Topic 4 - Core Organic Chemistry Flashcards

Question

What is the carboxyl group and where is it found?

Answer 1

COOH is the carboxyl group, found in carboxylic acids

Answer 2

the pattern of reactivity

Answer 3

physical properties such as melting/boiling points

Answer 4

Carbon atoms arranged in chains (branched and unbranched)

Answer 5

Carbon atoms arranged in ring structures

Answer 6

carbon atoms using benzene structure

Answer 7

The alkyl group (the alkane subtract a H)

Answer 8

- Cl - Br - I

Answer 9

This is the number of carbon atoms in the longest chain bearing the functional group

Answer 10

This shows the position and identity of any side chain substituents

Answer 11

This shows the functional group is present

Answer 12

Take 'ane' off the alkane name

Answer 13

-oyl chloride

Answer 14

1. number the longest carbon chain from one end to give the lowest numbers to the side chains 2. Sidechain names appear in alphabetical order 3. Each side chain is given its own number 4. If identical side-chains appear more than once, prefix with di, tri, tetra, penta, hexa etc 5. Numbers are seperated from names by hyphen (2-methylheptane) 6. Numbers are seperated from numbers by a comma (2,3-dimethylbutane)

Answer 15

tells us the actual number and type of atom in a compound

Answer 16

this is the simplest whole number ratio of atoms in compound

Answer 17

General formula CnH2n+2 CH3 CH2 CH2 CH3 is the structural formula Molecular formula is C4H10 Empirical formula is C2H5

Answer 18

These show carbon chains and major functional groups only, H’s are not shown

Answer 19

At the end of lines

Answer 20

Structural isomers are compounds with the same molecular formula but different structural formulae.

Answer 21

C3H10 can be shown in two ways: .CH3CH2CH2CH3 .CH3CH(CH3)CH3

Answer 22

In compounds containing a functional group, the functional group can be at different positions along the carbon chain.

Answer 23

Sometimes two molecules containing different functional groups have the same molecular formula. Aldehydes and Ketones with the same number of carbon atoms have the same molecular formulae. The molecular formula C3H6O could represent propanal or propanone.

Answer 24

Linalool and geraniol are isomers and have similar chemical properties that are used in perfumes. Linalool smells of lavender and geraniol of roses.

Answer 25

homolytic fission or heterolytic fission.

Answer 26

When covalent bonds break by homolytic fission, each of the bonded atoms take one of the shared pairs of electrons from the bond. .Each atoms now has a single unpaired electron

Answer 27

.An atom or groups of atoms with an unpaired electron

Answer 28

When a covalent bond breaks by heterolytic fission, one of the bonded atoms takes both of the electrons from the bond .The atom that takes both electrons becomes a negative ion .The atom that does not take the electron becomes a positive ion

Answer 29

information about how the reaction takes place

Answer 30

the movement of electron pairs when bonds are being broken or made.

Answer 31

show the movement of a single unpaired electron in mechanisms involving mechanisms.

Answer 32

Addition, subsituton and elminiation

Answer 33

In an addition reaction, two reactants join together to form one product.

Answer 34

In a substitution reaction, an atom or group of atoms is replaced by a different atom or groups of atoms.

Answer 35

An elimination reaction involves the removal of a small molecule from a larger one. In an elimination reaction, one reactant molecule forms two products. Usually through a catalyst.

Answer 36

Molecules with the same molecular formula but a different structural formula

Answer 37

These are molecules with the same molecular formula, the same structural formula but a different spatial arrangement of atoms

Answer 38

. A c=c double bond (non rotating) | . Each c must have 2 different groups attached

Answer 39

Trans, across the isomer, the E isomer, think trans-Atlantic

Answer 40

Cis, adjacent isomer, the Z isomer, think stays the same

Answer 41

.A more up to date system gives priority to groups based on their atomic number (high number = high priority) when thinking where elements go on isomers

Answer 42

it is positive and so goes to the cathode

Answer 43

it is negative and so goes to the anode

Answer 44

A positive species which is able to accept a pair of electrons (means electron loving)

Answer 45

A negative species which is able to donate a pair of electrons (means nucleus loving)

Answer 46

single bonds between carbons only

Answer 47

The are among the most stable organic compounds – lack of reactivity

Answer 48

oil and gas

Answer 49

fuels to release energy

Answer 50

The overlap of orbitals directly between the bonding atoms leads to the formation of sigma bonds (σ-bonds).

Answer 51

Free rotation

Answer 52

As the carbon chain increases the boiling point increases

Answer 53

As the carbon chain length increases the surface are of interaction between molecules increases and thus the size of the London forces also increases (due to the greater number of electrons and thus size of temporary and induced dipoles), hence more energy needs to be provided to disrupt these stronger London forces, leading to a higher boiling point.

Answer 54

As the amount of branching increases, the boiling point goes down

Answer 55

As the amount of branching increases the surface area of interaction between molecules decreases and thus size of the London forces also decreases, hence less energy needs to be provided to disrupt these weaker London forces, leading to a lower boiling point.

Answer 56

.C-C and C-H bonds are strong (have high bond enthalpy) .C-C bonds are non-polar .C-H are virtually non-polar

Answer 57

In a plentiful supply of oxygen, combustion of alkanes will always lead to the production of CO2 and water.

Answer 58

In a limited supply of oxygen, combustion of alkanes will lead to the production of CO (carbon monoxide) and water.

Answer 59

The initiation step, the propagation step and the termination step

Answer 60

addition of two three radicals

Answer 61

X2  UV light  X● + X● CaHb + X●  CaHb-1 + HX CaHb-1● + X2  CaHb-1X + X● CaHb-1● + X●  CaHb-1X

Answer 62

.Further substitution can occur with more H’s being replaced by additional bromines .Additionally substitution can occur at different points in a carbon chain

Answer 63

Unsaturated

Answer 64

bromine water is decolourised (orange to colourless)

Answer 65

these are formed by the sideways overlap of the two adjacent p orbitals

Answer 66

The smell and flavour of lemons and oranges

Answer 67

The double bond opens up and allows two atoms to join to it

Answer 68

Addition reaction with hydrogen

Answer 69

nickel catalyst and 150'C

Answer 70

It cant pack as closely together

Answer 71

.Alkenes will react with steam, H2O, in the presence of phosphoric acid, H3PO4, to produce alcohols

Answer 72

Unsaturation

Answer 73

Br is more electronegative

Answer 74

HBr is polar due to electronegative Br The pi electrons attracted towards the Hs+, i.e. pi bond breaks Hs+ acts as an electrophile (accepts a pair of electrons) H-Br bond breaks via heterolytic fission

Answer 75

‘electron loving’, able to accept a pair of electrons

Answer 76

‘nucleus loving’, able to donate a pair of electrons

Answer 77

Both Br atoms have the same electronegativity

Answer 78

Bromine is none polar due to each atom having the same electronegativity But as bromine approaches the pi bond on the alkene, it repels the electrons in the bond and pushes them away, giving the bromine atoms slight charges The pi electrons induce a dipole in the non-polar Br2 molecule as it approaches the bond This means electrophilic addition can ensue

Answer 79

A carbocation (or carbonium ion) as it has a positive charge

Answer 80

Primary, secondary and tertiary

Answer 81

Carbon centres have a positive inductive effect (+I). This pushes electron density towards the C+ and helps to stabilise it.

Answer 82

the more stable the carbonium ion

Answer 83

more favourable

Answer 84

Major product

Answer 85

The major product is produced when the negative part of the molecule joins to the carbon with the least number of attached H (hydrogen) atoms within the double bond.

Answer 86

Primary carbonium ions are less stable than secondary, which are less stable than tertiary, because: - Primary = 1 x +I - Secondary = 2 x +I - Tertiary = 3 x +I

Answer 87

Check notes from 29.1.20

Answer 88

Around the monomer in the polymer, over the bonds on the edge

Answer 89

when lots of small alkene monomers join together to form a long chain molecule called a polymer (and no other product).

Answer 90

carier bags

Answer 91

used in cups, packaging and cutlery

Answer 92

Non-stick coatings

Answer 93

polyphenylethene

Answer 94

straight polymer chains, chains packed tightly together, strong forces between chains, strong and tough material, high melting point

Answer 95

branched polymer chains, chains cant pack close together, weak forces between chains, weak but flexible material, low melting point

Answer 96

the temperature and catalyst used during production

Answer 97

- Readily available - Cheap to use - More convenient than alternatives (glass, metal, paper and cardboard) - Lack of reactivity makes them suitable for storing food

Answer 98

- Non-biodegradable | - Growing amount of waste has environmental effects, for example killing marine life

Answer 99

by conserving finite fossil fuels as well as decreasing the amount of waste going into landfill.

Answer 100

First the polymers have to be sorted, as if they are mixed then the product is rendered useless, and then they are chopped into flakes, washed, dried and melted. The recycled polymer is cut into pellets and used by manufacturers to make new products.

Answer 101

The disposal and recycling of PVC is hazardous due to the high chlorine content and the range of additives present in the polymer. Dumping PVC in landfill is not sustainable and, when burnt, releases hydrogen and chlorine (a poisonous gas), and other pollutant like toxic dioxins.

Answer 102

Solvents dissolve the polymer, high-grade PVC is then recovered by precipitation from the solvent, and the solvent is used again.

Answer 103

as they are from petroleum or natural gas, they have a high stored energy value

Answer 104

Waste polymers can be incinerated to produce heat, which generates steam to turn a turbine to produce electricity

Answer 105

.Feedstock recycling describes the chemical and thermal processes that can reclaim monomers, gases, or oil from waste polymers

Answer 106

those produced from crude oil in refineries

Answer 107

raw materials for the production of new polymers

Answer 108

that it can handle unsorted and unwashed polymers

Answer 109

Bioplastics produced from plant starch, cellulose, plant oils, and proteins

Answer 110

not only protects our environment but also conserves natural resources

Answer 111

.Biodegradable polymers are broken down by microorganisms into water, carbon dioxide and, biological compounds

Answer 112

These polymers are usually made of starch or cellulose, or contain additives that alter the structure of traditional polymers so that microorganisms can break them down

Answer 113

No visible or toxic residues

Answer 114

can be used as bin liners for food waste, so the food and bin liner can be composted together

Answer 115

Compostable plates, cups and food trays made from sugar cane fibre

Answer 116

Where plant based polymers aren’t available, photodegradable oil-based ones are being developed

Answer 117

These polymers contain bonds that are weakened by absorbing light to start the degradation. Alternatively, light absorbing additives are used

Answer 118

methanol, ethanol, propanol, butanol, pentanol, hexanol

Answer 119

Butan-1-ol Butan-2-ol 2-methylpropan-1-ol 2-methylpropan-2-ol

Answer 120

1. Extract sugar (glucose) from crops 2. Add yeast to glucose (enzymes in yeast act as a catalyst) 3. Fermentation occurs

Answer 121

Batch process

Answer 122

C6H12O6 --> 2CH3CH2OH + 2CO2

Answer 123

.Sugars are a renewable resource .Batch process, so the equipment is cheap .More carbon neutral (bio fuel)

Answer 124

.Very slow .Very impure - needs further processing, fractional distillation, which takes time and money .Batch process, so high labour costs

Answer 125

.Extract crude oil from the ground .Oil refinery - fractional distillation then cracking to get ethene .Hydration (addition of steam)

Answer 126

.Phosphoric acid catalyst | .High temperature and pressure

Answer 127

C2H4 + H2O --> CH3CH2OH

Answer 128

.Fast reaction .Pure product .95% yield (initially 5% but can recycle unreacted ethene) .Continuous (cheaper man power)

Answer 129

.High technology equipment needed, expensive initial cost .High energy costs for high pressure .Ethene is non-renewable

Answer 130

alcohols are less volatile, have higher melting points and greater water solubility than the corresponding alkanes.

Answer 131

.Hydrogen bonding in alcohols gives higher boiling point

Answer 132

the significance of hydrogen bonding decreases, and London forces increase, therefore gap between boiling points starts to narrow

Answer 133

.Alcohols such as methanol and ethanol are soluble in water as hydrogen bonds form between the –OH group of the alcohol and the water molecules .As the chain length increases, the influence of the –OH group decreases, and the solubility of the alcohol decreases .Carbon chains are hydrophobic

Answer 134

primary, secondary and tertiary

Answer 135

depends on the number of hydrogen atoms and alkyl groups attached to the carbon atom that contains the alcohol function group

Answer 136

.Primary has at least 2 hydrogens attached to the carbon with the alcohol group, plus either a carbon centre or another H

Answer 137

.Secondary has 1 hydrogens attached to the carbon with the alcohol group, plus 2 more carbon centres

Answer 138

.Tertiary has 0 hydrogens attached to the carbon with the alcohol group, plus 3 more carbon centres

Answer 139

helps something to gain oxygen/lose electrons

Answer 140

Na2Cr2O7 | K2Cr2O7

Answer 141

2Cr^3+ + 7H2O

Answer 142

They are reduced

Answer 143

Carboxylic acid

Answer 144

Carboxylic acid

Answer 145

mild oxidation

Answer 146

further oxidation

Answer 147

Reflux then distillation

Answer 148

continuous evaporation then condensation, where the reactants cannot escape the flask

Answer 149

Carboxylic acid

Answer 150

CH3COOH + H2O

Answer 151

An oxidizing agent

Answer 152

A carboxylic acid group but just H instead of OH

Answer 153

Secondary alcohol + oxidising agent  ketone + water

Answer 154

Due to lack of hydrogen on OH carbon

Answer 155

Concentrated sulphuric acid (h2so4) or concentrated phosphoric acid (h3po4) are dehydrating agents i.e. they can remove water from molecules

Answer 156

Cyclohexene

Answer 157

A hydrogen from the carbon with the OH group and a neigbouring arbon are removed

Answer 158

C-F, then C-Cl, then C-Br, then C-I

Answer 159

Check your notes

Answer 160

C-X | X = F, Cl, Br, I

Answer 161

Halogens are very electronegative, so dipoles are formed, which makes them reactive

Answer 162

donates a pair of electrons

Answer 163

Haloalkane + hydroxide  alcohol + halogen

Answer 164

- Shielding - Nuclear charge - Atomic radius

Answer 165

the strength of the bond between the halogen and the carbon becomes weaker as you go down the group.

Answer 166

Haloalkane + ethanol + silver nitrate, time for precipitate

Answer 167

Check notes

Answer 168

repairing, 3O2 --> 2O3

Answer 169

NO- + O3 --> O2 + NO2- | NO2- + O3 --> NO- + 2O2

Answer 170

Check notes

Answer 171

O3 + Cl- --> OCl- + O2 | OCl- + O3 --> Cl- + 2O2

Answer 172

2O3 --> 3O2

Answer 173

Ozone is a layer in the stratosphere which stops UV rays

Answer 174

chlorofluorocarbons

Answer 175

Weakest bond broken by UV rays from sun (C-Cl)

Answer 176

We now instead use HFC’s (hydrofluorocarbons), which doesn’t make any free radicals, so the hole is now closing

Answer 177

Turn it into` oxygen

Answer 178

Cn¬H2n+1X | Where X is a halogen

Answer 179

Halogenoalkanes are similar to alkanes but with one or more of the hydrogen atoms replaced by a halogen

Answer 180

Fluorine Fluoro – Chlorine Chloro – Bromine Bromo – Iodine Iodo –

Answer 181

``` One - Two Di – Three Tri – Four Tetra – Five Penta – ```

Answer 182

A chain of carbon atoms can be represented by R when drawing the structure, this is referred to as an R group

Answer 183

- Primary (1’) halogenoalkanes | Have one R group attached to the carbon linked to the halogen

Answer 184

- Secondary (2’) halogenoalkanes | Have two R groups attached to the carbon linked to the halogen

Answer 185

- Tertiary (3’) halogenoalkanes | Have three R groups attached to the carbon linked to the halogen

Answer 186

... the different electronegativity of the carbon and halogen atoms

Answer 187

... halogen atom than towards the carbon atom

Answer 188

It decreases

Answer 189

- Nucleophiles (Nu-) attack the carbon of a carbon–halogen (C–X) bond, because the electron pair on the nucleophile is attracted towards the small positive charge on the carbon - The electrons in the C–X bond are repelled as the Nu- approaches the carbon atom - The Nu- bonds to the carbon and the C–X bond breaks. The two electrons move to the halogen, forming a halide ion - The halide is substituted, so this is a nucleophilic substitution reaction

Answer 190

H2O, -OH, NH3

Answer 191

... alcohol

Answer 192

... a reaction with water or aqueous hydroxide ions that breaks a chemical compound into two compounds

Answer 193

.Alkaline hydrolysis with NaOH(aq)/H2O, reflux: R-X + OH-  R-OH + X- .Acidification with dilute nitric acid, this removes excess NaOH which would otherwise form a precipitate with the silver nitrate in the next stage, preventing detection of any silver halides .Addition of AdNO3(aq) ¬shows the presence of aqueous halide ions Ag+(aq) + X-(aq)  AgX(S)

Answer 194

... the extent and rate of the hydrolysis

Answer 195

1. Set up water bath to a temperature of 50'C at the start of the lesson 2. Set up five test tubes and allow them to reach 50 'C 3. Place a separate test tube containing silver nitrate into the water bath and allow this to reach the same temperature 4. One tube at a time, add 1cm3 of the silver nitrate solution, mix the contents and start the timer 5. Note the time it takes for a precipitate to form 6. Repeat this with the other tubes and note the results

Answer 196

5. Halogenoalkanes are insoluble in water, but soluble in ethanol

Answer 197

.A high concentration of O3 molecules about 15-30Km above the Earth’s surface .Ozone absorbs a high proportion of the Sun’s ultraviolet radiation

Answer 198

... ultraviolet radiation would manage to get to Earth, and cause harm to us through burns and skin cancer

Answer 199

... the addition of halogenoalkanes in the atmosphere

Answer 200

OZONE DEPLETION IS NOTHING TO DO WITH GLOBAL WARMING

Answer 201

.Chlorofluorocarbons are a family of organic compounds that contain chlorine atoms and fluorine atoms, examples include dichlorodifluoromethane and 1, 1, 1-trichloro-2, 2, 2-trifluoroethane

Answer 202

... refrigerants, to cool the air inside refrigerators | .They were also found to be useful in other products like aerosol sprays and form fire extinguishers

Answer 203

... they do not react with other substances

Answer 204

... reach the atmosphere they absorb UV radiation from the Sun which breaks their covalent bonds to form highly reactive free radicals

Answer 205

These react very quickly with ozone molecules in a free radical chain reaction

Answer 206

Initiation – .The UV breaks the weaker C-Cl bond within the CFC molecule .CF2Cl2 -> CF2Cl + Cl ● Propagation – .The chlorine radical Cl’ is very reactive and reacts with ozone molecules .Cl ● + O3 -> ClO ● + O2 step 1 .ClO ● + O3 -> Cl ● + 2O2 step 2 .Propagation step 2 regenerates a Cl’ free radical, so the 2 steps repeat in a cycle over and over again

Answer 207

O3 + O --> 2O2

Answer 208

.The effect of CFC’s on the Ozone layer was established in the 1970’s .In 1987, an international agreement called the Montreal Protocol was put in place – it froze the production of CFC’s and agreed to phase out their use from 1990 .Since CFC’s are so stable, it will be many years till they disappear from the atmosphere .Some Ozone depletion has therefore continued since the phasing out of CFC’s

Answer 209

a separating technique that is used to collect a product from an organic synthesis reaction

Answer 210

a technique used in organic synthesis to ensure that a reaction mixture does not boil away

Answer 211

.Pear-shaped flask .Heating mantle .Condenser

Answer 212

1. Mount an iron ring on a clamp stand and put the separating funnel in it. 2. Remove the stopper and make sure that the tap at the bottom is closed. 3. Carefully pour the mixture into the funnel so that the funnel is no more than half full. Wash out the reaction vessel with water and add this to the mixture in the funnel – there should still be some air in the funnel. Put the stopper back. 4. Take the funnel out of the ring and invert it. Open the tap to equalise the pressure. Turn the tap back to closed. Gently shake the mixture in the funnel and equalise the pressure as required. Repeat until you no longer hear a ‘whistle’. 5. Replace the funnel in the iron ring and give the mixture time to separate into layers. 6. Remove the stopper, put a beaker under the spout and open the tap. Collect the lower (water) layer in a beaker. Turn the tap off. As the organic product is in the upper layer, this aqueous layer can be discarded. 7. Using a clean, dry beaker open the tap and collect the desired organic product. 8. Shake the liquid with a small amount of drying agent and pour the final dry product into a clean, dry container.

Answer 213

Inorganic salts such as magnesium sulphate (MgSO4) and calcium chloride (CaCl2) absorb water slowly to become hydrated. The anhydrous salts can be used to dry other chemicals: .Add a few spatulas of the drying agent to the organic product .If the drying agent clumps together, add some more .When the drying agent remains free-moving the organic product is dry .Use gravity filtration and collect the filtrate, which is the dry organic product

Answer 214

the purification of a liquid by performing multiple distillations

Answer 215

For instance, when ethanol is made by fermentation, distillation is used to remove the ethanol from the mixture of water, yeast and any remaining sugar, then the distillate is usually distilled again to purify the ethanol further

Answer 216

Check notes

Answer 217

.Add a few drops of bromine water to the sample and shake | .Bromine water decolourises

Answer 218

Ketones - no change | Aldehydes - orange turns green

Answer 219

Ketones - no change | Aldehydes - dark red precipitate

Answer 220

Ketons - no silver mirror | Aldehydes - silver mirror

Answer 221

effervescence (hydrogen)

Answer 222

effervescence (carbon dioxide)

Answer 223

Sweet smell of an ester after a short time

Answer 224

Paracetamol, aspirin, niacin

Answer 225

The chemical reactivity of each functional group is usually the same as it would be on its own

Answer 226

Aspirin is an analgesic (painkiller) and was original obtained from willow bark. It has a number of functional groups including a carboxylic acid and an aromatic ring

Answer 227

Vitamins help our bodies to work more efficiently. Many vitamins are complex organic molecules with several functional groups. Vitamin B3, also known as niacin, has the IUPAC name pyridine-3-carboxylic acid. It is needed for healthy hair, eyes, skin and liver. This organic molecule contains nitrogen in a stable structure known as a pyridine ring and a carboxylic acid functional group.

Answer 228

check notes

Answer 229

- Identify molecular mass of unknown compounds - Determine the abundance of each isotope in an element - Gain information about the structure and chemical properties of molecules

Answer 230

- Monitor breath of patients during surgery - Detecting banned substances in athletes - Analysing molecules in space - Detecting toxic chemicals in marine life

Answer 231

.Mass spectrometers have been included on-board several space probes .In 2005, the Huygens probe landed on the surface of Titan, the largest moon of Saturn

Answer 232

.During the descent towards the surface of Titan, the mass spectrometer analysed the atmospheric composition at various heights, it was found that the atmosphere consists of mainly nitrogen and methane but the presence of argon-40 was also detected

Answer 233

.Determines the mass of a molecule or isotope by measuring mass to charge ratio of ions

Answer 234

.Sample introduced via a sample inlet .Ionisation of sample by electron impact, chemical ionisation, electrospray or laser .Ions accelerated into mass analyser .Ions separated due to mass-to-charge ratio by deflection from magnetic field or time of flight .Ions detected and spectrum generated by computer

Answer 235

Vaporisation, ionisation, acceleration, deflection, detection

Answer 236

.Vaporization – the sample material is introduced into the spectrometer as a gas, solid samples first need to be heated and vaporized .Ionisation – As the sample vapour passes across the electron beam, high-energy electrons in the beam knock out electrons in the sample atoms, ionizing them into positive ions .Acceleration – an electric field is created using a series of negatively charged plates, the positive ions are attracted towards these plates and accelerated towards an electromagnet .Deflection – the electromagnet creates an electromagnetic field (EMF) that deflects the ions, the amount by which they are deflected depends on their mass to charge ration (m/z) (high m/z deflects a small amount, low m/z deflects a large amount, specific m/z deflected to the collection plate), ions with a specific m/s for a given strength of the EMF are deflected through a slit in a negatively-charged collector plate onto a detector screen .By varying the strength of the EMF, ions with different m/z values can be deflected through a narrow slit and on to the collector plate .Detection – Once ions strike the collector they induce a current, which is amplified and converted into a mass spectrum, the more ions of a particular m/z, the greater the current and the larger the peak

Answer 237

Molecules become ionised and lose an e-, giving a molecule ion M+ C2H5OH + e-  C2H5OH+ + e-

Answer 238

.The mass loss of e- is negligible

Answer 239

.Molecular ion mass = molecular mass of compound

Answer 240

.Molecular ion detected and analysed

Answer 241

.Excess energy from ionisation can be transferred to molecular ion making it vibrate .This can cause bonds to weaken and can split molecular ions into fragments (fragmentation) C2H5OH+  CH3 + CH2OH+

Answer 242

.Although the molecular ion peak for 2 isomers will be the same m/z value, fragmentation patterns will be different .Each organic compound has a unique mass spectroscopy, which can be used as a ‘fingerprint’ for identification

Answer 243

The peak with the highest m/z is formed by the molecular ion, and the value of m/z is equal to the relative molecular mass of the compound .The peak at the highest m/z on the mass spectrum is formed by the heaviest ion that passes through the spectrometer .Unless all molecules of the original substance break up, this corresponds to the molecular ion of the sample substance

Answer 244

... database and a match found which gives identification of an unknown compound

Answer 245

.You will also see a very small peak one unit after the M+ peak, this is referred to as the M+1 peak

Answer 246

.The M+1 peak exists as 1.1% of carbon is present as the carbon-13 isotope, this will mean a small number of molecules have a carbon-13 atom, and hence a mass one unit greater than the Mr (M peak)

Answer 247

((height of M+1 peak)/(height of M peak)) x 100

Answer 248

High resolution mass spectrometry cannot differentiate between structural isomers using the M+ peak alone

Answer 249

Infrared energy

Answer 250

wavelengths

Answer 251

Molecular vibrations

Answer 252

this means that both carbon-hydrogen bonds stretch in time with each other

Answer 253

this means that the carbon-hydrogen bonds stretch out of time with each other

Answer 254

absorbing infrared energy

Answer 255

wavelengths

Answer 256

... the bond has a dipole that changes as it vibrates

Answer 257

.The symmetrical stretch in carbon dioxide does not result in an overall change in dipole of the molecules so no IR energy is transferred to the bonds

Answer 258

.The asymmetrical stretch in carbon dioxide does result in an overall change in dipole of the molecule, so IR energy is transferred to the bonds

Answer 259

.The bending vibration in carbon dioxide does result in an overall change in dipole of the molecule, so IR energy is transferred to the bonds

Answer 260

two absorption due to these vibrations (asymmetrical and bending)

Answer 261

bending or stretching

Answer 262

... spectrometer

Answer 263

- Bond strength - Bond length - Mass of the bonded atoms

Answer 264

.An infrared spectrometer records the frequencies of infrared energy absorbed by a sample

Answer 265

.The sample of solid or liquid is prepared by being pressed between two salt plates, which are transparent to infrared radiation .The sample is placed in the infrared spectrometer and the cover is closed .Infrared radiation is fired at the sample, some frequencies are absorbed, while the remaining frequencies pass through and are registered by the detector on the far side of the sample .The radiation that doesn’t pass through has been absorbed by bonds in the material, causing them to stretch and/or bend, the pattern of frequencies absorbed is unique to the substance being tested .The results of the spectroscopy are plotted on a screen as a graph of percentage transmission of radiation against wavenumber

Answer 266

check notes

Answer 267

A peak (downwards is still a peak) is characteristic of a vibration of a particular group

Answer 268

.At the police station, the motorist blows into a more accurate breathalyzer, containing an IR spectrometer .The breathalyzer calculates the percentage of alcohol in the breath by looking at the size of the absorption due to the C–H bond stretch in the alcohol

Answer 269

to analyse paint fragments from vehicles in hit-and-run offences

Answer 270

- Monitoring the degree of unsaturation in polymers - Quality control in perfume manufacture - Drug analysis

Answer 271

Location: Alcohols, esters, carboxylic acids | Wavenumber (cm-1): 1000-1300

Answer 272

Location: Aldehydes, ketones, carboxylic acids, esters, amides Wavenumber (cm-1): 1640-1750

Answer 273

Location: Organic compounds with a C-H bond | Wavenumber (cm-1): 2850-3100

Answer 274

Location: Carboxylic acids | Wavenumber (cm-1): 2500-3300 (very broad)

Answer 275

Location: Amines, amides | Wavenumber (cm-1): 3200-3500

Answer 276

Location: Alcohols, phenols | Wavenumber (cm-1): 3200-3550 (broad)

Answer 277

* O-H (hydroxyl) group for alcohols * C=O (carbonyl) group for aldehydes and ketones * COOH (carboxyl) group in carboxylic acids

Answer 278

.An infrared spectrum is a plot of transmission of infrared radiation against wavenumber

Answer 279

1/wavelength

Answer 280

.Any wavelength that is absorbed by the sample will transmit less than the others, forming a dip or ‘peak’ in he graph

Answer 281

.Peaks at different wavenumbers identify different functional groups

Answer 282

.The region below 1500cm-1, usually called the fingerprint region, has many peaks that are difficult to assign .The pattern of these peaks is unique to a particular compound

Answer 283

.A substance may be identified by comparing the IR spectrum to a database of reference spectra .An exact match in the fingerprint region identifies a compound

Topic 4 - Core Organic Chemistry Flashcards

(356 cards)