Organic & Analysis

how does the carbon-halogen bond enthalpy influence the rate of reaction?

weaker bond enthalpy = faster rate of reaction

catalytic cracking products

aromatic hydrocarbons and motor fuels

carboxylic acid test

add Na2CO3, bubble through limewater

thermal cracking products

lots of alkenes

conditions for elimination

hot and dissolved in ethanol, concentrated

why do major products form the most?

a tertiary carbocation has more alkyl groups that stabilise the carbocation with a positive inductive effect, so they tend to form in larger quantities

conditions for fermentation

• presence of yeast

• anaerobic

• 25 - 42 degrees C

PVC uses

usually used for drain pipes. if plasticisers are added they keep the hydrocarbon chains further apart weakening the van der waals between chains making the molecule more flexible so they slide easily over each other

test for unsaturation

shake with bromine water, brown → colourless

why are addition polymers unreactive?

strong C-H and C-C bonds, is non-polar

acidified K2Cr2O7 + 1°/ 2°/ 3°

• 1° orange → green aldehyde R−CH=O group. excess dichromate + heat under reflux → carboxylic acid

• 2° orange → green ketone C=O group

• 3° no change

• aldehydes orange → green

Tollen’s test

1° + K2Cr2O7 → aldehyde

aldehyde + Tollen’s colourless → silver mirror

Fehling’s test

1° + K2CrO7 → aldehyde

aldehyde + Fehling’s blue → brick red

ethene → ethanol catalyst?

hot sulfuric acid

are alcohols soluble?

shorter chain alcohols are because the H bonding dominates, longer chain alcohols aren’t because the non-polar chain dominates

molecular ion definition

the molecule with a single positive charge

more vibrations → ?

more IR absorbed → warmer earth (more is remitted)

nucleophilic substitution conditions

warm, aqueous, (excess ammonia)

electrophilic addition conditions

warm, aqueous, ethanol

OH peak

narrower and rounder for alcohols, broader in carboxylic acids

N—H peak

quite a shallow peak, near OH peak. NH2 will fork due to 2 NH bonds having slightly different wavenumber

C=O peak

very sharp peak near 1730

structural isomerism

same molecular different structural formula

chain isomerism

same molecular formula different longest chain length due to branching

positional isomerism

different position of a functional group on each isomer

functional group isomerism

same molecular formula different functional group

stereoisomerism

same molecular formula different arrangement of atoms in space