Organic Flashcards
(19 cards)
molecules can absorb IR radiation
covalent bonds vibrate and leads to change in dipoles
homolytic fission
breaking of a covalent bond with each atom getting one electron from the covalent bond to form two radicals
heterolytic fission
one atom gets the bonding pair of electrons from the covalent bond
free radical
a species with an unpaired electron (represented as •) which is highly reactive
acid hydrolysis of esters
H2O, H+ catalyst, reflux
ester + water alcohol + carboxylic acid
alkali hydrolysis of esters
H2O, OH- catalyst, reflux
ester + NaOH -> alcohol + sodium carboxylate
making soap
alkaline hydrolysis (3NaOH) of triglycerides to produce long chain carboxylic acid salt 3RCOONa and glycerol o Long-chain carboxylic (fatty) salt is used for soap as the hydrophylic COO- attaches with water and the non-polar hydrocarbon chain attaches with grease
making biodiesel
react triglyceride (from veg oil) with 3 methanol using strong alkali catalyst to form a mixture of methylesters and glycerol
ethanedioic acid is a stronger acid that ethanoic acid
carboxylic acid is R-COOH
ethandioic acid has R group COOH
ethanoic acid has R group CH3
unionised COOH contains two very electronegative O
has a negative inductive effect
CH3 group has a postive inductive effect
OH bond in ethanedioic acid is more polarised so H becomes more δ+
more dissociation into H+ ions
what do amines act as
bronsted lowry base as the lone pair of electrons on N are readily available to accept a proton so are weak bases
strongest to weakest base: primary aliphatic amine, ammonia, phenylamine
primary aliphatic amine > ammonia > phenylamine
Primary aliphatic: stronger base than ammonia as the lone pair is more readily available due to positive inductive effect of electron releasing alkyl group
CH3NH2 + H2O ⇌ CH3NH3+ + OH-
Ammonia: availability of lone pair is used as a standard as there are no other groups attached
NH3 + H2O ⇌ NH4+ + OH-
Phenylamine: weaker than ammonia as lone pair is less available due to negative inductive effect of electron withdrawing benzene ring
(benzene)NH2 + H2O ⇌ (benzene)NH3+ + OH-
difference between benzene and cyclohexa-1,3,5-triene
- All bonds lengths are equal in benzene
- Bromine only produces one form of 1,2-disubstituted bromine when substituted with Br2
- Does not decolourise bromine water
- ΔHyd(benzene) is lower than ΔHyd(cyclohexa-1,3,5-triene) as benzene is more thermodynamically more stable
why is benzene more thermodynamically stable than cyclohexa-1,3,5-triene
Each carbon atom donates an electron from the p orbital to form a delocalised electron cloud above and below the benzene ring so delocalisation is spread out
ΔHyd(benzene) = -208kJmol-1
ΔHyd(cyclohexa-1,3,5-triene) = -360kjmol-1
delocalisation (resonance) energy = 152kJmol-1 more stable and less exothermic than expected
which is more stable: cyclohexa-1,3-diene or cyclohexa-1,4-diene
ΔHyd(cyclohexa-1,3,-diene) more stable than ΔHyd(cyclohexa-1,4,-diene)
ΔHyd(cyclohexa-1,3,-diene) = -232kJmol-1 as the C=C bonds are close together so the p orbitals merge and delocalisation overlaps giving extra stability
ΔHyd(cyclohexa-1,4,-diene) = -240kJmol-1 as the C=C bonds are far apart and is double ΔHyd(cyclohexene)
environmental advantage of condensation polymers over addition polymers
biodegradable - readily undergo hydrolysis due to polar bonds δ+C=O δ- attract attacking species e.g. nucleophiles, NaOH, HCl aq
break amide linkage
hydrolysis breaks amide linkage between CO and NH of two amino acids using HCl 6moldm-3 catalyst
how does cisplatin work
2 Cl- ions are displaced, Pt form dative covalent bonds with N in 2 different guanine bases (substitutes for Cl- ligands)
Prevents DNA replication of cancer cells as it disrupts the structure
standard for NMR spec
Standard is tetramethylsilane (TMS)
• TMS is inert so will not react with sample
• 12 equivalent proton so only gives one signal
• Non-toxic, has a low boiling point so can easily be removed from sample afterwards
solvent for NMR spec
E.g. CCl4, CDCl3
o Solvent must not contain 1H atoms as they will appear in the spectrum and interfere
o Solvent contains deuterium (D or 2H ) which is an isotope of hydrogen
o Low boiling point so can easily remove from sample and unreactive
