organic chem detaily bits

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thermal cracking

high temps 1000 degrees, 70atm pressures

produces alkenes (e in thermal)

used to make polymers

catalytic cracking

zeolite catalsyt, slight pressure, 450 degrees

produces aromatic (a for aromatic) and motor fuels

cuts cost and works faster

sulfur dioxide

formed from combustion of sulfur containing hydrocarbons

removed by powdered calcium carbonate with water —> alkaline slurry

acidic gas reacts with calcium to form calcium sulfite

CaCO₃ + 2H₂O + SO₂ → CaSO₃ + 2H₂O + CO₂

NO_x

react w/ sunlight to form ground level ozone

removed by catalytic converters

C-X bond enthalpy

C-F strongest C-Cl moderate, C-Br weaker, C-I weakest

C-I substituted more readily

fluorine has less electrons so smaller in size and greater electronegativity making it hold bonds more tightly.

carbocations

more alkyl groups = more stable carbocation as they push electron density towards the positive charge

name what type of carbocation is used

used for asymmetrical alkenes electrophilic substition

PVC

polychloroethene

long closely pakced polymer chains, strong van der waals forces of attraction so brittle at room temperature - used in piping

plasticisers used to make more flexible by inserting between polymer chains, reducing strength of intermolecular forces

biofuel

fuel made from biological material which recently died

biofuel production

producing ethanol from glucose fermentation

carried out by yeast in anaerobic conditions

yeast - produces enzyme converting glucose into ethanol and CO2

30-40 degrees - optimum temperature for enzyme

anaerobic - prevents oxidation of ethanol to ethanal

separated using fractional distillation

carbon neutrality

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

2C₂H₅OH + O₂ → 4CO₂ + 6H₂O

net 6 moles when considering photosynthesis, fermentation and combustion

however fossil fuels burnt to operate machinery and transport biofuel so not completely carbon neutral

hydration to form ethanol

ethene

steam at 300 degrees

60 atm

solid phosphoric acid catalyst

elimination of alcohol benefits

produces alkenes from renewable sources eg biofuels so polymers can be produced without crude oil

risks of KCN

irritant and dangerous if inhaled

reacts with moisture to produce highly toxic HCN

gloves, safety goggles, lab coat, fume cupboardndustri

advantages of ethanoic anhydride

cheaper

safer as less corrosive, reacts less virgously and does not produce dangerous HCl fumes

produces -COOH instead of HCl

uses of aromatic amines

dyes

benzene

planar cyclic structure

all c-c bonds are the same os have the same bond length 140pm, between single 154pm and c=c 135pm

each carbon has delocalised p orbital forming a ring making them more stable

benezene stability

delocalised p orbital leads to increased stability

cyclohexene enthalpy change -120kJmol

expected for benzene 3 double bonds = -360

however experimental is -208

breaking bonds is endo, so more energy put into breaking benzene so is more stable

enzyme specificity

enzymes proteins made up of amino acids, so contain chiral centres

active sites are stereospecific - only work on one enantiomer of a substrate and not the other enantiomer, will not fit so will not be catalysed

drugs as inhibitors

block active site of enzyme and stop it from working

very specific so hard to find complementary drug - especially if chiral as only one enantiomer will fit into active site

computers used to model shape of active site and predict potential drug molecules that would interact

H NMR conditions

standard TMS as has 12 hydrogen in identical enviroments, producing single absorption peak far from other peaks at 0

• non toxic, inert, low boiling point

samples should be dissolved in inert solvent with no protons as they would produce peaks

(1 peak for carbon NMR)

CCl₄ non-polar so good for non polar organic substances

CDCl₄ polar so good for dissolving polar substances

column chromatography

purifying organic product and separate sols

• pack glass column with solid slurry of absorbant material (stationary phase)

• mixture added to top and allowed to drain

• solvent added through column (mobile phase)

• components separate by solubility in mobile phase and how strongly they are adsorbed onto stationary phase

• more soluble in mobile phase = quicker through column

gas chromatography

separating volatile liquids for identification

• stationary phase solid coated in viscous liquid packed into long tube, coiled to save space and built into oven

• mobile phase unreactive carrier gas eg nitrogen

• each component takes different time from being injected to detected on other side - retention time

• run known sample for comparison and identification

• area under peaks tell you relative amount

• higher affinity for mobile phase = faster retention time

GC-MS

sample separated using gas chromatography then fed into mass spec

spectrometer produces mass spectrum for each component used to idenity each one and show what original sample consisted of

TLC

separating mixtures simply

• stat phase thin silica layer fixed to plate

• pencil line near bottom of plate and put small drop of sample

• allow to dry and place plate in beaker with small volume of solvent (mobile phase)

• more soluble = travels further

• remove plate before solvent reaches top and mark solvent front with pencil

• place in fume cupboard to dry as fumes may be toxic