Stereochemistry and Isomerism (3) - conformation Flashcards

1
Q

different spatial arrangement

A

rotation around bonding

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2
Q

how conformation is made

A

made different by rotation of chemical bonds

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3
Q

staggered conformation

A

substituent located far from each other

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4
Q

eclipse conformation

A

substituents located in the same plane

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5
Q

stability of stagger vs eclipse

A

staggered - more stable - chemical bonds one from each other

due to chemical bonds - compose of e- - repel

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6
Q

Newman molecules projection - view

A

along axis of bond - placing circle in middle and perpendicular to bond and project molecule

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7
Q

example - Newman molecules projection - ethanol

A

determine from RHS

projected easily - allow derivation of dihedral angle

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8
Q

dihedral angle

A

angle between 2 bonds of substituent on adjacent atom

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9
Q

cyclohexane

A

not flat ring - in order have 109 degree 28’ bond angles

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10
Q

chair conformation example

A

diamond lattice - form chair cyclohexane building block

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11
Q

2 types of substiuents

A

axial - perpendicular to plane

equatorial - along the plane

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12
Q

rotation in cyclohexane - ring inversion

A

moves one side of plane up - forming boat formation

move other side of plane down

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13
Q

ring inversion

A

axial substituent become equatorial - vice versa

v. dynamic

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14
Q

monosubstituted cyclohexane

A

thermodynamic preference for equatorial substituted chair

- H atoms - v. close - repel

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15
Q

chair formation stability vs boat formation

A

chair formation - more stable - all the bonds are staggered

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16
Q

carbohydrates - naturally occurring

A

D-sugars - absolute configuration of stereogenic centre at bottom of fisher
L-sugar - L-fucose

17
Q

chemically not most stable molecule

A

hemi-acetal = one alcohol react to aldehyde

conversion from fisher structure to cycle structure straightforward

18
Q

sawhorse to chair form

A

in C1 - OH is above the plane therefore will be at equatorial
C2 on the equatorial - below axial - below plane