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Organic Chemistry Lec > Module 5: ISOMERISM AND CHIRALITY > Flashcards

Module 5: ISOMERISM AND CHIRALITY Flashcards

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1
Q

Are compounds having the “same numbers and kinds of atoms” but “differ” in the way the atoms are “arranged”?

A

Isomers

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2
Q

Different bond patterns

A

Structural or Constitutional Isomers

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3
Q

Same bond patterns

A

Stereoisomers

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3
Q

Interconvertible by single bond rotation

A

Conformers (Rotamers)

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3
Q

The higher the number of carbons, _____________

A

the more constitutional isomers

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4
Q

Boiling point
= 78.4 degrees C

A

Ethanol

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4
Q

Not interconvertible by bond rotation

A

Configurational Isomers

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5
Q

Different carbon skeletons

A

Skeletal

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5
Q

“Different CONNECTIVITY”

A

Constitutional (Structural) Isomers

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6
Q

Different functional groups

A

Functional

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6
Q

Different position of functional groups

A

Positional

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7
Q

Boiling point
= -23 degrees C

A

Dimethyl Ether

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8
Q

In the plane of the page

A

Solid line

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8
Q

Comes “forwards” out of the plane of the page; [in front]
- points towards the viewer

A

Wedge line

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8
Q

Goes “backward” out of the plane of the page; [behind]

A

Dashed line

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8
Q

SAME CONNECTIVITY

A

Stereoisomers

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8
Q

The branch of chemistry concerned with the three-dimensional structures of molecules.

A

Stereochemistry

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8
Q

Different arrangements due to rotation around a SINGLE BOND

A

Conformers/ Rotamers

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8
Q

Same molecular formula and constitution but different spatial (3D) arrangement of atoms

A

Stereoisomers

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9
Q

[Projections]
= View from the side
= You can see the front and the back

A

Sawhorse projection

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10
Q

[Conformations of Ethane]

– The highest-energy, least stable conformation
– six C–H bonds are as close as possible

A

Eclipsed (1%)

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10
Q

[Projections]
= View from the front
= You can see the front and the back

A

Newman projection

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10
Q

[Conformations of Ethane]

– The lowest-energy, most stable conformation
– all six C–H bonds are as far away from one another as possible

A

Staggered (99%)

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10
Q

[Conformations of Ethane]

  • An angle equal to 60 degrees
A

Dihedral angle or Torsional angle

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10
Q

[Conformations of Butane]

  • Methyl groups are farthest apart
  • magkahiwalay
A

Anti

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11
Q

[Conformations of Butane]

  • Methyl groups experience a _______ interaction
  • Magkatabi
A

Gauche

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11
Q

[Conformations of Butane]

REPULSION AS A RESULT OF TRYING TO OCCUPY THE SAME SPACE

A

STERIC STRAIN

11
Q
  • Lack of rotation in C=C bonds
  • For disubstituted alkenes
  • Example: but-2-ene
A

Geometric (Cis-Trans) Isomers

12
Q

cis-but-2-ene

A

Geometric (Cis) Isomers

13
Q

trans-but-2-ene

A

Geometric (Trans) Isomers

13
Q

Geometric Isomers on the same side

A

Geometric (Cis) Isomers

13
Q

Geometric Isomers on different sides

A

Geometric (Trans) Isomers

13
Q

When two identical groups are connected to the same position, there cannot be cis-trans isomerism.

(True or False)

A

True

13
Q

1,1-dichloroprop-1-ene

(Isomeric or Not)

A

NOT ISOMERIC

13
Q

Involved in metabolism

A

Aconitic acid

13
Q

Which of the following is less stable?
cis-but-2-ene or trans-but-2-ene?

A

cis-but-2-ene

13
Q

interconversion of cis and trans alkene isomers is possible by using a?

A

strong acid catalyst

13
Q

= More polar
= Higher boiling point
= More beneficial to health

A

Cis

13
Q

= less polar
= lower boiling point
= less beneficial and harmful to health

A

Trans

14
Q

Cis is less stable than Trans because?

A

Groups are on the same side and are close to each other resulting in a “steric strain”

14
Q
  • “Chemistry concerned with 3D structures”
  • Focus on “chirality” (ky-ral-i-tee), or handedness (Greek cheir, meaning “hand”)
A

Stereochemistry

14
Q

Any object can be viewed in a mirror, revealing its mirror image.

A

Chirality

14
Q

[Chirality]

– The mirror image is identical to the actual object.
- Pantay

A

SUPERIMPOSABLE

15
Q

[Chirality]

– The object and its mirror image are different.
- Hindi Pantay

A

NONSUPERIMPOSABLE

15
Q
  • Finding Handedness in Molecules
    – The presence of a carbon atom bonded to
    four different groups
    → stereocenter, or chirality center or chiral carbon
A

CHIRALITY

15
Q

A carbon atom that is bonded into 4 unique groups

A

Stereocenter, or chirality center

16
Q
  • a plane that cuts through the middle of a molecule or other object so that one half of the object is a mirror image of the other half.
A
  • Plane of symmetry
16
Q

A molecule is “not chiral (achiral)” if it contains a plane of symmetry.

(True or False)

A

True

16
Q

Means Pantay or of Equal side when split in half

A

Symmetrical or Symmetry

17
Q
  • Ability to rotate a beam of plane-polarized
    light
  • Some optically active molecules rotate plane-polarized light
A

Optical Activity

17
Q

– Measures the amount of rotation

A

Polarimeter

18
Q
  • Some optically active molecules rotate plane-polarized light
    – to the right (clockwise)
A

→ Dextrorotatory (+)

18
Q
  • Some optically active molecules rotate plane-polarized light
    – to the left (counterclockwise)
A

→ Levorotatory (-)

19
Q
  • A.k.a. racemic (rah-see-mic) mixtures
  • 50:50 mixture of enantiomers
A

Racemetes

20
Q

Maximum number of stereoisomers = 2n
– Where n = number of chirality centers

A

Chirality Centers and Stereoisomers

20
Q
  • Stereoisomers that are nonsuperimposable mirror image
A

Enantiomers

20
Q
  • Stereoisomers that are NOT mirror images of each other
A

Diastereomers

21
Q
  • achiral Compounds, yet contain stereocenters
A

Meso Compounds

21
Q
  • Objects that are “not superimposable” on their mirror images are called “chiral objects.”
A

Chirality

21
Q

– The most common source of molecular chirality is the presence of a carbon atom bearing “four different groups.”
– Chiral center, stereocenter, stereogenic center, asymmetric center, CHIRAL CARBON

A

CHIRALITY CENTER

21
Q

sold under the trade name Darvon, is an “analgesic (painkiller)” and “antitussive (cough suppressant)”

A

Propoxyphene

22
Q

When a compound is chiral, it will have one non-superimposable mirror image, called its _____________ (from the Greek word meaning
“opposite”)

A

Enantiomers

22
Q

[Chirality in Nature]

  • a commonly prescribed medication
    sold under the trade name Prozac.
A

Fluoxetine

22
Q

[Chirality in Nature]

  • is an extraordinarily effective antidepressant, but it has no activity against migraine.
A

Racemic fluoxetine

23
Q

[Chirality in Nature]

  • works remarkably well in preventing migraine and is now undergoing clinical evaluation.
A

pure S enantiomer

Organic Chemistry Lec (5 decks)

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