leads”; diamond, a girl’s best friend; and

buckministerfullerene, or the bucky ball (looks like a hollow soccer

ball). [25.1]

The basics of our expected o-chem knowledge for the AP exam

(chemmy bear link = study cards):

http://www.chemmybear.com/apch23sc.pdf

Nomenclature

Functional groups

Properties of compounds

How to draw various types of isomers

Nomenclature of organic compounds is based upon the structure of

the molecule

Straight chain of carbons (normal or n-)

Branched chains

Cyclic molecules, rings like benzene

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

Let’s start with the basics and we will build on those. I know this stuff looks big and bad but

it’s really quite simple…honest engine. Don’t be fooled by the IUPAC logo, it just stands for

International Union of Pure and Applied Chemistry. I suggest you make your own clever

acronym for this stuff. Check out section 25.2-25.3, your book has a good plan for naming

hydrocarbons.

First of all the basis of the names is on the number of carbon atoms that make up the

structure. The last name consists of one of the following roots:

# of

carbons

in the

longest

chain

Root

1 Meth-

2 Eth-

3 Prop-

4 But-

5 Pent-

6 Hex-

7 Hept-

8 Oct-

9 Non-

10 Dec-

Second is the suffix of the last name and that depends upon the type of bonds between the

carbons.

One of more of

these types

Suffix of

name

All single bonds -ane

At least one double

bond

-ene

At least one triple

bond

-yne

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

Let’s start with alkanes which are single (sigma,

this is a little ahead for us but every single

covalent bond is called a sigma bond) bonded

molecules. These have the general formula CnH2n+2.

Alkanes containing fewer than 5 carbons are gases

(propane, the outdoor barbeque fuel) 5-15 are

liquids (like kerosene and gasoline), and >16 are

solids (paraffin or wax). Alkanes are said to be

saturated because they have all single bonds.

This molecule can be drawn structurally (above) or

made with 3D models or written condensed: CH3CH3 This is ethane because there are two

carbons in the longest chain and only single bonding.

Many times hydrogens are omitted to make the structural formula simpler, or condensed. This

can be useful when the longer chains are being used:

C—C—C—C also written as CH3CH2CH2CH3 or where each end represents a carbon

Four carbons in a straight chain, this is n-butane. The n stands for normal or straight chain.

The name here changes even though there are still four carbons. Branched hydrocarbons

(hydrogen and carbon compounds) are named based upon the longest chain. Anyway, you look at

this molecule it has three continuous carbons thus propane. But we must name the branched

part. Since the branched part is one carbon atom, the name still comes from the prefixes,

meth-, but we substitute the suffix –yl and add it to the beginning of the name for the longest

chain METHYL PROPANE or more commonly, isobutane.

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

For the longer chains the placement of the side group is denoted by numbering. The longest

carbon chain is numbered with the lowest numbering associated with the side groups.

The name for this molecule is 2-methylpentane. The other option 4-methylpentane would be

incorrect because 2 is a lower value. The longest chain is five and all single bonds with a side

group off of the second carbon.

The rules for naming alkanes are condensed in a table on pg. 1068 and good examples on pg.

1069. Look at exercises 25.1 on pg. 1071, and 25.2 on pg. 1072. Check out a few more examples

at http://www.sciencegeek.net/APchemistry/APtaters/alkanes.htm

You should now be ready to do homework #1 (in dropbox).

CYCLOALKANES

Arranged in a cyclic pattern, these occur with the general formula of CnH2n The names use the

same parent name, adding the prefix “cyclo” to describe the shapes. For naming rules and

practice see science geek.com: http://www.sciencegeek.net/APchemistry/APtat

ers/cycloalkanes.htm

UNSATURATED HYDROCARBONS

http://www.organicchemistry.com/tag/unsaturated-carbon/

ALKENES [25.4]

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

-unsaturated hydrocarbons occurring in CnH2n but are not cyclic. These are said to be

unsaturated because the double bond can open up and become saturated with more hydrogen or

other substituents.

-naming:

Use longest chain containing a double

bond, can by cyclic also

2-Butene

IUPAC name

Use the lowest number for the first

double-bonded carbon

Suffix of hydrocarbon changes to –

ene to represent the double bond

Ethene (ethylene)

o Over 10 million tons/year

produced

o Used in refining of petroleum

Also for production of plastics,

antifreeze, synthetic fibers, and

solvents

Ethylene

IUPAC name[hide]

Ethene

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

Propene (propylene) PPE

o Plastics and synthetic fibers

Propene

IUPAC name[hide]

Propene

ALKYNES more from science geek:

http://www.sciencegeek.net/APchemistry/or

ganic/alkene_alkyne.shtml

General formula of CnH2n-2 , very

reactive, unsaturated

Contains at least one triple bond

Suffix changes to –yne

*Note: If there are two or more triple

bonds, they are called alkadiynes (two triple

bonds), alkatriynes (three triple bonds), and

so on, NOT alkynes. This also applies to the

alkenes.

HW 2 p. 1110 #6,8,12,22,24

AROMATIC HYDROCARBONS

http://chemistry.boisestate.edu/people/rich

ardbanks/organic/nomenclature/aromaticno

menclature1.htm

Benzene

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

IUPAC name[hide]

Benzene

Cyclic and unsaturated

C6H6 is the most simple, benzene

Aromatic compounds are generally

derived from benzene

Most have distinctive odors, but not

all

Used in plastics, fibers, explosives,

paint, and petroleum

FUNCTIONAL GROUPS p1083

HALOGEN DERIVATIVES

Compound has a halogen atom(s) substituted for a hydrogen atom(s)

Halogen names are treated like prefixes to the parent name

F=fluoro-; Cl=cloro-; Br=bromo-; I=iodo-

Chloroform

IUPAC name[hide]

Chloroform

Systematic name[hide]

Trichloromethane

Other names[hide]

Formyl trichloride, Methane trichloride, Methyl trichloride,

Methenyl trichloride, TCM, Freon 20, R-20, UN 1888

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

HALOHYDROCARBONS (sounds like a video game, huh?)

Replacement of hydrogen in a hydrocarbon with one or more halogens

Nomenclature follows rules of previous sections

ALCOHOLS 1,2-ethanediol or antifreeze

An hydroxyl (-OH) is attached to the end of the hydrocarbon or R

For naming, drop –e parent hydrocarbon with –d

Number placement of hydroxyl group with smallest possible

Alcohols can be primary, secondary, or tertiary

The lower molecular mass alcohols are soluble in water through hydrogen bonding with the

water. Alcohols with four or more carbon atoms however, have such a large nonpolar part of the

molecule that they are not soluble in water, a polar solvent.

ETHERS

Organic oxides with –O- within the body of the molecule

Nomenclature follows basic hydrocarbon rules for both sides of R-O-R, followed by the

second name, ether.

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

dimethyl ether

ALDEHYDES

Contain a carbonyl group bonded to at least one hydrogen atom

Nomenclature drops final –e and adds –al and a number indicating the position of the

carbonyl group, where necessary. (aldehyde carbon is always #1)

Aldehydes have strong odors; two of the best are vanillin (left) and cinnamadlehyde

KETONES

Carbonyl group BUT bonded to two carbon atoms, in the middle

Nomenclature drops the final –e then adds –one

Number the placement of the carbonyl group

Ketones are used as solvents, you use this one on the white boards all the time!

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

CARBOXYLIC ACIDS

Carboxyl is from “carbonyl” and “hydroxyl”

Naming: drop –e then add –ioc acid

Weak acids, such as acetic acid, the active ingredient in vinegar

Formic acid (or methanoic acid) is the agent that causes pain from an ant bite

ESTERS

Often have sweet, fruity odors

Esters are formed from an alcohol and an organic acid

Naming: the names of the alcohol is first, dropping the –ol and adding –yl, next the

name of the acid drops –oic and adds –ate

Some esters are used as substitutes for natural products and enhancers in food.

Remember the first lab? You were to identify the ester; some of you smelled octyl

acetate, orange aroma; or ethyl butyrate, pineapple aroma. Other fun ones: methyl

butyrate, apple; isopentyl acetate, banana; pentyl propionate, apricot; isobutyl

formate, raspberry, benzyl acetate, jasmine

Are you a fan of grapples? You can make your own with regular apples and grape ester

found in grape koolaid. http://www.ehow.com/how_5907945_make-grapple-apple.html

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

Wintergreen lifesavers have wintergreen oil and can produce a visible spark when

cracked. Live a little…try it! http://www.ehow.com/how_2097426_make-light-spark-

lifesaver.html

AMINES

Amines are related to ammonia, NH3…you remember

ammonia? A friend of the gravimetric plant food lab

Starting with NH3 replacing one H with a carbon chain

(primary); two H’s (secondary); or three H’s (tertiary).

This makes an amine.

Amines are organic versions of bases

Amines are responsible for unpleasant odors like decaying

tissue, old fish

Aromatic amines (carcinogens) are used to make dyes. Be

careful!

Complex molecules use amino- for the -NH2 functional group

HW 3 p. 111-2 #40,46,52

TYPES OF ORGANIC REACTIONS:

1] Substitution: replacing of one functional group by another

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

2] Addition: it is common for alkenes to break one bond and gain two substituents.

3] Elimination: one product is removed, leaving an unsaturated hydrocarbon, also is called

dehydration

4] Esterification: an alcohol reacts with an organic acid to make an ester

5] Saponification: esters are split into alcohols and salts of carboxylic acids; triglycerides can

be treated with aqueous sodium hydroxide to form glycerol and soaps.

HW 4 p. 1111 #32

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

ISOMERS

Two organic compounds may have formulas with exactly the same

atoms but different properties. These compounds are called isomers,

there are three types: structural isomers, cis- and trans- isomers,

stereoisomers.

Structural Isomers: Butane and allother alkanes exhibit structural isomerism. For

example, butane can exist as a straight chain or n-butane (normal butane). The

branched isomer of butane is called isobutene:

Isomers can be difficult to figure and draw, just remember to count the longest continuous

chain. This can often show that some may appear as isomers but really are the same

arrangement. With alkenes and alkynes, try moving the multiple bond around to different

locations because multiple bonds are rigid.

Isomers are discussed all throughout the organic chemistry tutorial by science geek.com

http://www.sciencegeek.net/APchemistry/organic/ochem.shtml

Cis- and Trans- Isomers: These isomers refer to molecules that contain atoms or groups of

atoms in different positions around a rigid ring (rigid = contains multiple bonds) or bond.

Cis- means “on the same side”; Trans- means “on

opposite sides” and refers to groups attached to

double-bonded carbon atoms. The double bond is

the key to the distinctly different molecules which

have different chemical and physical properties as a

result of their structures.

Stereoisomers or Optical Isomerism: These isomers are

the hardest to recognize and take considerable brain power

and spatial thinking to work with; they have the same

formulas, and every atom is bonded to the same atom.

These are not structural isomers, but they are not exactly

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

the same. I have to actually make models to get this and fortunately

we are born with two perfect stereoisomers. Left hand meet right

hand. (or feet) They are the same in every way, yet they are not

identical. They are mirror images of each other and that, girls and

boys, is a stereoisomer!

Stereoisomers, unlike cis- and trans- isomers, have identical physical properties such as

melting and boiling points. The chemical reactivity of two stereoisomers is, for the most

part, identical also. However, stereoisomers often have different chemical reactivites in

biological systems (like us) where the overall shape of the molecule is important. Most amino

acids have two stereoisomers. In all known living matter the stereoisomers are those that

rotate light to the left. Yet synthetic production of pharmaceuticals produces 50:50 right

and left isomers, even when only one is effective as a drug. Production of only one of the

isomers is possible but very expensive….sound familiar when considering prescription

medication?

HW 5: AP Problems

2002 B

Consider the hydrocarbon pentane, C5H12 (molar mass 72.15 g).

(a) Write the balanced equation for the combustion of pentane to yield carbon dioxide and water.

(b) What volume of dry carbon dioxide, measured at 25˚C and 785 mm Hg, will result from the complete

combustion of 2.50 g of pentane?

(c) The complete combustion of 5.00 g of pentane releases 243 kJ of heat. On the basis of this information,

calculate the value of ∆H for the complete combustion of one mole of pentane.

(d) Under identical conditions, a sample of an unknown gas effuses into a vacuum at twice the rate that a

sample of pentane gas effuses. Calculate the molar mass of the unknown gas.

(e) The structural formula of one isomer of pentane is shown below. Draw the structural formulas for the other

two isomers of pentane. Be sure to include all atoms of hydrogen and carbon in your structures.

ORGANIC CHEMISTRY Chapter 25

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Mrs. Brunet

2003 D

Compound

Name

Compound

Formula

∆H˚vap

(kJ mol-1

)

Propane CH3CH2CH3 19.0

Propanone CH3COCH3 32.0

1-propanol CH3CH2CH2OH 47.3

Using the information in the table above, answer the following questions about organic compounds.

(a) For propanone, draw the complete structural formula (showing all atoms and bonds);

(b) For each pair of compounds below, explain why they do not have the same value for their standard heat of

vaporization, ∆H˚vap. (You must include specific information about both compounds in each pair.)

(i) Propane and propanone

(ii) Propanone and 1-propanol

(c) Draw the complete structural formula for an isomer of the molecule you drew in, part (a) (i).

Testing Review

Naming alkanes: http://www.sciencegeek.net/APchemistry/APtaters/chap22alkanes.htm

Naming Chemical Compounds PowerPoint is good review up until slide 27 where the organic

chemistry starts! I found this on the internet and lost the citing information…oops.