6th Flashcards

1
Q

🌷to predict how smt might react
or if they have reacted we should look at

A

movement of electrons

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2
Q

what is a resonance arrow used for

A

shows the interconversion between 2 different representations of the same molecule

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3
Q

if we draw an arrow from somewhere that place should then have

A

a positive charge

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4
Q

if we draw an arrow to somewhere that place should have a

A

negative charge

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5
Q

H+ number of electrons

A

0
this is a proton

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6
Q

electrons can be shared from a lone pair or a🌷

A

bond
arrow should be drawn through the C that is making the bond
the C would then have a +

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7
Q

species giving the electrons is called a🌷

A

nucleophile
attracted to positive

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8
Q

🌷species that receive the electrons

A

electrophile
attracted to the negative

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9
Q

the higher the enthalpy of hydrogenation🌷

A

the less stable it is
more energy released

energy released when smt is heated up

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10
Q

when double bonds and single bonds alternate

A

conjugated alkenes

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11
Q

what is a property of conjugated alkenes🌷

A

they are more stable than expected
they release less energy than expected

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12
Q

different between conjugated and non conjugated alkenes🌷

A

conjugated: pi orbitals overlap and interact + overlap allowing greater stability

non conjugated: pi orbitals are not close enough to interact + overlap and increase stability

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13
Q

how come they both have pi orbitals??

A

alkenes : sp2 hybridised meaning one 1 orbital is not hybridised and is free

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14
Q

orbitals

A

regions of space where electrons are likely to be found

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15
Q

nodes

A

areas of space where the probability of finding an electron is 0

points of 0 electron density

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16
Q

🌷the more conjugated a system is…

A

the less nodes there are
less nodes = lower energy
lower energy = more stable

17
Q

particle in the box

A

3 nodes = highest energy empty
2 nodes = LUMO - lowest unoccupied molecular orbital) empty
1 node = HOMO - highest occupied molecular orbital) full
0 nodes = lowest energy full

18
Q

in conjugated systems electrons can be🌷

A

shared throughout 1 extended molecular orbital

FORMS RESONANCE STRUCTURES

19
Q

what do resonance structures help us understand🌷

A

how organic molecules may react

20
Q

🌷resonance can also be called the

A

mesomeric effect

21
Q

🌷what is the mesomeric effect

A

electrons being moved within a molecule

can influence: acidity, basicity + movement of charge

effects the behaviour of molecules

22
Q

conjugated nucleophilic addition // michael addition

A

when u conjugate a molecule
u see it can react in a way u didn’t think it would before.
nucleophile attacking end carbon due to double bond electron density moving + leaving it with a + charge.

23
Q

🌷conjugation can occur with bonds and

A

lone pairs!!!

24
Q

whats so great about benzene + conjugation

A

resonance in benzene leads to greater stability than in linear conjugated alkenes.

this is bc p orbitals involved in pi bonds are aligned perfectly for max conjugation

25
Q

what are the 4 conditions to making smt aromatic

A
  • flat
  • conjugated pi electrons
  • cyclic
  • HUCKELS RULE ( 4n+2 electron number)
26
Q

more on HUCKELS RULE
read this

A

benzene = 6 electrons
4n+2
if n= 1 the answer is 6
this means benzene fits it.

n is in integer that when combined with the equation, should give the total number of pi electrons in the molecule.

27
Q

difference between aromatic and non aromatic molecules🌷

A

aromatic = much more stable

aromatic -> non aromatic = energy penalty

smt can react with non aromatic but will find it harder to react with aromatic as it’s far more stable.

28
Q

alkenes and aromatics are separate things!!
🌷
what goes between the two

A

conjugated alkenes

29
Q

what about aromatic molecules with electron donating groups bonded to it.
eg: phenol🌷

A

lone pairs on the O can make the pi system more electron rich.

this attracts more electrophiles