year 2 organic chem Flashcards
describe benzene
-each C has 3 covalent bonds
-spare electrons overlap
-to form a cloud of delocalised electrons
-planar
-6C compound in a ring structure
-C-C bonds equal in length
-expected enthalpy of hydrogenation is -360
-actual enthalpy is less exothermic by 152
-benzene is more stable
conditions for the nitration of benzene
-conc. HNO3
-conc. H2SO4 catalyst
equations for the formation of the electrophile for the nitration of benzene
HNO3 + H2SO4 –> H2NO3^+ + HSO4^-
H2NO3^+ –> NO2^+ + H2O
reagents, conditions and product for the acylation of benzene
-acyl chloride
-halogen carrier catalyst - AlCl3
-anhydrous
-produces phenylketone
2 ways to make aliphatic amines
nucleophilic substitution of a haloalkane with ammonia
reducing a nitrile
why is nucleophilic substitution of a haloalkane with ammonia inefficient
-the amine produced is a base so can act as a nucleophile leading to further substitutions with the haloalkane
-until a quaternary ammonium salt is produced which can’t undergo further substitutions
-large XS of ammonia used at start of reaction to give greater yield of primary amine
what is the use of quaternary ammonium salts
-cationic surfactant
-used in fabric and hair conditioners
reagents and conditions to produce an amine by reducing a nitrile
H2 gas
nickel catalyst
compare the base strength of amines
-the more available the lone pair, the stronger the base
-alkyl groups are electron pushing so the electron density on the N atom is increased
-methylamine is a strong base
-benzene is electron withdrawing
-lone pair on N is less available
-phenylamine is weak base
how are aromatic amines synthesised
reducing nitrobenzene
what are the reagents, conditions and products for reducing nitrobenzene
tin and conc HCl
forms an ionic salt
NaOH is used to neutralise the salt to phenylamine
what is phenylamine used for
starting molcule for dyes and pharmaceuticals
how are polyesters made
diacyl chloride + dialcohol –> polyester + HCl
-faster but produces hazardous HCl
dicarboxylic acid + dialcohol <–> polyester + water
-slower, reversible
example of a polyester
Terylene
benzene-1,4-dioic acid + ethan-1,2-diol
how are polyamides made
diacyl chloride + diamine –> polyamide + HCl
-faster but produces hazardous HCl
dicarboxylic acid + diamine <–> polyamide + water
-slower, reversible
examples of polyamides
Kevlar
1,4- diaminobenzene + benzene-1,4,-dioic acid
Nylon
1,6-diaminohexane + hexane-1,6-dioic acid
compare the the IMF of addition polymers and condensation polymers
-condensation stronger and more rigid
-C-N and C-O bonds in condensation polymers are polar so they have d-p d-p and H bonds between polymers
compare the reactivity of addition polymers and condensation polymers
-condensation polymers are more reactive have polar bonds in their chains which can be attacked by nucleophiles
-condensation polymers are therefore biodegradable whereas addition polymers aren’t (strong non-polar covalent bonds)
what are optical isomers
-arises when a compound contains a carbon atom with 4 different groups attached to it
-the enantiomers are non-superimposable
-they rotate plane-polarised light in opposite directions
what is a racemic mixture
-contains equal quantities of each enantiomer
-has no effect on plane polarised light
-forms due to planar C=O bond so equal chance of nucleophile attacking from above or below bond
what are the reactants, conditions and products for the reduction of aldehydes and ketones
-nucleophilic addition
-NaBH4 reducing agent
-produces alcohols
what are the reactants, conditions and products for the nucleophilic addition of aldehydes and ketones
-acidified KCN (not HCN as it is a toxic gas)
-produces hydroxynitriles
what are the characteristic reactions of carboxylic acids
-same as normal acids
+ metal –> salt + hydrogen
+ carbonate –> salt + water + CO2
+ alkali –> salt + water
how are esters formed
carboxylic + alcohol –> ester + water
H2SO4 catalyst
uses of esters
-food flavouring/ perfumes
-solvent
-plasticiser to make plastics more flexible
-used to make soap and biodiesel
what is the difference between acid and base hydrolysis of esters
acid hydrolysis produces alcohol and carboxylic acid
base hydrolysis produces alcohol and carboxylate ion
how to make soap
-triester is made from 3 carboxylic acids and glycerol
-soap is formed by hydrolysing triesters with conc. NaOH
-forms glycerol and sodium salt (soap)
how to make biodiesel
-react triester with methanol with KOH catalyst
-produces glycerol and a mixture of methyl esters (biodiesel)
reactions of acyl chlorides with water, alcohol, conc NH3 and amines
+ water –> carboxylic acid + HCl gas
+ alcohol –> ester + HCl gas
+ conc. NH3 –> amide + HCl gas
+ amine —> N-substituted amide + HCl gas
for acid anhydrides, carboxylic acids replace the HCl gas
compare acyl chloride and acid anhydride reactions
-acyl chlorides have more vigorous reactions
-acyl chlorides produce HCl gas which is very corrosive. acid anhydrides produce carboxylic acids which are less corrosive
-acyl chlorides generally more expensive
structure of amino acids at a high and low pH
low pH - NH2 –> NH3^+
high pH - COOH –> COO^-
zwitterions have both
what is the primary, secondary and tertiary
primary- held by covalent bonds between amino acids via condensation reactions
secondary- either a helix or b pleated sheet formed due to H bonds between groups in polypeptide
tertiary- held by H bonds, ionic bonds, disulfide bridges and VDW
which C of the 2-deoxyribose does the base and phosphate attach to
phosphate - carbon 5
base- carbon 1
how many H bonds does each base pair form
C and G form 3
A and T form 2
how does cisplatin work as an anti cancer drug
N atom on guanine base in DNA forms coordinate bond with Pt, replacing a chloride ligand
another N on guanine in opposite strand replaces the 2nd chlorine
DNA disrupted- cant unwind and replicate
cells stop dividing
evaluate cisplatin
also targets healthy cells that divide frequently e.g. hair
to combat this, low dosages are given, targeted to tumour
benefits outweigh side effects
what standard substance is used in NMR spectroscopy and why
tetramethylsilane (TMS)
silicon with 4 methyl groups attached
chemically unreactive
12 H atoms in identical environments
produces a single peak away from other peaks
volatile and easily removed from sample after
describe the mobile and stationary phase in chromatography
stationary phase- molecules can’t move (either solid or liquid on solid support)
mobile phase - molecules can move (always liquid or gas)
the mobile phase moves over the stationary phase
more soluble/attracted to mobile phase - travels further
more retention/attracted to stationary phase moves less
how is a crystalline solid separated and purified
-filter
-dissolve in min amount of hot solvent
-cool and filter under reduced pressure
-wash with cold water and dry
