chemistryatkanehs.weebly.comchemistryatkanehs.weebly.com/.../chapter_19_notes_-_…  · Web viewIntroduction to General, Organic, and Biochemistry ... Combustion . Aside from their

Chapter 19: Organic Chemistry and Hydrocarbons Name__________________________

Introduction to General, Organic, and Biochemistry Hein * Best * Pattison * Arena

Organic Chemistry

Historically, organic chemicals were defined as those that came from living sources. These chemicals could only originate from a _____________.

Friedrich Wohler then synthesized urea from _____________ and _________thus disputing the vital force theory.

– Equation:

Organic chemistry is now defined as the branch of chemistry dealing with _________________ (ie, no _______________needed!)

Certain carbon compounds are not organic: ______________, ________________, _______________

Carbon, in combination with hydrogen, oxygen, nitrogen, and sulfur, forms the basis for

Carbon is unique in that it can bond to itself in lengthy chains (a process called ___________________________).

Organic molecules make up the majority of:1.

2.

3.

4.

5.

6.

7.

1

The Carbon Atom: Bonding and Shape• The carbon atom is central to all organic compounds.

• A carbon atom usually forms four covalent bonds.– Single bonds

• Ex: – Double bonds

• Ex: – Triple bonds

• Ex:• An organic compound is classified as saturated if it contains only ____________.

– Ex:

• An organic compound is classified as unsaturated if the ____________________ _______________________________.

– Ex:

– Ex:

The Shapes of Carbon-Containing Compounds• Valence Shell Electron Pair Repulsion theory (VSEPR)

– VSEPR theory states that

– The electron pairs will try to __________________________________________.

Figure 19.1 Shows a) ________________________ b) ________________________________________________________

c) ________________________________________________________

d) ________________________________________________________

2

Double bond: Figure 19.2 (a) ____________________________________________ (b) _______________________________________________

180°

H:C:::C:H or C C HH Triple bond: the carbon has only two regions for shared electrons. To be placed as far apart as possible, a _______________________________

Molecular Models

Models are often used in organic chemistry to illustrate molecules.

Figure 19.3 shows____________________________________________

Figure 19.4 Models of ______________show

(a) _________________________

(b) _________________________

(c) _________________________

(d) _________________________

Structural formulasIn a _______________, the ______________________________________.

– Ex:

These structural formulas are often shortened into ________________________– Ex:

3

Classes of Organic Compounds (table 19.1)

4

Classifying Organic Compounds

Functional groupsThe members of each class of compounds contain __________________________ ___________________________________________________________________called a functional group. These are shown in red in the structural formulas on the table.

Organic compounds with similar structures are grouped into classes as shown in Table 19.1.

For example, the functional group for

• An ether is ___________________________

• An alcohol is__________________________

• An alkene is __________________________

• A carboxylic acid is __________________________

• A functional group:

Hydrocarbons

Hydrocarbons are

Fossil fuels -

• Hydrocarbons are classified into two major categories, aliphatic and aromatic.

– aliphatic

– aromatic

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Saturated hydrocarbons – Alkanes

The alkanes, also known as _____________________ or __________________________, are

They may be “straight chained”

Or they may be “branched”

Homologous Series

A homologous series is

Members of a homologous series are

General formula for homologous series:

Do you need to memorize boiling points and melting points? What do you need to know?

6

Carbon bonding in Alkanes

Figure 19.7 The tetrahedral nature of sp3 orbitals: (a) ______________________________________

(b) _______________________________________

(c) _______________________________________

Sigma Bonding• a sigma () bond is a

• A sigma bond exists if

Pi bonding• A pi bond () is

Number of bonds around carbon and other elements common in organic chemistry

The valence bonds may be represented in structural formulas by a corresponding number of lines attached to each atom: Note how many bonds are always attached to each atom and how many non-bonded electrons are also implied to satisfy the octet rule. carbon nitrogen oxygen hydrogen sulfur halogens

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Alkane molecules are non-polar.– Carbon-carbon bonds are non-polar, since _____________________________– Carbon-hydrogen bonds are only slightly polar. (which means

_________________ ____________– The bonds in an alkane are symmetrically directed toward

______________________.– In virtue of their low polarity, alkane molecules have relatively _______________

____________________________________

Figure 19.8 _____________________________________

Write the correct structural formula (full & condensed) for butane (C4H10) and pentane (C5H12)

ISOMERISM

It is possible to write two structural formulas corresponding to the molecular formula C4H10:

• Isomerism is defined as

• The various individual compounds are called isomers.– e.g. ____________________

• Isomers are

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Figure 19.8 Ball-and-stick models illustrating structural formulas of butane and isobutene

Example for Drawing Isomers

There are three isomers of pentane, C5H12. Write structural formulas and condensed structural formulas for these isomers

Using method described above to write the structural formulas and condensed structural formulas for C6H14

Naming Organic Compounds: IUPAC System for Naming Organic Compounds9

• The method recommended by the _______________________________ _______________________________ is systematic, generally unambiguous, and internationally accepted.

• Some trivial or common names are still used.

Alkyl Groups

• Alkyl groups have the general formula ________ (one less hydrogen than the corresponding alkane).

• Alkyl groups are NOT ________________, they are ____________________________

• The name of the group is formed from the name of the corresponding alkane by simply dropping the ____ ending and substituting a _____ ending.

CH4 = -CH3 =

• The letter R is often used in formulas to mean _____________________________

Ex:

Ethane Ethyl

Propane Propyl

Butane Butyl

Pentane Pentyl

Hexane Hexyl

ISOMERS of propyl and butyl groups10

Primary (1°), Secondary (2°), and Tertiary (3°) Carbon Atoms

IUPAC Rules for Naming Alkanes11

1. Select the longest continuous chain of carbon atoms as the parent compound, and consider all alkyl groups attached to it as branch chains that have replaced hydrogen atoms of the parent hydrocarbon. The name of the alkane consists of the name of the parent compound prefixed by the names of the branch-chain alkyl groups attached to it.

2. Number the carbon atoms in the parent carbon chain from one end to the other, starting at the end closest to the first carbon atom that has a branch chain.

3. Name each branch-chain alkyl group and designate its position on the parent carbon by a number.

4. When the same alkyl-group branch chain occurs more than once, indicate this by a prefix (di-, tri-, tetra-, etc.) written in front of the alkyl group name (e.g. dimethyl indicates two methyl groups). The numbers indicating the positions of these alkyl groups are separated by a comma, followed by a hyphen, and placed in front of the name.

5. When several different alkyl groups are attached to the parent compound, list them in alphabetical order (e.g. ethyl before methyl)

Name the following alkanes:

Write the formula for 3-ethylpentane

Write the formula for 2,2,4-trimethylpentane

Introduction to the Reactions of Carbon

One of the most important carbon reactions is oxidation – reduction12

H3C

H2C

CHCH

CH

H2C

CH2

CH2

H2C

H2C

CH3

CH3

CH3

CH3H3CCH

CH2

H2C

CH2

CH3

CH3

The longest continuous chain is 6 carbons; the parent hydrocarbon is hexane.

Oxidation When carbon atoms are __________, they often form________________________.

ReductionWhen carbon atoms are __________,they often form ______________________.

Other reactions of carbon

1. Substitution reactions

2. Elimination reactions

3. Addition reactions

Reactions of Alkanes

Combustion

13

Aside from their combustibility, alkanes are relatively sluggish and limited in reactivity. With proper activation, such as with high temperature or catalysts, alkanes can be made to react in a variety of ways.

Some Important Noncombustion Reactions of Alkanes

• Halogenation

• Dehydrogenation

• Cracking

• Isomerization

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Alkyl Halides• The formula RX indicates

• Ex:

Sources of Alkanes:

The two main sources of alkanes are _______________and _________________

– Natural gas is formed

– Petroleum

Gasoline: A Major Petroleum Product

Uses of petroleum:

15

Cycloalkanes:

• Cycloalkanes

• Their names are formed

With the exceptions of ______________and _____________, cycloalkanes are generally

Cycloalkanes are ___________ hydrocarbons; they contain

There is a greater reactivity in cyclopropane and cyclobutane because

Naming Cycloalkanes• Substituted cycloalkanes are named by identifying and numbering the location of the

substituent(s) on the carbon ring, followed by the name of the parent alkane.• Substituted cycloalkanes are named by identifying and numbering the location of the

substituent(s) on the carbon ring, followed by the name of the parent alkane.

CH3

1,1-dimethylcyclohexane

CH3

CH3

1,2-dimethylcyclohexaneCH3

CH3H3C

1,3-dimethylcyclohexaneCH3

1,4-dimethylcyclohexaneH3C

CH3

1,1-dimethylcyclohexane

CH3

CH3

1,2-dimethylcyclohexaneCH3

CH3H3C

1,3-dimethylcyclohexaneCH3

1,4-dimethylcyclohexaneH3C

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