Organic

halogenoalkanes with hydroxide ions (nuc sub)

• warm aqueous NaOH (water can be used but much slower)

• under reflux

• nucleophilic substitiution

• product: alcohol

halogenoalkane with cyanide ions

• warm ethanolic KCN

• under reflux

• nucleophilic substitution

• product: nitrile

halogenoalkane with ammonia

• heat with ethanolic ammonia

• must be excess ammonia

• nucleophilic substitution

• product: amine (identified by fishy smell)

halogenoalkanes with hydroxide ions (elim)

• warm ethanolic NaOH

• under reflux

• elimination reaction

• product: alkene

when a halogenoalkane reacts with NaOH, we can make…

• alkene when solvent is ethanol (OH act as base)

• alcohol when solvent is water (OH act as nucleophile)

general formula for alcohols

CnH2n+1OH

formation of chloroalkanes

• alcohol + PCl5 or HCl

• ROH + PCl5 —> RCl + HCl + POCl3

• ROH + HCl —> RCl + H2O

2-chloro-2methylpropane can by purified by…

distillation

in which order do alcohols react with HCl

primary - slowest

tertiary - fastest

formation of bromoalkanes

• alcohol + halide ion (NaBr)

• acid catalyst (50% H2SO4)

• H2SO4 reacts with NaBr intialy to form HBr. HBr reacts with alcohol to form bromoalkane

formation of iodoalkanes

• alcohol + PI3

• 3ROH + PI3 —> 3RI + H3PO3

• PI3 made in situ unnder reflux with alcohol

dehydration of alcohols

• forms alkenes

• acid catalyst (H2SO4 or H3PO4)

test for aldehyde

fehlings —> blue to brick red

method for separation + purification

separation

• add products into separating funnel

• add water to dissolve soluble inpurities and create aq solution

• allow solution to settle, 2 layer form: top layer - impure product, bottom layer - aq layer contianing impurities

• drain aq layer off

purification

• transfer impure product to round bottom flask

• add anhydrous CaCl2 - removes aq substances remaining

• invert flask, leave for 30 mins

• filter solid drying agent

sn1 or sn2

primary - sn2

tertiary - sn1

test for aldehydes (potassium di…)

• K2Cr2O7 oxidises aldehydes but not ketones

  • colour change from orange to green

test for aldehydes (toll…)

• tollens reagent

• add tollens to sample and place in hot wate bath (do not use flame as -CHO and ROR are flammable

• tollens reduce to silver, coating inside of glass in presence of aldehydes

• made by reacting silver nitrate with aqueous ammonia

reduction of aldehydes and ketones

• resucing agents such as NaBH4 dissolved in methanol and water can reduce aldehydes and ketone

• ketones resuced to 2’ alcohol

• aldehyde reduced to 1’ alcohol

kcn + carbonyl compounds

• kcn reacts with carbonyl compounds to forn hydroxynitriles

• nuc add

• kcn dissolved in acid OR hcn, no acid needed

assesing risk of kcn

• irritant, very dangerious if ingested or inhaled

• when react with moisture, can form toxic gas hcn

reducing risks of kcn

• wear lab coat to prevent cloting contamination

• safety goggles

• fume cupboard to prevent exposure to toxic fumes

• wear gloves whilst handling

test for carbonyl group

• 2,4 DNPH

• dissolved in sulfuric acid and methanol

• positive test: orange ppt

• only reacts with C=O in aldehydes and ketones

analysis of 2,4 DNPH ppt

• ppt is a derivative of carbonyl compound

• purify through recrystallysation

• different carbonyls, different derivative so unique melting point

• identifies against library of known melting points

test for methyl carbonyl

• either ethanal of methyl ketone

• iodine heated in presence of alkaline

• iodoform

• yellow precipitate, CHI3 (triiodomethane)

effect of dimers

net effect is boiling point increases as the ‘joined molecules’ are larger and so intermolecular forces are greater

making carboxlic acids

• hydrolysis of nitriles

• oxidation of aldehydes

• oxidation of primary alcohols

carboxylic acid + carbonate

• form carbon dioxide, salt, water

reduction of carboxylic acids

• LiAlH4 in dry ethoxyethanoate

formation of acyl chloride

carboxylic acid + PCl5 —> acyl chloride + POCl3 + HCl

formation of ester

• carboxylic acid + alcohol

• sulfuric acid catalyst

• under reflux

• ester sepreated in disillation - mus be done in stu as reaction is reversible

• Na2CO3 added to purify further and remove and carboxylic acid remaining

• layer after addition of Na2CO3 is ester, separated using sperating funnel

properties of esters

• used in perfumes and food flavorings

• sweet smells - pear drops

• polar solvent - used in glues

• low boiling point

• used to make plastic more flexile during polymerisation process

  • however can leach our

ester hydrolysis (acid hydrolysis)

• dilute sulfuric or hydrochloric acid

• under reflux

• split into carboxylic acid and alcohol

ester hydrolysis (base hydrolysis)

• dilute NaOH

• under reflux

• splits into carboxylate ion and alcohol

polyester formation

• dicarboxylic acid + diol

• ester link formed

• condensation polymersation

acyl chloride + water

• produces carboxylic acids + HCl

• vigorous reaction, misty white fumes (HCl)

acyl chloride + ammonia

• produces amides + HCl

• vigorous reaction, misty white fumes (HCl)

acyl cloride + alcohol

• forms an ester + HCl

• vigorous reaction, misty white fumes (HCl)

acyl chloride + amines

• produces n substituted amides + HCl

• vigorou reation, misty white fumes (HCl)