Organic Chemistry 1. The Chemistry of carbon compounds. 2.

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Organic Chemistry

2

Organic Chemistry

The Chemistry of carbon compounds.

3

Organic Chemistry


We will look at: (1) Naming of simple compounds.

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Organic Chemistry


We will look at: (1) Naming of simple compounds. (2) Some simple reactions.

5

Organic Chemistry


We will look at: (1) Naming of simple compounds. (2) Some simple reactions. (3) Some simple properties.

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Organic Chemistry


We will look at: (1) Naming of simple compounds. (2) Some simple reactions. (3) Some simple properties. (4) Some applications will be discussed.

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Naming simple organic compounds

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Organic compounds are organized in different families, and each family has a root name.

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Organic compounds are organized in different families, and each family has a root name. Compounds derived from the starting members in the family have their name based on the parent compound from which they are derived.

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The key compounds for naming are the hydrocarbons.

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The key compounds for naming are the hydrocarbons. There are three basic classifications and some important secondary classifications.

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(1) Alkanes

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(1) Alkanes (2) Alkenes

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(1) Alkanes (2) Alkenes (3) Alkynes

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Prefix systemused to name inorganic compounds. This is also used for organic compounds to name the number of substituents. The base names for the alkanes with five or more C atoms are derived directly from these names.

number prefix

1 mon*2 di3 tri4 tetra5 penta6 hexa7 hepta8 octa9 nona10 deca

*Often not employed.

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Prefix systemused to name the number of carbon atoms in the longest chain of organic compounds. Note that the ones in blue do not follow from the first four prefixes in the previous table. These entries are sometimes termed the roots for the number of C atoms.

number prefix

1 meth2 eth3 prop4 but5 pent6 hex7 hept8 oct9 non10 dec

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Names for organic compounds break up into two groups:

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Non-systematic (trivial)

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Non-systematic (trivial) Systematic (This will be our focus, though

some of the common names will be mentioned.)

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Non-systematic (trivial) Systematic (This will be our focus, though

some of the common names will be mentioned.)

Example: H2O

The non-systematic name is water. The systematic name is dihydrogen oxide.

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Number of bonds For the following atoms the typical number of

bonds from each atom is as follows:

Atom Number of bonds H 1 C 4

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Atom Number of bonds H 1 C 4 O 2 N 3

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Atom Number of bonds H 1 C 4 O 2 N 3 (Note: there are exceptions)

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The Alkanes

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The Alkanes

As far as naming is concerned, the alkanes are the top priority family.

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The Alkanes

As far as naming is concerned, the alkanes are the top priority family. Many other names are based on the names used for this group of compounds.

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The Alkanes

As far as naming is concerned, the alkanes are the top priority family. Many other names are based on the names used for this group of compounds.

The alkanes have the general formula CnH2n+2

where n = 1, 2, 3, ….

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Formula NameCH4 methane

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CH3CH3 ethane

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CH3CH3 ethane

CH3CH2CH3 propane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane

CH3CH2CH2CH2CH3 pentane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane


CH3CH2CH2CH2CH2CH3 hexane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane



CH3CH2CH2CH2CH2CH2CH3 heptane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane




CH3CH2CH2CH2CH2CH2CH2CH3 octane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane





CH3CH2CH2CH2CH2CH2CH2CH2CH3 nonane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3CH2CH2CH3 butane





CH3CH2CH2CH2CH2CH2CH2CH2CH3 nonane

CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 decane

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CH3CH3 ethane

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CH3CH3 ethane

CH3CH2CH3 propane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3(CH2)2CH3 butane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3(CH2)2CH3 butane

CH3(CH2)3CH3 pentane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3(CH2)2CH3 butane


CH3(CH2)4CH3 hexane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3(CH2)2CH3 butane


CH3(CH2)4CH3 hexane

CH3(CH2)5CH3 heptane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3(CH2)2CH3 butane


CH3(CH2)4CH3 hexane


CH3(CH2)6CH3 octane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3(CH2)2CH3 butane


CH3(CH2)4CH3 hexane


CH3(CH2)6CH3 octane

CH3(CH2)7CH3 nonane

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CH3CH3 ethane

CH3CH2CH3 propane

CH3(CH2)2CH3 butane


CH3(CH2)4CH3 hexane


CH3(CH2)6CH3 octane

CH3(CH2)7CH3 nonane

CH3(CH2)8CH3 decane

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Alkyl groups

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Alkyl groupsFormula Name

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Alkyl groupsFormula NameCH3 methyl

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CH3CH2 ethyl

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CH3CH2 ethyl

CH3CH2CH2 n-propyl

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CH3CH2 ethyl

CH3CH2CH2 n-propyl

CH3(CH2)2CH2 n-butyl

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CH3CH2 ethyl

CH3CH2CH2 n-propyl


CH3(CH2)3CH2 n-pentyl

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CH3CH2 ethyl

CH3CH2CH2 n-propyl


CH3(CH2)3CH2 n-pentyl

Ending change: ane yl (or add yl to the root names)

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In the previous list “n” stands for normal. In this case the bond is from the first carbon of the longest chain.

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In the previous list “n” stands for normal. In this case the bond is from the first carbon of the longest chain. Three other prefixes that occur commonly are:

sec- short for secondary

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sec- short for secondary tert- short for tertiary

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sec- short for secondary tert- short for tertiary iso (no hyphen is used)

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sec- short for secondary tert- short for tertiary iso (no hyphen is used) Examples:

HH

HHHHHH CCCC

Hsec-butyl

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HH

HHHHHH CCCC

H H

H

H

HH

H

C

CCC HH

sec-butyl

H

tert-butyl

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HH

HHHHHH CCCC

H H

H

H

H

HH

H

C

CCC HH HH

HH

HH

C

CCC

H

Hsec-butyl

H

tert-butyl isobutyl

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The term isoalkane is used to denote a branched chain alkane with a methyl group attached to the penultimate carbon atom of the main chain.

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The term isoalkane is used to denote a branched chain alkane with a methyl group attached to the penultimate carbon atom of the main chain.

As the number of carbon atoms increase, the prefixes become less useful, because an increasingly large number of prefixes would be needed. In this case, the standard numbering scheme (described about nine slides later) is used.

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Structures of some alkanes

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H

HHH C

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H

HHH C CC

H HH

HH

H

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H

HHH C

CCC

CCH

H

H

H

H

HH

HH

HH

H

HH

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H

HHH C

CCC

CCH

H

H

H

H

HH

HH

HH

H

HH HH

HHHHHH CCCC

HH

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These are straight chain examples.

H

HHH C

CCC

CCH

H

H

H

H

HH

HH

HH

H

HH HH

HHHHHH CCCC

HH

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These are straight chain examples. Note that the alkanes have only single bonds.

H

HHH C

CCC

CCH

H

H

H

H

HH

HH

HH

H

HH HH

HHHHHH CCCC

HH

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Branched alkanes

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Branched alkanes

HH

HHHHHH CCCC

H3CH

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Branched alkanes

4 3 2 1

HH

HHHHHH CCCC

H3CH

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Branched alkanes

4 3 2 1 2-methylbutane

(the 2 is a bit redundant)

HH

HHHHHH CCCC

H3CH

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Branched alkanes

4 3 2 1 2-methylbutane

(the 2 is a bit redundant)

Number the longest chain so as to give the lowest number to the substituent (in this case a methyl group) off the main chain.

HH

HHHHHH CCCC

H3CH

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HC

HH

HHHH HH CCCC H

3CH 3CH

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5 4 3 2 1

HC

HH

HHHH HH CCCC H

3CH 3CH

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5 4 3 2 1 2,3-dimethylpentane

HC

HH

HHHH HH CCCC H

3CH 3CH

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HC

H

HHHHH HH CCCC H

3CH 2CH

3CH

C C CH

HH

H H H

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Note: there is a methyl and an ethyl group off the main chain.

HC

H

HHHHH HH CCCC H

3CH 2CH

3CH

C C CH

HH

H H H

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1 2 3 4 5 6 7 8


HC

H

HHHHH HH CCCC H

3CH 2CH

3CH

C C CH

HH

H H H

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8 7 6 5 4 3 2 1 5 and 6 bigger than 3 and 4 – so this is wrong numbering


HC

H

HHHHH HH CCCC H

3CH 2CH

3CH

C C CH

HH

H H H

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1 2 3 4 5 6 7 8


HC

H

HHHHH HH CCCC H

3CH 2CH

3CH

C C CH

HH

H H H

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3-methyl-4-ethyloctane (complexity order)

1 2 3 4 5 6 7 8


HC

H

HHHHH HH CCCC H

3CH 2CH

3CH

C C CH

HH

H H H

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3-methyl-4-ethyloctane (complexity order) 4-ethyl-3-methyloctane (alphabetical order)

1 2 3 4 5 6 7 8


HC

H

HHHHH HH CCCC H

3CH 2CH

3CH

C C CH

HH

H H H

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Summary of the simple rules to name an alkane. Prefix + root + suffix

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Ways of depicting an alkane (p. 578)

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The impact of free rotation about carbon – carbon single bonds.

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Exercise: Draw the structures of (1) 2,2,3-trimethylbutane (2) 4-ethyl-2-methylnonane (2-methyl-4-ethylnonane) (3) 2,4-dimethyloctane

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Physical properties of the alkanes

The series of straight-chain alkanes shows a very smooth gradation of physical properties. As the series is ascended, each additional CH2 group contributes a fairly constant increment to the boiling point and to the density – and to a lesser extent to the melting point.

This makes it possible to estimate the properties of an unknown member of the series from those of its neighbors.

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Alkenes

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Alkenes These are hydrocarbons with at least one or

more double bonds.

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more double bonds.

The parent alkanes are used to name the alkene family of compounds.

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more double bonds.

The parent alkanes are used to name the alkene family of compounds.

The name ending change is: ane ene

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alkane alkene structure ethane ethene

CCHH

HH

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alkane alkene structure ethane ethene

propane propene

CCHH

HH

3CHCC

H H

H

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alkane alkene structure butane butene

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alkane alkene structure butane butene In this case there are three possible compounds.

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alkane alkene structure butane butene In this case there are three possible compounds. 1-butene

C CH

HH

3CH2CH

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alkane alkene structure butane butene In this case there are three possible compounds. 1-butene The number 1 indicates on which carbon the double bond starts.

C CH

HH

3CH2CH

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alkane alkene structure butane butene In this case there are three possible compounds. 1-butene The number 1 indicates on which carbon the double bond starts. 2- butene

C CH

HH

3CH

HH

2CH

3CH3CHCC

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alkane alkene structure butane butene In this case there are three possible compounds. 1-butene The number 1 indicates on which carbon the double bond starts. 2- butene

C C

H

H

HH

3CH

C C

H

H

H

2CH

3CH3CH

3CH

3CH

CC

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alkane alkene structure butane butene In this case there are three possible compounds. 1-butene The number 1 indicates on which carbon the double bond starts. 2- butene cis-2-butene

trans-2-butene

C C

H

H

HH

3CH

C C

H

H

H

2CH

3CH3CH

3CH

3CH

CC

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Z and E isomers

Some cases arise in which it is very difficult to name a compound unambiguously, e.g.

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Z and E isomers


BrC C

I 3CH

Cl

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Z and E isomers


Is this a cis or trans compound?

BrC C

I 3CH

Cl

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Z and E isomers



A way to sort out this problem is to use the symbols

BrC C

I 3CH

Cl

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Z and E isomers



A way to sort out this problem is to use the symbols Z (zusammen = together)

BrC C

I 3CH

Cl

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Z and E isomers



A way to sort out this problem is to use the symbols Z (zusammen = together) E(entgegen = opposite)

BrC C

I 3CH

Cl

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Rules1. Compare the two groups on one carbon atom of

the carbon-carbon double bond.

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the carbon-carbon double bond.2. Assign the two groups priorities using the Cahn-

Ingold-Prelog rules for R and S configurations.

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Ingold-Prelog rules for R and S configurations.3. Repeat steps 1 and 2 for the second carbon of the

carbon-carbon double bond.

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Ingold-Prelog rules for R and S configurations.3. Repeat steps 1 and 2 for the second carbon of the

carbon-carbon double bond.4. If the two groups of highest priority are on the

same side of the double bond, we have the Z isomer. If the two groups are on opposite sides we have the E isomer.

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Arrange the atoms in decreasing order of atomic number, e.g. I, Br, Cl, S, P, F, O, N, C, H

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Z-2-butene

HH

3CH3CHCC

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Z-2-butene

E-2-butene

HH

3CH3CHCC

HC C

H 3CH

3CH

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Z-2-butene

E-2-butene

E-2-bromo-1-chloro-1-iodopropene

HH

3CH3CHCC

HC C

H 3CH

3CH

ClC C

I3CH

Br

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Z-2-butene

E-2-butene

E-2-bromo-1-chloro-1-iodopropene The group of highest priority on each C atom is

circled.

HH

3CH3CHCC

HC C

H 3CH

3CH

ClC C

I3CH

Br

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Z-2-butene

E-2-butene

E-2-bromo-1-chloro-1-iodopropene The group of highest priority on each C atom is

circled.

HH

3CH3CHCC

HC C

H 3CH

3CH

ClC C

I3CH

Br

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alkene condensed formula ethene CH2CH2

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propene CH2CHCH3

123


propene CH2CHCH3

1-butene CH2CHCH2CH3

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propene CH2CHCH3


2-butene CH3CHCHCH3

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propene CH2CHCH3


2-butene CH3CHCHCH3

Note: it would not be clear from the formula for 2-butene whether this is the cis or trans compound.

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propene CH2CHCH3


2-butene CH3CHCHCH3

Note: it would not be clear from the formula for 2-butene whether this is the cis or trans compound. This is a reason why structures are very useful!

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It is possible to have more than one double bond present. For example:

1,3-butadiene

CCCC H

H H

H

H

H

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Alkynes

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Alkynes The alkynes have one or more triple bonds.

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Alkynes The alkynes have one or more triple bonds. The ending change is: ane yne

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Alkynes The alkynes have one or more triple bonds. The ending change is: ane yne The alkenes and the alkynes are referred to as

unsaturated hydrocarbons.

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Alkynes The alkynes have one or more triple bonds. The ending change is: ane yne The alkenes and the alkynes are referred to as

unsaturated hydrocarbons.

Unsaturated hydrocarbon: A hydrocarbon having one or more double or triple bonds.

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alkane alkyne structure ethane ethyne

CCH H

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propane propyne

CCH H

H 3CHCC

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propane propyne

butane 1-butyne

CCH H

H 3CHCC

H CC 2CH 3CH

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propane propyne

butane 1-butyne 2-butyne

CCH H

H 3CHCC

H CC 2CH 3CHCC3CH 3CH

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alkyne condensed formula ethyne C2H2

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propyne CHCCH3

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propyne CHCCH3

1-butyne CHCCH2CH3

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propyne CHCCH3

1-butyne CHCCH2CH3

2-butyne CH3CCCH3

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propyne CHCCH3

(Writing C3H4 would not be useful.)

1-butyne CHCCH2CH3

2-butyne CH3CCCH3

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propyne CHCCH3

(Writing C3H4 would not be useful. Why?)

1-butyne CHCCH2CH3

2-butyne CH3CCCH3

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Explanation of why C3H4 would not be useful.

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Clearly, this could be propyne.

CCH 3CH

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But it could also be

CCH

HHCCC

H H

3CH

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1,2-propadiene

CCH

HHCCC

H H

3CH

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1,2-propadiene (The numbering would be a bit redundant in this

example.)

CCH

HHCCC

H H

3CH

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Cycloalkanes

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Cycloalkanes

The cyclo compounds have a ring of carbon atoms present in the compound.

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alkane cycloalkane structure propane cyclopropane

CC

HH

HH

CHH

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alkane cycloalkane structure propane cyclopropane

butane cyclobutane

CC

HH

HH

C

C

H HH

HH

CCC

HHH HH

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Conformational possibilities for cyclohexane

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Some substituents

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Some substituents

Substituent Name F fluoro

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Some substituents

Substituent Name F fluoro Cl chloro

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Some substituents

Substituent Name F fluoro Cl chloro Br bromo

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Some substituents

Substituent Name F fluoro Cl chloro Br bromo I iodo

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Some substituents

Substituent Name F fluoro Cl chloro Br bromo I iodo

Note: the ending change ide o as in chloride to chloro

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Name the following

166

Name the following1.

H

HFH C

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2.

H

HFH C

CCH F

FH

HH

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2.

3.

H

HFH C

CCH F

FH

HH

CCCH

F

H

H

HH F

Cl

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2.

3.

4.

BrH

HBrHHHH CCCC

BrH

H

HFH C

CCH F

FH

HH

CCCH

F

H

H

HH F

Cl

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Name the following1. fluoromethane

2.

3.

4.

BrH

HBrHHHH CCCC

BrH

H

HFH C

CCH F

FH

HH

CCCH

F

H

H

HH F

Cl

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2. 1,1-difluoroethane

3.

4.

BrH

HBrHHHH CCCC

BrH

H

HFH C

CCH F

FH

HH

CCCH

F

H

H

HH F

Cl

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3. 1-chloro-1,2-difluoropropane

4.

BrH

HBrHHHH CCCC

BrH

H

HFH C

CCH F

FH

HH

CCCH

F

H

H

HH F

Cl

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3. 1-chloro-1,2-difluoropropane

4. 1,2,3-tribromobutane

BrH

HBrHHHH CCCC

BrH

H

HFH C

CCH F

FH

HH

CCCH

F

H

H

HH F

Cl

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3. 1-chloro-1,2-difluoropropane*

4. 1,2,3-tribromobutane* *(there is more than one form of this compound)

BrH

HBrHHHH CCCC

BrH

H

HFH C

CCH F

FH

HH

CCCH

F

H

H

HH F

Cl

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Some simple reactions of alkanes, alkenes, and alkynes

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Combustion: CH4 + 2 O2 CO2 + 2 H2O

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When the products are CO2 and H2O it is termed a complete combustion.

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With insufficient O2, CO will be formed. E. g.

2 CH4 + 3 O2 2 CO + 4 H2O

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With insufficient O2, CO will be formed. E. g.

2 CH4 + 3 O2 2 CO + 4 H2O

This is called an incomplete combustion.

Organic Chemistry 1. The Chemistry of carbon compounds. 2.

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Transcript of Organic Chemistry 1. The Chemistry of carbon compounds. 2.