organic 4&5 Flashcards by Martha Robbins

why different alkanes in crude oil can be separated buy fractional distillation

different boiling point due to different chain lengths? strength of IM forces

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reaction 1 = ethene + HBr at room temp =

CH3CH2Br

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what reagent to convert ethene to ethanol

steam and acid

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Deduce structure of T ( C4H10O)
U(C4H8O)
and V (C6H12O2)

T= butan-2-ol = secondary alcohol because it was oxidised to a ketone 
U= butane = gives orange ppt with 2,4DPH and does not give ppt with feelings 
V= 1-methyl propyl ethanoate = ester as alcohols react with acyl chlorides to produce esters

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compare bromination of phenol with bromination of benzene

both electrophilic substitution
no need of a halogen carrier with phenol
oxygens lone pair of e- interacts with the benzene ring of delocalised e- so electrophilic attach more likely
tri-subsitution with phenol. mono with bromine
bromination of phenol requires bromine in aqueous solution but benzene required liquid bromine

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mechanism between electrophile NO2+ and phenol to produce 4-nitophenol

arrow from circle of ring to NO2+
NO2 and H on 4th carbon and positive charge
4-nitrophenol and H+

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what is the mass of 4-nitrophenol produced from 0.94g of phenol if the yield of this isomer if 15%

0.21

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deduce two monomers to produce this polyamide

HOOC-(CH2)4-COOH
and
H2N-(CH2)4-NH2

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deduce single monomer to produce the polyamide

H2N-(CH2)4-COOH

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how separate samples of two enantiomers could be distinguished

rotate plane of polarised light equally in opposite directions

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explain the trend in reactivity of primary chloro-, bromo- and iodoalkanes with aq OH- ions

reactivity increases down G7 because C-X bond enthalpy decreases

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mechanism for aq NaOH with 1-bromoethane to produce ethanol

arrow from OH- lone pair to C
C(delta +) Br(delta -)
intermediate [OH——-C——-Br]-
ethanol+ Br-

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give reagents used to test for bromide ions in mixture

nitric acid
silver nitrate solution
cream ppt

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why ethene has a lower boiling temperature than ethanol

ethanol has HB and LDF
ethene only has LDF
more energy required to break HB in ethanol

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balance Cr2O7 2- + H+ + e- = Cr3+ + H20

Cr2O7 2- + 14H+ + 6e- = 2Cr3+ + 7H20

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Cr2O7 2- + H+ + e- = Cr3+ + H20

colours

Cr2O7 2- + H+ + e- = Cr3+ + H20

orange colourless. green colourless

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state how granules prevent bumping

prevent uncontrolled boiling by providing a surface to allow smaller bubbles to form

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why using distillation Not reflux is not an efficient way to produce ethnic acid from ethanol

ethanol would be oxidised to ethanal because ethanal has low boiling temp

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how many structural isomers are there with molecular formulas C5H12

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how many sigma and pi bonds are there in one molecule of cyclohexane

sigma= 16 
pi= 1

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benzene to phenylethene

+aluminium chloride +heat (acylation of benzene = ethanol chloride
A= phenylethanone
+LiALH4 in dry ether (reduce)
B= phenylethanol
dehydrate B with concentrated phosphoric acid

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give one advantage and one disadvantage of disposal of polystyrene by incineration

advantage = avoids landfill 
disadvantage = releases toxic fumes

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name compound responsible for peak at 0ppm

due to Tetramethylsilane

so chemical shifts can be compared

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identify proton environment that causes chemical shift at 3.8ppm

singlet = non neighbouring hydrogen atoms

3 hydrogen atomes in environnent

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mechanism for reaction of methyl cinnamate and bromine

double bond to Br-Br Br(d+)---Br(d-) split + on where double bond was arrow from lone pari on Br to +

identify amino acids present and resin for lack of third spot

serine and methionine | may have same Rf value as either serene or mathinone

why do amino acids have different solubilitys

different solubility to mobile phase | different solubility to stationary phase

Grignard reagent propanal = ?

2-methylpentan-3-ol

describe a grind reagent

nucleophile | reducing agent

stare added to grinyard in a

propane

ethanal to lactic acid

``` +HCN nucleophilic addition CH3CHO + HCN = CH3CH(OH)CN +HCl (strong acid) heat under reflux hydrolysis CH3CH(OH)CN + 2H2O+ H+ = CH3CH(OH)COOH + NH4+ ```

type of polymerisation

condensation polymerisation

mechanism for reaction of chloroalkane and benzene catalysed by AlCl3

``` arrow from ring to CH3CH2+ + in ring and H and CH2CH3 attached arrow from H to + benzene--CH2CH3 + H+ AlCL4- + H+ = AlCl3 + HCl ```

explain whether phenol is likely to be less or more reactive than benzene with chloroalkane

phenol = more reactive lone pair on oxygen incorporated into benzene ring increases electron density of ring makes phenol more susceptible to electrophilic attack

why different compounds have different retention Times in gas chromatography

retention time depends on attraction to stationary phase | greater attraction = greater retention time

explain changes in mass of X and Y if the oxygen gas was not dry

mass of X would increase as solid X would also absorb H2O in oxygen mass of Y would NOT change as H2O has already been absorbed by X

3.36g of D produced 0.72g of water and 5.28g of CO2 and 0.56g of nitrogen find empirical formular

H = H20= 0.72g/18 = 0.04 moles x 2 = 0.08 moles of H C= CO2=5.28/12+16+16 = 0.12 moles N= N2=0.56/14+14 = 0.02 x 2 = 0.04 moles of N O= 3.36-(12x0.12+1x0.08+14x0.04)= 1.28/16 = 0.08 moles of O divide all moles by 0.04 2:3:1:2 C3H2NO2

what is the reaction when ethane and chlorine react in UV light

D | free radical sub

name of alkane

B | 4 ethyl 3 methylheptane

which has moleular formula C6H10?

systematic name of alkene

C | 2,3-dimethylbut-1-ene

number of molecules in 70g of but-1-ene

70/56 = 1.25 | 1.25 x avogadros = 7.525x10^23

which is hydrolysed to form methanol as a product? which compound produces carbon dioxide when it reacts with aq sodium hydrogen carbonate?

(b) Q | (a) P

complete equation for the reaction of phenol with excess bromine water

phenol + 3Br2 = 2,4,6bromo-phenol + 3HBr

what is the mass of 4nitrophenol produced from 0.94g of phenol if yield of isomer is 15%

(b) 0.21

reaction of ethane and chlorine in UV radiation produces chloroethane reaction is a

(D) substitution

black smoke produced from incomplete combustion of alkane fuel is

(A)carbon particles

reaction of hexane is

(D)reforming

molecular formula of decalin is

which alcohol would be oxidised under reflux to produce this carboxylic acid

(B) | 2-methylpropan-1-ol

which of these formula represents a noncyclic saturated hydrocarbon

(D) | C6H14

calculate percentage by mass of carbon in phenylethene

phenylethene - 104 carbon - 96 96/104 x100 = 92%

which reagent could produce a diol from phenylethene

(B) acidified potassium manganate

calculate mass of carbon in 2.34g of methyl cinnamate

120/162 = 0.74 x 2.34 = 1.73g

dudcuce the number of optical isomers of the addition product that can exist

add dipoles to Grignard reagent

C (d-) | MgBr (d+)

sample of xylene had a mass of 0.271g at temp 165 degree C and pressure 118kPa the sample had a volume of 70.5cm3 calculate molar mass of sample

``` pV = nRT T= 438K P =118000Pa V= 7.05x10-5 m^3 R=8.31 ``` find n = 2.28x10-3 moles RFM = mass/moles = 0.271/ 2.28x10-3 = 119 gmol-1

formula of D

C6H4N2O4 Mr= 168 (12x6) + (4) + (2x12) + (16x4) = 168

give formula at peak m/z= 76

C6H4+

13C NMR spec of compound D has 4 peaks identify structure of D justify by labelling all carbon environments in structures in c

1,3 di-nitrobenzene

reasons for steps 2(cool mixture) 3 (anti bumping granules) and 4 (heat under reflux)

cool mixture = reaction is very exothermic anti bumping granules = promote formation of small bubbles heat under reflux = prevent the loss of any volatile substances

identify 3 errors in reflux

water is flowing the wrong was out the condenser - doesn't fill up with water gap between condenser and the flask - gas will escape stopper on the condenser - there will be a build up of pressure if gap between condenser and flask is closed

why the brown vapour forms

bromine | bromide ions oxidised by concentrated sulphuric acid

state position of aq layer in sperating funnel at start of step 6

aqueous layer Is on the top because H2o has lower density than 1-bromombutane

reasons for step 8,9 and 10

``` 8 = NHCO3 reacts with H+ ions in the picture 9 = tap opened to release CO2 10 = anhydrous sodium sulphate is added to remove water ```

sutible temp range to which to collect pure 1-bromobutane

100-105 degrees

vol of bromobutane is 12cm3 | calculate number of molecules of 1-bromombutane produced

``` mass = density x vol = 12 x 1.27 = 15.24g moles = 15.24/136.9 = 0.11132 moles molecules = 0.11132 x (6.02x1023) = 6.7x10^22 ```

organic 4&5 Flashcards

(67 cards)