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Chem Unit 4 > 4.8 Organic Synthesis 5 > Flashcards

4.8 Organic Synthesis 5 Flashcards

1
Q

what factors might be considered when deciding on a synthesis route?

A

-type of rctn
-reagents
-atom economy
-byproducts
-conditions

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2
Q

what condition is req for alkanes to undergo free radical substitution with halogens?

A

is a photochemical rctn so the rct req ultraviolet light

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3
Q

what diff products can be produced when alkenes undergo electrophilic addition?

A

hydrogen halide->halogenoalkane
halogen->di-halogenoalkane
hydrogen-> alkane
steam->alcohol

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4
Q

name process in which alkenes can react to form polymers:

A

addition polymerisation

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5
Q

what reactant and conditions are req for a halogenoalkane to form a nitrile?

A

reactant: ethanolic KCN
conditions: warm, reflux setup

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6
Q

name the mechanism and products formed when halogenoalkanes react with ammonia

A

mechanism: nucleophilic sub
prod: amines

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7
Q

name 2 types of rctns bet halogenoalkanes and hydroxides. how can u influence which rctn will occur?

A

nucleophilic sub- prod alcohol, aq cond req
elimination - prod alkenes, anhydrous ethanolic cond req

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8
Q

how can alcohols react to form alkenes?

A

alcohols can undergo dehydration with conc sulfuric acid (catalyst) to form alkenes, this is an elimination rctn

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9
Q

what are the various products formed when alcohols react with acidified potassium dichromate(VI)?

A

primary alcohols are oxidised to aldehydes then to carboxylic acids
secondary alcohols are oxidised to ketones
tertiary alcohols do not undergo oxidation with acidified potassium dichromate(VI)

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10
Q

what are produced when alcohols react with carboxylic acids?

A

esters

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11
Q

reducing agent req for aldehydes and ketones to form alcohols

A

NaBH4 in water with methanol

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12
Q

reactants and mechanism for the formation of hydroxynitriles from aldehydes?

A

reactants: acidified KCN
nucleophilic addition

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13
Q

reducing agent req for carboxyliuc acids to form alcohols

A

LiAlH4

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14
Q

what are produced when nitriles undergo reduction with LiAlH4??

A

amines

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15
Q

reactants and mechanism for the formation of nitrobenzene from benzene

A

reactants: conc sulfuric acid and conc nitric acid
electrophilic substitution

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16
Q

how can arenes form benzoic acid?

A

benzoic acid is produced when side chains of arenes undergo oxidation. alkaline manganate (VII) followed by acidification is the most effective reagent

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17
Q

what are produced when phenol reacts with diazonium salts?

A

azo compounds

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18
Q

product obtained when phenol reacts with nitric acid?

A

nitrophenol

19
Q

different reactants req for acyl chlorides to produce primary amides, n-substituted amides, esters and carboxylic acids?

A

ammonia NH3->primary amide
amine->n-substituted amide
alcohol->ester
water->carboxylic acid

20
Q

give reactants and mechanism for production of a phenylketone from benzene

A

rectants: acyl chloride and AlCl3 catalyst
electrophilic substitution

21
Q

how can ethanoic acid be formed from chloroethane?

A

nucleophilic substitution with aqueous NaOH followed by oxidation with oxidising agent acidified potassium dichjriomate(VI)

chloroethane —NaOH(aq) refux–> ethanol —acidified potassium dichromate(VI)/H2SO4 refulx–> ethanoic acid

22
Q

how can 2-propylamine be formed from propene?

A

electrophilic addition with HBr followed by nucleophilic sub with NH3

propene —HBr(aq) RTP(room temp and pressure)–> 2-bromopropane —ethanolic NH3 heat–> 2-propylamine

23
Q

a synthetic route is chosen to prod an organic compound, in terms of reagents why might this route be favoured??

A

-reagents might be renewable
-reagents may have minimal safety concerns

24
Q

how are by-products linked to the selection of a particular synthetic route?

A

a synthetic route with less harmful by-products is preferred as there are fewer safety and environmental concerns. the process is more sustainable if the by-products can be used in another industry

25
Q

what condition req to ensure a primary alcohol forms a carboxylic acid upon oxidation?

A

rctn needs to be setup in reflux
reflux is the boiling setup with a vertical condenser that allows the vapours to return to the same mixture once they condense

26
Q

how can u separate an insoluble prod from a soln??

A

filtration
-filter paper in a funnel over a conical flask
-pour the mixture thru the funnel
-the insoluble prod is left in the filter paper

27
Q

describe how to carry out simple distillation?

A

heat a soln in a round bottomed flask using a bunsen burner the solvent evaporates then cools in the condenser the pure liquid is collected in a beaker

28
Q

describe how a solid can be purified by recrystallisation

A

1.add a minimum vol of hot solvent to impure solid until it dissolves
2.filter soln to remove any insoluble impurities
3.leave soln to slowly cool crystals will start to form
4.remove liquid containing soluble impurities from the crystals by filtering mixture under reduced pressure with a Büchner funnel
5. wash the crystals with ice cold solvent to remove any soluble impurities from the surface leave crystals to dry

29
Q

how can water soluble impurities be separated from an insoluble organic product??

A

once the reaction is complete pour mixture into a separating funnel and add water. shake funnel then leave mixture to settle two distinct layers will form since organic layer and aq layer will not mix. the tap on the separating funnel can then be opened and each layer can be run off separately

30
Q

difference between addition polymerisation and condensation polymerisation?

A

addition polymerisation is the process by which polymers are formed by addition of monomers with no by-products. condensation polymerisation usually involves 2 diff types of monomers (each w/ at least 2 functional grps) undergoing condensation resulting in formation of small molecules such as HCl, water or ammonia as a by-prod

31
Q

how are polyesters formed?

A

polyesters form when dicarboxylic acids react w/ diols in a condensation rctn

32
Q

how are polyamides formed??

A

polyamides form when dicarboxylic acids react w/ diamines in a condensation rctn

33
Q

which 2 monomers are used to make nylon-6,6?

A

1,6- diaminohexane
hexanedioic acid

34
Q

how is PET produced??

A

PET is formed from benzene-1,4-dicarboxylic acid and ethane-1,2-diol the 2 monomers react together and ester links form between them

35
Q

how can you determine the melting point of an organic solid??

A

1.pack a small sample of solid jnto a capillary tube place tube inside a heating element
2. increase temp of the heating element until sample turns to liquid
3.compare melting point of data book values to identify solid

36
Q

how can mp of a substance be used to evaluate its purity??

A

a pure substance will have an exact sharp mp an impure substance will melt over a range of temps

37
Q

how can NMR be used to identify a molecule??

A

NMR allows u to identify the diff fragments in the molecule which can then be used to predict the structure of the molecule

38
Q

how can a proton environment be identified using a proton NMR spectrum?

A

compare chem shift values of the peaks in an NMR spec to values in a data book

39
Q

on a proton NMR spec what does the ratio of the areas under the peaks indicate??

A

the relative number of protons in each environment

40
Q

what are equivalent protons??

A

protons in the same environment, may be on the same or diff carbons

41
Q

what is chromatography?

A

chromatography is a process used to separate a mixture into diff components, involves a mobile phase, where the molecules can move & a stationary phase where molecules can’t move

42
Q

how can tlc be used to separate mixtures?

A

-a glass plate has a thin layer of silica/ alumina fixed to it acting as the stationary phase,
-mixture to be separated is dotted on a baseline near the bottom of the plate,
-plate then put in solvent, mobile phase moves up plate, mixture seperates depending on how soluble it is in the solvent,
-distance each component travels up theplate can be measured & an Rf value can be calculated to help identify which components are present

43
Q

what is an Rf value & how can it be calculated?

A

the Rf value is the retention factor, identifies particular components
Rf= distance moved by component/ distance moved by solvent

44
Q

how can HPLC be used to find the composition of mixture??

A

-a vertical column packed with a solid acts as the stationary phase,
-solvent containing the mixture beign analysed is then added as the mobile phase,
-mixture washes thru column components separate out depending on how soluble they are in mobile phase,
-time it takes for component to pass thru column is retention time can be used for identification

Chem Unit 4 (8 decks)

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