IB Chemistry on Structural Isomers for Organic Molecules

http://lawrencekok.blogspot.com

Prepared by Lawrence Kok

Tutorial on Structural Isomers of Organic Molecules.

http://lawrencekok.blogspot.com/


Isomerism

Isomers – Organic molecules with same molecular formula but different arrangement of atoms

Two types of Isomerism

Structural Isomerism• Same molecular formula• Different structural formula• Different arrangement of atoms

Hydrocarbon Chain Isomer• Different hydrocarbon chain skeleton

Stereoisomerism• Same molecular formula• Same structural formula• Different spatial arrangement of atoms

Positional Chain Isomer• Different

functional group position

Functional Group Isomer• Different functional group

Geometric Isomers

Optical Isomers

Cis IsomersAtoms are located

on the same side

Trans IsomersAtoms are located

on the different side

CH3 -CH –CH2 –CH3

│ OH

CH3 -CH –CH –CH3 │ OH

CH3 –CH2–CH2 – O – CH3


| OH

CH3 - CH – CH2 │ | CH3 OH


│ OH


Structural Isomerism for C4H9OH• Same molecular formula

• Different structural formula• Different arrangement of atoms

Hydrocarbon Chain Isomer• Different

hydrocarbon chain skeleton

CH3 - CH – CH2 – OH │ CH3

CH3 │ CH3 - C – OH │ CH3

CH3 –CH2 –CH2 –CH3

│ OH

Butan – 1-ol 2- Methylpropan-1-ol

2- Methylpropan-2-ol

Structural Isomerism






Positional Chain Isomer• Different functional group position


│ OH

CH3 –CH2 –CH –CH3 │ OH


CH3 │ CH3 - C – OH │ CH3


│ OH



Butan – 1-ol Butan – 2- ol







Positional Chain Isomer• Different functional group position



│ OH



CH3 │ CH3 - C – OH │ CH3


│ OH

CH3 –CH2–CH2 – O – CH3

CH3 –CH2 – O – CH2 -CH3



Butan – 1-ol Butan – 2- ol

Butan – 1-olMethoxypropane Ethoxyethane



│ OH

Structural Isomers for C4H9OH – All have same Molecular Formula but different Structural Formula




│ OH



CH3 │ CH3 - C – OH │ CH3

CH3 –CH2–CH2 –O – CH3

CH3 –CH2 –O– CH2 -CH3

C4H9OH C4H9OHC4H9OH

C4H9OH

C4H9OH C4H9OH





│ OH



CH3 │ CH3 - C – OH │ CH3



C4H9OH C4H9OHC4H9OH

C4H9OH

C4H9OH C4H9OH

Structural Isomers for C4H9Br – All have same Molecular Formula but different Structural Formula


│ Br

CH3 –CH2 –CH –CH3 │ Br

CH3 - CH – CH2 – Br │ CH3

CH3 │ CH3 - C – Br │ CH3

C4H9Br C4H9Br C4H9Br

C4H9Br

H │CH3 –CH2– C=O

O ║ CH3 – C– CH3





│ OH



CH3 │ CH3 - C – OH │ CH3



C4H9OH C4H9OHC4H9OH

C4H9OH

C4H9OH C4H9OH

Structural Isomers for C4H9Br – All have same Molecular Formula but different Structural Formula


│ Br

CH3 –CH2 –CH –CH3 │ Br

CH3 - CH – CH2 – Br │ CH3

CH3 │ CH3 - C – Br │ CH3 Structural Isomers for C3H6O – All have same Molecular Formula but different Structural Formula

OH │CH3 –CH = C-H

OH │CH2 =CH - C-H2

CH3 – O – CH = CH2

C4H9Br C4H9Br C4H9Br

C4H9Br

C3H6O C3H6O C3H6O C3H6O C3H6O



Structural Isomers for C4H8

Structural Isomers for C4H10O




CH3 –CH = CH –CH3

CH2 = CH –CH2 –CH3


│ OH



CH3-CH–CH2–OH │ CH3

CH3 │ CH3 - C – OH │ CH3

CH3-CH2-CH2-O–CH3

CH3 -CH2 –O–CH2-CH3

CH3–CH–O–CH3

|

CH3

CH3 –C=CH2

| CH3

CH2 – CH2

| | CH2 - CH2




CH3 –CH = CH –CH3

CH2 = CH –CH2 –CH3


│ OH





Positional Chain Isomer• Different

functional group position


CH3-CH–CH2–OH │ CH3

CH3 │ CH3 - C – OH │ CH3

CH3-CH2-CH2-O–CH3

CH3 -CH2 –O–CH2-CH3

CH3–CH–O–CH3

|

CH3

CH3 –C=CH2

| CH3

CH2 – CH2

| | CH2 - CH2

Ether gpAlcohol gp Alcohol gp

Alkene gpAlkene gpAlkene gp Cycloalkane gp


Structural Isomers for C3H6O2



CH3 –CH2 –CH2 –C-H ║ O

CH3– CH – C-H | ║ CH3 O

CH3 –CH2 –C –CH3

║ O

CH2 =CH–CH2–CH2-OH CH3 -CH = CH –CH2-OH CH3 –CH2 -CH=CH-OH

CH3–CH2 -O- CH=CH2

CH3–CH =CH-O- CH3


CH3–CH2 –C-OH ║ O

CH3 –C- O-CH3

║ O

H-C-O-CH2-CH3

║ O

CH2- CH = CH | |OH OH

CH = CH–O–CH3

| OH

CH2 = C–O– CH3

| OH

CH2– CH-OH CH -OH


CH2- C =CH2

| |OH OH

CH =C –CH3

| |OH OH

CH2 = CH–O–CH2

| OH

HO-C=CH–CH3

| OH HO-CH-CH=CH2

| OH

CH3-O-CH2–C-H ║ O

OH |CH3-CH–C-H ║ O

OH |CH2-CH2–C-H ║ O


CH3 –CH2 –CH2 –C-H ║ O

CH3– CH – C-H | ║ CH3 O

CH3 –CH2 –C –CH3

║ O

CH2 =CH–CH2–CH2-OH CH3 -CH = CH –CH2-OH CH3 –CH2 -CH=CH-OH

CH3–CH2 -O- CH=CH2

CH3–CH =CH-O- CH3


CH3–CH2 –C-OH ║ O

CH3 –C- O-CH3

║ O

H-C-O-CH2-CH3

║ O

CH2- CH = CH | |OH OH

CH = CH–O–CH3

| OH

CH2 = C–O– CH3

| OH

CH2– CH-OH CH -OH


Aldehyde group

Ketone group

Alcohol + Alkene group

Ether + Alkene group

Carboxyl group

Ester group

Dialcohol + Alkene gpEther , Alkene + Alcohol gp

CH2- C =CH2

| |OH OH

CH =C –CH3

| |OH OH

CH2 = CH–O–CH2

| OH

HO-C=CH–CH3

| OH HO-CH-CH=CH2

| OH

CH3-O-CH2–C-H ║ O

OH |CH3-CH–C-H ║ O

OH |CH2-CH2–C-H ║ O

Aldehyde + Alcohol gp

Aldehyde + ether gp




CH3 –CH2–CH2–CH2-CH2-CH3



CH3 –CH–CH2–CH2-CH3

| CH3

CH3 –CH2–CH–CH2-CH3

| CH3

CH3

|CH3 –C-CH2-CH3

| CH3

CH3 –CH–CH -CH3

| | CH3 CH3


CH2 =CH–CH2-CH2-CH3

CH3-CH=CH-CH2-CH3

CH2 =C–CH2-CH3

| CH3 CH2=CH–CH-CH3

| CH3 CH3-CH=C-CH3

| CH3

CH3–CH- CH-CH3

CH2

CH2– CH- CH2-CH3

CH2

CH3

|CH2– C-CH3

CH2

CH2 – CH-CH3

| | CH2– CH2

C H2

CH2 CH2

| | CH2 –CH2

Alkene groupCycloalkane group


Structural Isomers for C5H11Br

CH3 –CH2–CH2–CH2-CH2 Br

CH3 –CH–CH2–CH2-Br

| CH3 CH3 –CH2–CH–CH2-Br

| CH3

CH3 -CH2–CH2–CH-CH3

| Br

CH3

|CH3–CH–CH-CH3

| Br CH3

|CH3–CH2–C-CH3

| Br

CH3 -CH2–CH–CH2-CH3

| Br

CH3–CH–CH-Br | | CH3 CH3

CH3

|CH3 –C-CH2-Br | CH3






| CH3


| Br

CH3

|CH3–CH–CH-CH3

| Br CH3

|CH3–CH2–C-CH3

| Br


| Br

CH3

|CH3 –CH2- C-Br | CH3

CH3

CH3

| |CH3– C- CH2

| Br

Are these different isomers too?


CH3







| CH3


| Br

CH3

|CH3–CH–CH-CH3

| Br CH3

|CH3–CH2–C-CH3

| Br


| Br

CH3

|CH3 –CH2- C-Br | CH3

CH3

CH3

| |CH3– C- CH2

| Br

Are these different isomers too?

No


CH3


same



CH3-CH2-CH2 –C-OH ║ O

CH3-CH – C-OH | ║ CH3 O

CH3 –C- O-CH2-CH3

║ O

H–C- O-CH2-CH2-CH3

║ O

CH3–CH2–C- O-CH3

║ O

CH2- CH2-CH = CH | |OH OH CH2- CH=CH- CH2

| |OH OH

CH2- CH-CH =CH2

| |OH OH

CH2- C =CH- CH3

| |OH OH

CH = C - CH2- CH3

| |OH OH

CH3- C = C - CH3

| | OH OH CH2 = C - CH- CH3

| | OH OH

CH3

|CH = C –CH2

| |OH OH CH2

║CH2 - C -CH2

| |OH OH

CH2 - CH-OH | |CH2 – CH-OH CH2 - CH-

OH | |HO-CH – CH2

Carboxyl gp

Ester gp

Cyclic dialcohol gp

Alkene + dialcohol gp



CH3-CH2-CH2 –C-OH ║ O

CH3-CH – C-OH | ║ CH3 O

CH3 –C- O-CH2-CH3

║ O

H–C- O-CH2-CH2-CH3

║ O

CH3–CH2–C- O-CH3

║ O

CH2- CH2-CH = CH | |OH OH CH2- CH=CH- CH2

| |OH OH

CH2- CH-CH =CH2

| |OH OH

CH2- C =CH- CH3

| |OH OH

CH = C - CH2- CH3

| |OH OH

CH3- C = C - CH3

| | OH OH CH2 = C - CH- CH3

| | OH OH

CH3

|CH = C –CH2

| |OH OH CH2

║CH2 - C -CH2

| |OH OH

OH |CH3-CH2-CH–C-H ║ O OH |CH3-CH-CH2–C-H ║ O

OH |CH2-CH2-CH2–C-H ║ O

OH |CH3-C – C-H | ║ CH3 O OH |CH2-CH – C-H | ║ CH3 O

CH3-O-CH2- CH2–C-H ║ O CH3CH2-O- CH2–C-H ║ O

CH3

|CH3-O- CH–C-H ║ O

CH = CH-CH2 –O–CH3

| OH CH = CH –O–CH2-CH3

| OH

CH2 = C-CH2 –O–CH3

| OH

CH2 –CH=CH –O–CH3

| OH

CH3–CH=CH–O–CH2

| OH

CH2 - CH-OH | |CH2 – CH-OH CH2 - CH-

OH | |HO-CH – CH2

Carboxyl gp

Ester gp

Cyclic dialcohol gp

Alkene + dialcohol gp

Alkene + Ether + Alcohol gp Aldehyde + ether gp Aldehyde + Alcohol gp

Any more isomers that you can draw?

Acknowledgements

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Thanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/

Prepared by Lawrence Kok

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Education

IB Chemistry on Structural Isomers for Organic Molecules