organic chem and analysis Flashcards by thiyara dhanapala

why was kekules model incorrect

benzene doesn’t decolourise bromine water
has a much less exothermic enthalpy change of hydrogenation than expected

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what are the conditions for nitration of benzene?

50ºC
concentrated acids
conc H2SO4 catalyst

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what are examples of a halogen carrier catalyst?

AlCl3
FeCl3
AlBr3
FeBr3

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What are examples of election donating groups?

OH
NH2
CH3

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What do election donating groups do?

Donate electron density into the pi system
Make it more reactive
Activate electrophile attack
Direct incoming electrophile to Carbon 2 and 4

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What is an example of an electron withdrawing group?

NO2

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What do election withdrawing groups do?

Remove electron density from the pi system
Make it less reactive
Deactivate electrophile attack
Direct incoming electrophiles to carbon 3

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What is carbon position 2/6 called

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What is carbon position 3/5 called

Meta

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What is carbon position 4 called?

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what are examples of stationary phase in TLC?

silica
alumina

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What is the stationary phase in gas chromatography?

Long coiled column, usually a non volatile liquid

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What is the mobile phase in gas chromatography?

Inert carrier gas
Eg helium, nitrogen

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what is the test for alkenes?

shake w orange bromine water
addition reaction takes place
decolourises bromine water

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what is the test for haloalkanes?

warm the haloalkane with NaOH in a mixture of ethanol and water
haloalkane will undergo nucleophilic substitution and release the halide ion into solution

acidify sample of halide ion w dilute nitric acid to remove carbonate ions
add silver nitrate
forms silver halide ppt

AgCl - white
AgBr - cream
AgI - yellow

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what is the test for alcohols?

1cm3 of alcohol in test tube
1cm3 of acidified potassium dichromate (oxidising agent)
add stopper to test tube and shake
place in 60ºC water bath for few mins
primary/ secondary= orange to green
tertiary= stays orange

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what is the test for carboxylic acids?

pH probe or dip end of glass rod in solution then on indicator paper- pH3
OR
1-2cm3 sodium carbonate added
gas bubbled produced
gas bulbbled into limewater
limewater turns cloudy
confirming gas is CO2

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what is the test for phenols?

shaken w bromine water
substitution reaction
decolourises bromine water
white ppt forms

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what are samples measured against in NMR and why?

TMS
produces single intense peak at far rhs
protons highly shielded
inert
non toxic

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which type of atoms need more energy to resonate in NMR?

more deshielded

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what are samples for NMR analysis dissolved in and why is this used?

deuterated solvents
all 1H replaced by deuterium D 2H
produces no signals in NMR

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in proton NMR, what does the ratio of the relevant areas under each peak represent?

ratio of how many protons responsible for each peak

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in proton NMR, how is the number of adjacent protons represented?

number of adjacent protons + 1
= number of sub peaks

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what can be used to test for carbonyl compounds

2,4- DNP

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what forms when 2,4- DNP is added to a carbonyl compound

orange ppt which can be used to identify specific carbonyl: recrystallise measure mp of ppt compare against known values

what can be used to test for aldehydes?

Tollen's reagent

how to make Tollens reagent

add aqueous ammonia to a solution of silver nitrate

what happens when an aldehyde is gently warmed w Tollen's regent

aldehyde oxidised to carboxylic acid colourless silver ions reduced to solid silver metal forms a silver mirror

what forms when a primary alcohol is distilled with an oxidising agent

aldehyde

what forms when a primary alcohol is refluxed with an oxidising agent

carboxylic acid

what forms when an aldehyde is distilled with an oxidising agent

carboxylic acid

what oxidising agent is used

acidified potassium dichromate K2Cr2O7 with H2SO4

what is the colour change when acidified potassium dichromate oxidises

orange to green

can ketones be further oxidised

no no readily available H strong oxidising agent wld be needed wld likely oxidise in a destructive way breaking a C-C bond

What type of reactions do carbonyls undergo

Nucleophilic addition

During the addition of HCN to carbonyls, where can H+ ions come from

HCN Water Dilute acid

When HCN is added to carbonyls, what is formed

Hydroxynitrile

What is the priority group in hydroxynitriles

Nitrile

How are hydroxynitriles named

Nitrile suffix Hydroxy prefix

What can aldehydes be reduced into

Primary alcohol

What can ketones be reduced into

Secondary alc

What is the most common reducing agent for carbonyls

NaBH4

What is a nucleophile

An atom or group of atoms that is attracted to an area of electron deficiency where it donates an electron pair

What is a negative hydrogen ion called

Hydride ion

What is the nucleophile from HCN

CN-

Where is the lone pair on CN-

Carbon

What is used to provide hydrogen cyanide (HCN)

Sodium cyanide Sulphuric acid

Hydrogen cyanide (HCN) properties

Colourless Poisonous Liquid Boils slightly above room temp

which carboxylic acids are soluble

up to 6 C

are carboxylic acids strong or weak acids and why

weak partially ionises equilibrium lies to the left

what do carboxylic acids dissociate into

carboxylate ion proton

dicarboxylic acids state at room temp

solid

do dicarboxylic acids dissolve readily in water

yes

test for carboxylic acids

add carbonate effervescence

carboxylic acid + alkali

salt + water

carboxylic acid + metal oxide

metal salt + water

carboxylic acid + carbonate

salt + water + carbon dioxide

what is a carboxylic acid derivative

compound that can be hydrolysed to form the parent carboxylic acid all have an acyl group

what is the ester functional group

COO

how do esters smell

sweet fruity

how are esters formed with a carboxylic acid and an alcohol

condensation reaction conc sulphuric acid catalyst heat under reflux reversible reaction low yield

how are esters formed with an acid anhydride and an alcohol

room temp no catalyst not reversible reaction higher yield

which is more reactive: acid anhydride or carboxylic acid

acid anhydride

what happens when esters are heated under reflux with dilute acid

reversible reaction carboxylic acid and alcohol produced

what happens when esters are heated under reflux with dilute alkali

irreversible reaction forms alcohol and carboxylate salt which needs further acidification to make carboxylic acid

acyl chloride functional group

COCl

how are acyl chlorides formed

carboxylic acid and liquid sulfur dichloride oxide (SOCl2) forms acyl chloride, HCl, SO2

what type of reactions can acyl chlorides undergo

addition elimination

what does hydrolysis of acyl chlorides form

carboxylic acid HCl

why is hydrolysis of acyl chlorides an addition- elimination reaction

H2O added across C=O HCl eliminated

what can acyl chlorides react with to form esters

alcohols or phenols

what is required to form an ester from an acyl chloride and a phenol

heat a base eg NaOH

what does the reaction of an acyl chloride and ammonia form

primary amide

what does the reaction of an acyl chloride and a primary amine form

secondary amide

metal carbonate state at room temp

solid

order from most to least reactive: acid anhydride carboxylic acid acyl chloride

acyl chloride acid anhydride carboxylic acid

What is the r group in an aliphatic amine

Alkyl group

What is the r group in an aromatic amine

Benzene or phenol

How many bonds does nitrogen make

How to name a primary amine with the amine group on carbon 1

Add suffix amine to alkyl chain

How to name a primary amine with the amine group not on carbon 1

Prefix amino w position number To alkyl chain

How to name secondary/tertiary amines with the same groups attached to the N

Prefix di/tri, alkyl Followed by amine

Now to name secondary/ tertiary amines with different groups attached to the N

Longest chain next to ‘amine’ then N (italics) in front of each alkyl group Alkyl groups in alphabetical order

Are amine/ammonium salts soluble in ionic compounds

Yes Shorter chain is more soluble

How do amines/ ammonia act as bases in aqueous solutions

Accepting a proton By donating its electron to pair a proton to form a dative bond

what does a halogenalkane and ammonia form

primary amine

what type of reaction is the reaction between a halogenalkane and ammonia

nucleophilic substitution

conditions for the reaction between a halogenalkane and ammonia

heat ethanol under pressure

what does the reduction of nitriles form

primary amine

conditions for reduction of nitriles

nitrile vapour and hydrogen gas passed over a nickel catalyst or LiAIH4

what does a halogenalkane and primary amine form

secondary amine

what type of reaction is the reaction between halogenalkanes and primary amine

nucleophilic substitution

conditions for reaction between halogenalkane and primary amine

ethanol heat in a sealed tube under pressure

what are the 2 steps to reduce nitrobenzene into phenylamine

reduction of nitrobenzene formation of phenyl amine

details ab reduction of nitrobenzene

tin and HCl act as reducing agents heat under reflux- boiling water bath phenylammonium ions protonated due to acidic conditions

What are the 2 functional groups in amino acids

Amine, carboxylic acid

What does amphoteric mean

Can act as both acids and bases

Are amino acids amphoteric

Yes

What type of amino acids are naturally occurring

2-aminocarboxylic

What do naturally occurring amino acids form

Building blocks that make up proteins

Now many naturally occurring amino acids are there

Now does the amine group of amino acids react

Basic so reacts with acids To form salts

What does the carbolic acid group of amino acids form when it reacts with aqueous alkali

Salt and water

What are the conditions for esterification of the carboxylic acid group of amino acids

Heat Concentrated sulfuric acid

Apart from forming an ester, what else happens during the esterification of the carboxylic acid group of amino acids

Amine group protonated Due to the acidic conditions

Do branched or unbranched compounds hare more points of contact

Unbranched

what are the 2 types of stereoisomers

geometrical (E/Z) optical

what is a chiral carbon/ centre

C w 4 diff atoms/ groups of atoms attached

how many optical isomers do chiral molecules exist as and what are the called

2 enantiomers

what type of reaction forms amides

condensation Nucleophilic addition- elimination

what is used to made amides

carboxylic acid/ acyl chloride + ammonia/ amine

amide general formula

RCONR2

what element is looked at to classify if amides are primary/ secondary/ tertiary

how to name primary amides

add -amide to stem

how to name secondary and tertiary amides

alkyl chain on N at the start prefixed w N- chain w carbonyl w -amide

What is needed to make a polyester using 1 monomer

Hydroxycarboxylic acid (has both OH and COOH functional group)

What is needed to make a polyester using 2 monomers

Dioc acid Diol

What is the by product when forming polyesters

Water

what type of bond is in polyesters

ester bond/ link

What functional groups needed to make polyamides

COOH/ COCl And NH2

What are the monomers in proteins

Amino acids

What bond is in proteins

Peptide

Are polyesters and polyamides biodegradable

Yes

Are polyalkenes biodegradable

What does acid hydrolysis of polyamides form

COOH and ammonium ions

What does alkaline hydrolysis of polyamides form

COO salt and amine

What does acid hydrolysis of polyesters form

OH and COOH

What does alkaline hydrolysis of polyesters form

OH and COO salt

can acyl chlorides be hydrolysed

yes

how are nitriles formed

KCN in ethanol heated under reflux w haloalkane nucleophilic substitution

what mechanism is used to add HCN to carbonyls

nucleophilic addition

what does hydrolysis of nitriles by dilute acid form

COOH ammonium salt

what does hydrolysis of nitriles by dilute alkali form

COO- ammonia

what are nitriles reduced to

amines

how are nitriles reduced

nitrile vapour and H2 passed over Ni catalyst or LiAIH4 in dry ether

how to purify an organic solid

recrystallisation: dissolve in minimum amt of hot solvent cool filter wash in cold solvent dry

what do impurities do to the melting point of a solid

lower it

what does aliphatic mean

not aromatic (no benzene)

do COOH give a positive 2,4-DNP test

what does it mean when a hydrocarbon burns with a sooty yellow flame

incomplete combustion producing C instead of CO

is phenol acidic

yes weak acid pH 5-6

what does homo lytic fission form

radicals

what type of fission is the normal one in mechanisms

heterolytic

does Na2CO3 react w OH and COOH

no only COOH

does NaOH react w OH and COOH

yes

what is formed when nitrobenzene is reduced

phenylamine water

Formula to find out how many optical isomers

2^n n is how many chiral centres

in gas chromatography, what is used to confirm the concentrations of components in a mixture

calibration curves

in gas chromatography, what gives proportions of components in a mixture

the relative peaks

in gas chromatography, what can the compounds in a mixture be identified from

their retention time

Is benzene unsaturated or saturated

Unsaturated

organic chem and analysis Flashcards

(151 cards)