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Introduction to Organic :

Chapter 12

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Chapter 12

12.1 – Organic Compounds 12.2 – Alkanes 12.3 – Alkanes with 12.4 – Properties of Alkanes 12.5 – and 12.6 – Cis-Trans 12.7 – Addition Reactions for Alkenes 12.8 – Aromatic Compounds

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved 12.1 – Organic Compounds Identify properties characteristic of organic or inorganic compounds.

Organic Compounds

Organic chemistry is the study of compounds. An

• Always contains carbon and

• May also contain other nonmetals such as , , , or a .

• Organic compounds are found in: • , medicines, shampoos, , and perfumes • , , and proteins Functional Groups

• Organic compounds are organized by their functional groups (groups of atoms bonded in a specific way).

• Compounds that contain the same functional groups have similar physical and chemical properties.

• The identification of functional groups allows us to classify organic compounds according to their structure, to name compounds within each family, and to predict their chemical reactions.

Organic vs. Inorganic

• In chemistry, are classified as Organic or Inorganic.

• Inorganic compounds are (quite expansively) anything that is not organic.

• Organic and Inorganic compounds have different properties. – Organic compounds: ƒ Have low melting and boiling points. ƒ Are flammable and undergo . ƒ Are not soluble in . – Inorganic compounds ƒ Many inorganic compounds have high melting and boiling points. ƒ Inorganic compounds that are ionic are usually soluble in water, and most do not burn in air. Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved

Practice

Identify each characteristic as most typical of compounds that are inorganic or organic. A. It has a high . B. It is not soluble in water. C. It contains carbon and hydrogen atoms.

D. It has the formula MgCl2. E. It burns easily in air.

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• Hydrocarbons are organic compounds that consist of only carbon and hydrogen. – In organic molecules, every carbon has four bonds. – In (CH4), the carbon atom forms an octet by sharing its four electrons with four hydrogen atoms.

Three-dimensional and two-dimensional representations of methane: a) space-filling model, b) ball-and-stick model, c) wedge-dash model, d) expanded , and e) condensed structural formula

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Representations of Carbon Compounds

• In (C2H6), each tetrahedral carbon forms three covalent bonds to hydrogen and one to the other carbon.

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Alkanes

• are formed by a continuous chain of carbon atoms. • are named using the IUPAC (International Union of Pure and Applied Chemistry) system. • have names that end in ane. • use Greek prefixes to name carbon chains with five or more carbon atoms.

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Study Check

In the (C4H10), predict the shape around each carbon atom.

H H H H

H C C C C H

H H H H

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Chapter 12

12.1 – Organic Compounds 12.2 – Alkanes 12.3 – Alkanes with Substituents 12.4 – Properties of Alkanes 12.5 – Alkenes and Alkynes 12.6 – Cis-Trans Isomers 12.7 – Addition Reactions for Alkenes 12.8 – Aromatic Compounds

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12.2 - Alkanes

Write the IUPAC names and draw the condensed or line-angle structural formulas for alkanes and .

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• More than 90% of the compounds in the world are organic compounds.

• The larger number of carbon compounds is possible because the covalent bonds between carbon atoms (C-C) is very strong, allowing carbon atoms to form long, stable chains.

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Alkanes

• The alkanes are a type of in which the carbon atoms are connected only by single bonds. – Alkanes are formed by a continuous chain of carbon atoms. – The names of alkanes and in –ane. ƒ Such names are part of the IUPAC system (International Union of Pure and Applied Chemistry) used by chemists to name organic chemistry. – Alkanes made of carbon chains are named based on how many make up the chain.

– One of the most common uses of alkanes is as . ƒ Methane, , , and are all alkanes used as fuels.

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved IUPAC Names of Alkanes

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Line-Angle Structural Formulas

A simplified structure of organic molecules • is called the line-angle structural formula. • shows a zigzag line in which carbon atoms are represented as the ends of each line and as corners.

Carbon atoms • at the end are bonded to three hydrogen atoms. • in the middle are bonded to two hydrogen atoms.

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Condensed formula and Line-angle formula

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Condensed formula and Line-angle formula

• Draw the condensed structural formula and name the molecule:

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Guide to Drawing Structural Formulas for Alkanes

Step 1: Draw the carbon chain. Step 2: Draw the expanded structural formula by adding the hydrogen atoms using single bonds to each of the carbon atoms. Step 3: Draw the condensed structural formula by combining the H atoms with each C atom. Step 4: Draw the line-angle structural formula as a zigzag line in which the ends and corners represent C atoms.

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Drawing Expanded, Condensed, and Line- Angle Structural Formulas (1 of 3)

Draw the expanded, condensed, and line-angle structural formula for pentane. Step 1: Draw the carbon chain. A molecule of pentane has five carbon atoms in a continuous chain.

Step 2: Draw the expanded structural formula by adding the hydrogen atoms, using single bonds to each of the carbon atoms.

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Draw the expanded, condensed, and line-angle structural formula for pentane. Step 3: Draw the condensed structural formula by combining the H atoms with each C atom.

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Drawing Expanded, Condensed, and Line- Angle Structural Formulas (3 of 3)

Draw the expanded, condensed, and line-angle structural formula for pentane. Step 4: Draw the line-angle structural formula as a zigzag line in which the ends and corners represent C atoms.

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• Single bonds can spin and rotate.

• Thus different arrangements, known as conformations, occur during the rotation about a .

• http://symmetry.otterbein.edu/gallery/index.html

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Structural Formulas: C4H10

As butane (C4H10) rotates, sometimes the line up in front of each other, and at other times they are opposite each other. Butane can be drawn using a variety of two-dimensional condensed structural formulas:

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Cycloalkanes

Hydrocarbons can also form into circles or rings called: cycloalkanes • have two fewer hydrogen atoms than the open chain form. • are named by using the prefix cyclo before the name of the alkane chain with the same number of carbon atoms.

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Table 12.4 Formulas of Some Common Cycloalkanes Name BLANK BLANK BLANK Ball-and-Stick Model BLANK BLANK BLANK

Three carbons single-bonded to each other in a triangular pattern, The ball and stick model shows four The ball and stick model shows five The ball and stick model shows six with each carbon single-bonded to 2 . carbons single-bonded to each other in a carbons single-bonded to each other in carbons single-bonded to each other in square pattern, with each carbon single- a pentagonal pattern, with each carbon a hexagonal pattern, with each carbon single-bonded to 2 hydrogens. bonded to 2 hydrogens. single-bonded to 2 hydrogens.

Condensed Structural Formula BLANK BLANK BLANK

The condensed structural formula shows a triangular ring of three C The condensed structural formula shows The condensed structural formula The condensed structural formula H 2 molecules. a square ring of four C H 2 molecules. shows a pentagonal ring of five C H 2 shows a hexagonal ring of six C H 2 molecules. molecules.

Line-Angle Structural Formula BLANK BLANK BLANK

The line-angle structural formula is a triangle. The line-angle structural formula shows a The line-angle structural formula shows The line-angle structural formula shows square. a hexagon. a pentagon.

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Study Check

Give the IUPAC name for each of the following compounds:

A.

B.

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Name the following alkanes: A.

B. C.

D.

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Chapter 12

12.1 – Organic Compounds 12.2 – Alkanes 12.3 – Alkanes with Substituents 12.4 – Properties of Alkanes 12.5 – Alkenes and Alkynes 12.6 – Cis-Trans Isomers 12.7 – Addition Reactions for Alkenes 12.8 – Aromatic Compounds

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved 12.3 – Alkanes and Substituents

Write the IUPAC names for alkanes with substituents and draw their condensed and line-angle structural formulas.

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Structural Isomers

Structural isomers • have the same molecular formula with a different arrangement of atoms. • have the same number of atoms bonded in a different order.

Butane (C4H10) has two structural isomers: a straight chain and a branched chain.

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Draw three possible structural isomers of pentane

(C5H12).

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Solution

Draw three possible structural isomers of pentane

(C5H12).

Structural Structural Isomers of C5H12 Structural Isomers of Structural Isomers Isomers of C5H12 of C5H12 C5H12

The first condensed structural formula is a straight chain of single-bonded molecules as follows. C H 3, C H 2, C H 2, C H 2, C H 3. The second condensed structural formula is a branched chain as follows. C H 3, C H single-bonded to C H 3 above, C H 2, C H 3. The third condensed structural formula is a central C single-bonded to four C H 3 molecules above, below, Condensed rightward, and leftward.

The line-angle structural formula shows a zigzag line made of 4 segments forming 3 angles. The line-angle structural formula shows a zigzag of 3 segments forming 2 angles, with The line-angle structural formula shows 2 rising and falling line Line-Angle a fourth segment rising vertically from the first angle. segments with 2 segments rising diagonally right and left from the angle.

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Study Check Is the pair of formulas structural isomers? Or the same molecule?

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Substituents in Alkanes

• When CH3 branches off of a carbon chain, it’s called an group

• When a halogen atom (Group 17) is attached to a carbon chain, it is named as a halo group with the terms –fluoro, -chloro, -bromo, -iodo based on which element it is.

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Substituents and Alkyl Groups

Table 12.5 Formulas and Names of Some Common Substituents

Formula, C H 3, single bond. name, methyl. Formula Formula, straight chain, C H 3, C H 2, single BLANK BLANK Name bond. name, ethyl.

Formula, straight chain, C H 3, C H 2, C H 2, single bond. name, Formula, branched chain, C H 3, C H with single bond above, C Formula propyl. BLANK BLANK H 3. name, isopropyl. Name

Formula, straight chain, C H 3, C H 2, C H 2, C H 2, single bond. Formula, branched chain, C H 3, C H single-bonded to C H 3 Formula, C H 3, C H with single bond above, C H 2, Formula, central C with single bond name, butyl. above, C H 2, single bond. name, isobutyl. C H 3. name, butyl. above and three C H 3 molecules Formula below, rightward, and leftward. Name name, butyl.

Formula, F, single bond. name, fluoro. Formula, F, single bond. name, fluoro. Formula, B r, single bond. name, bromo. Formula, I, single bond. name, iodo. Formula Name

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Naming Alkanes with Substituents

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Naming Alkanes with Substituents

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Naming Cycloalkanes with Substituents

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Naming Cycloalkanes with Substituents

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Naming

Haloalkanes • are alakanes with a halogen atom that replaces a hydrogen atom. • are named by putting the substituents in alphabetical order. • have the halo group numbered according to the carbon where it is attached to the alkane.

Examples of BLANK BLANK BLANK BLANK Haloalkanes

straight chain, C H 3, C l straight chain, C H 3, C H 2, B r Branched chain, C H 3, C H single-bonded to an F above A central C single-bonded to C l above and three C H 3 molecules below, rightward, and leftward Formula

IUPAC Chloromethane Bromoethane 2-Fluoropropane 2-Chloro-2- methylpropane

Common Methyl chloride Ethyl bromide Isopropyl fluoride Tert-Butyl chloride

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Drawing the molecule from the name

Draw the condensed and line-angle structural formulas for 2,3-dimethylbutane.

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Drawing the molecule from the name

Draw the condensed and line-angle structural formulas for 2-bromo-3-ethyl-4-methylpentane.

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Chapter 12

12.1 – Organic Compounds 12.2 – Alkanes 12.3 – Alkanes with Substituents 12.4 – Properties of Alkanes 12.5 – Alkenes and Alkynes 12.6 – Cis-Trans Isomers 12.7 – Addition Reactions for Alkenes 12.8 – Aromatic Compounds

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12.4 – Properties of Alkanes

Identify the properties of alkanes and write a balanced chemical equation for combustion.

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Many types of alkanes are the components of fuels that power our cars and that heats our home. The solid alkanes that make up waxy coatings on fruits and vegetables help retain moisture, inhibit mold, and enhance appearance. The different uses of alkane compounds result from their physical properties, including their and density.

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Uses of Alkanes (1 of 2)

Alkanes with one to four carbons are gases at room temperature and are widely used as heating fuels. methane, ethane, propane, butane Butane has four carbons: Alkanes with five to eight carbons are highly volatile liquids at room temperature, which makes them useful as fuels. pentane, hexane, , octane Octane has eight carbons:

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Alkanes with 9−17 carbons are liquids with higher boiling points and are found in motor , , , diesel, and jet fuels. has 10 carbons:

• Alkanes with 18 or more carbon atoms, known as paraffins, are waxy solids at room temperature. • jelly, or Vaseline, is a semisolid of hydrocarbons with more than 25 carbon atoms.

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Melting and Boiling Points (1 of 4)

Alkanes • have the lowest melting and boiling points of organic compounds. • contain only the nonpolar bonds of • exhibit only weak dispersion forces in the solid and liquid states.

Longer-chain alkanes have more dispersion forces.

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Branched alkanes • have lower boiling points than the straight-chain isomers.

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Melting and Boiling Points (2 of 4)

Branched alkanes • have lower boiling points than the straight-chain isomers. • tend to be more compact, reducing the points of contact between the molecules. • do not have linear shapes and cannot line up close to each other.

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Cycloalkanes • have higher boiling points than the straight-chain alkanes with the same number of carbon atoms. • have limited rotation of carbon bonds; they maintain their rigid structure and can be stacked closely together, which gives them many points of contact and attractions to each other.

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Melting and Boiling Points (4 of 4)

We can compare the boiling points of straight-chain alkanes, branched-chain alkanes, and cycloalkanes. Table 12.6 Comparison of Boiling Points of Alkanes and Cycloalkanes with Five Carbons

Formula Name (°C) Straight-Chain Alkane BLANK BLANK

S traight chain alkanes. condensed structural formula, C H 3, C H 2, C H 2, C H 2, C H 3 Pentane 36 Branched-Chain Alkanes BLANK BLANK

B ranched chain alkanes. condensed structural formula, C H 3, C H single-bonded to C H 3, C H 2, C H 3 2-Methylbutane 28

Central C single-bonded to four C H 3 molecules Dimethylpropane 10

Cycloalkane BLANK BLANK

line-angle structural formula, a pentagonal ring Cyclopentane 49

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The carbon–carbon single bonds in alkanes are difficult to break, which makes them the least reactive family of organic compounds. However, alkanes burn readily in oxygen to produce , water, and energy.

Alkane gg' O2 CO2 g  H2O g + energy

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Combustion of Alkanes (3 of 3)

Methane is the we use to cook our food and heat our homes. The equation for the combustion of methane (CH4) is written as follows:

CH4222 ggg ' 2O CO  2H O g + energy Propane is the gas used in portable heaters and gas barbecues. The equation for the combustion of propane

(C3H8) is written as follows:

CH42 gg ' 5O 3CO 22 g  4H O g + energy

Copyright © 2016, 2013, 2010 Pearson Education, Inc. All Rights Reserved Solubility and Density of Alkanes

Alkanes are • nonpolar. • insoluble in water. • less dense than water. • flammable in air. • found in crude oil. If there is an oil spill in the ocean, the alkanes in the crude oil do not mix with the water but float on top, forming a thin layer on the surface.

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Chapter 12

12.1 – Organic Compounds 12.2 – Alkanes 12.3 – Alkanes with Substituents 12.4 – Properties of Alkanes 12.5 – Alkenes and Alkynes 12.6 – Cis-Trans Isomers 12.7 – Addition Reactions for Alkenes 12.8 – Aromatic Compounds

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