paper 2 mistakes Flashcards

1
Q

which compound is used as a standard for NMR chemical shifts

A

Si(CH3)4

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2
Q

what do nucleophiles react with

A

electron pair acceptor (centre of electron deficiency)

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3
Q

markoffnikoffs rule

A

hydrogen more likely to bond to the carbon with the greatest number of hydrogens

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4
Q

structeral isomer

A

same molecular formula different structeral formula

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5
Q

amino acid + acyl chloride

A

N group becomes amide

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6
Q

how to turn a ketone into an ester

A

oxidise to carboxylic acid
add alchol

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7
Q

evidence for delocalised model

A

c-c and c=c different lenghts, X Ray differaction shows benzene is a regualr hexagon
^H hydrogenation less exothermic than expected, bonds more stable than alkenes
benzine didnt react with hydrogen hallide, bromine, H2SO4, no double bonds, cannot undergo electrophilic addition

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8
Q

deloaclised model of benzene

A

each C has 3 pi bonds, 120 degrees
leaves a spare electron in 2p orbital
2p orbitals overlap, above and below ring forming pi bonds
electrons are delocalised

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9
Q

why do CFSs reahc stratosphere

A

high bond enthalpies so not broken down in lower atmosphere, broekn down by UV in stratosphere

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10
Q

break down of ozone by CFC CCl3F

A

on post it note

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11
Q

what is phenol and what does this mean

A

weak acid
reacts with NaOH but not NA2CO3

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12
Q

when phenol reacts with Br2

A

Br2 decolourised and white ppt- no catalyst

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13
Q

2, 4 groups

A

electron donating
OH NH2
increase electron density

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14
Q

3,5 groups

A

electron withdrawing
NO2
decreases electron density

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15
Q

synthesis of an organic liquid

A

once reaction complete, pour mixtures into seperating funnel
neutralise any excess acid using sodium carbonate, stops bubbling when neutral
allow 2 layers to settle
use density to establish layers, or add water and aq layer will get bigger
collect wanted layer
add drying agent (anhydrous CaCl2)
distil dried product and collect fraction that comes off at stated bioling point

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16
Q

purity of organic liquid

A

boiling point should match known data, impurities widen narrow bp range
run TLC, measure Rf compare to known data/ run for pure sample
run NMR/ mass spec compare to database of known pure compounds

17
Q

synthesis of organic solid

A

purify by recrystlaisation
dissolve in min vol of hot solvent
cool in ice to recrysatlise (impurities stay in solution)
filter using Buchner funnel
wash with cold solvent
dry

18
Q

purity of organic solid

A

measure mp, compare to data values
should melt sharply over narrow range
TLC

19
Q

how to make primary amine

A

haloalkanes with excess ammonia in ehtnaol

20
Q

test for phenols

A

test acidity
add Na2CO3-no effervescence

21
Q

explain relative resistance to chloronation of benzene vs alkene

A

alkene: electrons are localised
electron density higher
more susceptible to electrophilic attack
polarises Cl2 more
benzene: deloaclised
electron density lower
cannot polarise

22
Q

other products formed when carboxylioc acid + SOCl2

A

acyl chloride, SO2, HCl

23
Q

explain the use of two denatured compounds in NMR spectroscopy

A

CDCl3 used as solvent
D2O used to identify OH and NH protons