2202 2 alkenes and alkynes 2017...

2202 2 Alkenes and Alkynes 2017 Filled.notebook

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May 29, 2017

Feb 124:00 PM

Alkenes and Alkynes

Lesson 2


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Feb 124:00 PM

Alkenes (CnH2n)

• unsaturated compounds - organic compounds that contain double bonds

•General formula: CnH2n


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Feb 124:04 PM

General formula: CnH2n-2

Alkynes (CnH2n-2)• Unsaturated compounds - organic compounds

that contain triple bonds


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May 29, 2017

Unsaturation of Hydrocarbons.

Unsaturation of Hydrocarbons

Drag the chemical structure into the boxes, then touch the degree of unsaturation.

Alkane

Alkene

Alkyne

1 2

20

10

Organic Name Structure Degree of Unsaturation

0

1

22

1

0H

HH

C CHH

HHH

HH

C C

H C HC

Unsaturated hydrocarbons are hydrocarbon chains with one or more double or triple bonds between carbon atoms. Each double bond is the equivalent of one degree of unsaturation, while each triple bond is equal to two degrees of unsaturation.

Saturated hydrocarbons are hydrocarbon chains in which all carboncarbon bonds are single covalent bonds. Or, each carbon atom is completely saturated with the maximum number of hydrogen that can be accommodated.


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May 29, 2017

Answer

Alkane

Alkene

Alkyne

0

1

2

HHH

C CHH

H

H

H

H

HC C

H C HC

1

1

2

2

0

0

Organic Name Structure Degree of Unsaturation

Answer


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May 29, 2017

Naming Scheme for Hydrocarbons

Naming Scheme for Hydrocarbons

Pull the tabs for information and labeling instructions.

Hydrocarbons are named according to the number of carbons in the longest chain, the number and location of double and triple bonds, and the location of any functional groups attached to the longest chain.

1. Number the carbons in the longest chain. 2. Circle the double/triple bonds. 3. Put a box around any important functional groups (or carbons)4. Guess and write in the systematic (IUPAC) name.5. Erase the blue shading under the line to reveal the answer.


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Feb 124:10 PM

Ex1:Name the following structure:


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Feb 124:16 PM

Ex 2: Name the following structureA. B.

C. D.


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Feb 124:22 PM

Ex3: Draw a structural formula for 2-ethyl-1-pentene


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Feb 124:25 PM

Ex 4: Draw a structural formula for each name given.a) 1pentene b) 2pentene

c) 3 hexyne d) 2octene


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Feb 124:29 PM

e) 4octyne f) 2 butene

g) 2,2dimethyl3hexene


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Feb 124:34 PM

Cyclic alkenes (Cycloalkenes):Rings that possess a double carbontocarbon bond. Ex 5: Draw the full structural formula, condensed structural formula, and line drawing for cyclobutene.

HH

H

HH

H


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Feb 125:46 PM

Naming Cyclic alkenes 1. Count the number of carbon atoms in the ring.2. Name the structure the same as naming alkene but add the prefix cyclo to the alkene name.

Ex 6: Name this compound.

Answer: cyclohexene


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Feb 125:48 PM

Ex 7: Write the possible structural isomers for following molecular formulas.a) C4H8


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Feb 227:11 PM

b) C4H6


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Feb 125:49 PM

Geometric Isomerism• Isomers of alkenes that differ only in the arrangement of their substituted groups

• Possible whenever each carbon of the double bond has at least one substituent

• Isomers will differ with respect to their physical and chemical properties


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Feb 125:52 PM

• Cis – substituted groups are on the same side of the double bond

• Trans - substituted groups are on opposite sides of the double bond


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Feb 125:54 PM

Ex 8: Draw structural formulas for and provide names for five of the possible structural isomers of C6H12.Answer:


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Feb 126:00 PM

Alkene Properties1. React quickly with small, diatomic molecules (ie hydrogen, halogens)

F2, Cl2, Br2, I2, At2


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Feb 126:03 PM

2. Participates in:addition reactions – converts unsaturated

hydrocarbons to saturated hydrocarbons hydrogenation – addition reactions which

convert unsaturated hydrocarbons to saturated ones by the addition of hydrogen only. Used as starting materials in the petrochemical industry for the manufacture of gasoline, plastics, etc.


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Feb 126:05 PM

3. No rotation around a carbon-carbon double bond4. Alkenes are non-polar5. Alkenes are unsaturated 6. Structural isomers exist for all alkenes larger than propene7. LDFs only 8. As the number of carbons increase, boiling and melting points increase also


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Feb 126:07 PM

Alkyne Properties1. As the number of carbons increase, boiling and melting points increase also.

2. Alkynes are non-polar and are soluble in non-polar solvents only.

3. LDFs only


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Feb 126:09 PM

• 4. Alkynes are unsaturated

• 7. React in addition and hydrogenation reactions

• 5. No rotation around carbon-carbon triple bond.

• 6. Structural isomers exist for alkynes larger than propyne


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Apr 123:01 PM

PHYSICAL PROPERTIES OF CYCLOALKANES AND CYCLOALKENES

Cycloalkanes (and cycloalkenes) have higher boiling points and densities than their corresponding alkane (alkene) with the same number of carbons because of their more compact structure.ie: cyclopentane will have a higher boiling point than pentane.

Carbon Range Boiling point State

C1 C4 164 to 0.5 Gas

C5 C16 30 to 375 Liquid

C17 > 375 to 515 Wax like Solid


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Apr 123:02 PM

QUESTION:1. Construct a table, a) list alkene names, boiling points and # of electrons.

Alkenes Boiling Point # of electrons

Ethene 103.9 16

Propene 47.0 24

1butene 6.3 32

1pentene 30.0 40


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Feb 126:12 PM

b) list alkyne names, boiling points and # of electrons.

Alkynes Boiling Point # of electrons

Ethyne 81.8 14

Propyne 23.3 22

1butyne 8.6 30

1pentyne 40.0 38


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Feb 126:12 PM

c) For the homologous group with two carbons, listing boiling point and # of electrons.

compounds Boiling Point # of electrons

Ethane 88.5 18

Ethene 103.9 16

Ethyne 81.8 14


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Feb 126:17 PM

2.a) Which would you predict to have the lower boiling point and why?

Would predict ethyne having the lowest boiling point since it has the lowest number of electrons therefore the lowest LDF.


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Apr 123:19 PM

b) Suggest a reason why it does not.Another factor that affects the strength of LDF is the shape of the molecule. The closer the molecules can get together, the stronger the LDF will be. Ethyne C 2H2 is a linear molecule about each carbon.H C = C H

Ethene is trigonal planar about each carbon.

Ethane is tetrahedral about each carbon


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May 511:40 AM

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2202 2 alkenes and alkynes 2017...

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