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Biochem Y1 > FoC : Organic Structures And Mechanisms > Flashcards

FoC : Organic Structures And Mechanisms Flashcards

1
Q

Definition: isomer

A

Compounds with the same molecular formula but different constitution, configuration and conformation

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2
Q

Definition: Constitutional isomers

A

Differences in the nature of sequence of atoms in a molecule (connectivity)

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3
Q

Definition: stereoisomer

A

Two or more compounds whose structure differ only I. The 3d arrangement of their constituent atoms. (Same constituency but fixed in different special arrangement)

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4
Q

Why is their stereo isomerism in alkenes (sp2 carbon)

A

Alkenes are planar
Double bond (pi and sigma)
No rotation as would break pi overlap

These are isolatable, separatable with different boiling points and optical properties

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5
Q

How is priority assigned in a stereoisomer

A

Atomic number
Oxidation level

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6
Q

Why is there steroisomerism in saturated carbons (sp3 carbons)

A

If 4 different groups are attached to a carbon it’s chiral
2 non superimposable images can be created
These are a pair of enantiomers

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7
Q

priority sequencing of sp3 carbon atoms

A

lowest priority at the back(dashed line)
clockwise then R
anticlockwise then S

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8
Q

how to measure optical activity

A

specific rotation = observed angle of rotation/ pathlength (dm) x density (gcm-3)

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9
Q

what is a meso isomer

A

no optical rotation due to internal compensation these are in molecules with 2 identical chiral centres

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10
Q

what are diasterisomers

A

stereoisomers which are not enantiomers

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11
Q

whats the maximum number of stereoisomers that you can get in a molecule

A

2 to the power of n
where n is the number of chiral centres

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12
Q

what are confermers

A

inseparable isomers thst have different spacial arrangements as a result of free rotation about a single bond

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13
Q

what is the newman projection of molecules

A

front view of molecule

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14
Q

what are the types of conformer

A

ecliped conformer and staggered conformer

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15
Q

what type of conformer is more stabled

A

staggered conformers as they are 12kJmol-1 more stabled then eclipsed

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16
Q

what is tortional strain

A

the energy barrier to rotation

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17
Q

what is the origin of tortional strain

A

repulsion between electron clouds

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18
Q

what are the types of conformers when there is a priority group on each carbon

A

synperiplanar (ecliped with the priority groups in the same place), synclinal (staggered with both at similar place) , antiperiplanar (staggered priority groups opposite sides) , anticlinal ( eclipsed on opposite sides)

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19
Q

what is the energy levels of each orientationss

A

antiperiplanar, synclinal, anticlinal and synperiplanar (fronm lowest to highest)

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20
Q

what are atropisomers

A

enantiomers that result from restricted rotation around a simple bonds

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21
Q

what is a gauche conformation

A

where the angleis more then 0 degrees but less than 120 degrees

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22
Q

why is cyclopropane astrong electrophile

A

it can’t adopt a different conformation other then flat and is therefore high energy

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23
Q

why do some cyclo compounds adopt alternative shaped structures

A

to minimise tortional strain

24
Q

what is the signifivcance of chair and boat

A

they are both formationsthat cyclohexane can tak to minimise tortional strain

25
Q

what does boat conformation look like

A

little chem book reference

26
Q

what does chair conformation look like

A

reference chem book

27
Q

what is a level one functional group

A

one bond to a heteroatom from carbon

28
Q

what are the level one functional groups

A

halogens, alcohols and thiols, ethers, thioethers, epoxide, peroxides, amines

29
Q

what is an epoxide

A

a cyclic molecule with 2 carbons joined together that are also joined to the same oxygen

30
Q

what is a peroxide

A

2 O bonded together with alkyles on ether side

31
Q

what is a thiether

A

an ether but instead of an O its a S

32
Q

what are the level 2 functional groups

A

multipul halogens, ketones, aldehydes, hydrates, hemiacetal, acetal, imine, oximine

33
Q

what is a hydrate

A

a carbon with 2 alcohol groups

34
Q

what is a hemiacetal

A

a carbon with one alc and one ether

35
Q

what is an acetal

A

a carbon with 2 ethers

36
Q

what is an imine

A

a secondary carbon with a double bonded nitrogen that has an r group

37
Q

what is an oxime

A

a secondary carbon with double bonded nitrogen which is bonded to an alcohol

38
Q

what are the level 3 functional groups

A

halogens, carboxylic acids, esters, anhydrides, acid chlorides, amide, nitrile

39
Q

what are the level 4 functional groups

A

carbonate, carbamate, urea and isocyanate

40
Q

what is a carbonate

A

a carbon bonded to a double bonded O with 2 ether groups

41
Q

whats a carbamate

A

a carbon with double bonded O with 1 ether and 1 amine

42
Q

what is urea

A

a carbon with a doubled bonded O and 2 amine groups

43
Q

what is an isocynate

A

carbon with double bonded O and double bonded N

44
Q

which functional level is most readily oxidised

A

4

45
Q

what is oxidation

A

increase in functional group level

46
Q

what is reduction

A

decrease in functional group level

47
Q

what is an inductive effect

A

the way electronegative atoms polarize electron density in a single bond

48
Q

what is heterolytic bond cleavage

A

the movement of 2 electrons to the more electronegatice atom

49
Q

what is homolytic bond cleavage

A

the movement of one elctron to 2 different atoms from the single bond (shown with fish hook arrows) creates radicals

50
Q

what is mesomeric effect

A

the movement of e- density froom either double bond or lone pair by resonance

51
Q

what is hyperconjugation

A

alkyl groups will donate electrons to another carbon due to the partial overlap of empty carbocation orbital

52
Q

reaction priority rules

A

e- flow must start from an electron rich site
move towards an electron poor site
the flow must end somewhere good (not have five bonds to a carbon and ideally at an electronegative atom)
charge is concerved (if there’s a negative charge at the start there must be at the end)

53
Q

priority of electron rich sites starting point

A

negative charge
lone pair
double bond
single bond

54
Q

where the starting point goes to

A

positive charge on carbon or H+
atom next to an otherwise positive ion
somewhere that leads to a positive charge
partially positive charge

55
Q

what is a base

A

electrophile will react with a postve carbon or partially positive carbon

56
Q

what is a nucleophile

A

acid a positive hydrogen or partially positive hydrogen will react with a base

Biochem Y1 (11 decks)

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