S3.2 Flashcards
(120 cards)
1
Q
what kind of bonding is in typical organic compounds
A
molecular covalent networks
2
Q
saturated vs unsaturated organic compounds
A
- saturated ⇒ only single covalent bonds
- unsaturated ⇒ contain at least one or more double or triple carbon-carbon bonds
3
Q
why is carbon so special?
A
forms 4 covalent bonds
can be catenated (bonds to atoms of the same element in a series)
can be hybridized
4
Q
primary, secondary, tertiary, quartenary carbon
A
Primary (1°) carbon ⇒ bonded to 1 other carbon atom
Secondary (2°) carbon ⇒ bonded to 2 other carbon atoms
Tertiary (3°) carbon ⇒ bonded to 3 other carbon atoms
Quaternary (4°) carbon ⇒ bonded to 4 other carbon atoms
5
Q
division of hydrocarbons
A
aliphatic => acyclic, cyclic
aromatic
6
Q
detection of C and H
A
complete oxidation: organic compound → (with heat, CuO – strong oxidizing agent) CO2(g) + H2O(g)
CO2 is tested with the limewater (Ca(OH)2) test: CO2 is present ⇒ precipitate forms due to the formation of CaCO3 and H2O
H2O is tested by the anhydrous copper sulfate test: copper sulfate becomes hydrated ⇒ turns blue if water is present
7
Q
detection of halogens
A
conversion to water-soluble ionic compounds => reduced (usually with Na) => adding AgNO3 ⇒ appearance of a precipitate AgX ⇒
white precipitate: AgCl
yellowish: AgBr
intense yellow: AgI
AgF does not form a precipitate
8
Q
detection of CN¯
A
conversion to water-soluble ionic compounds => reduced (usually with Na) => adding FeSO4 and FeCl3 => Prussian blue colour due to the presence of Fe4[Fe(CN)6]3
9
Q
detection of SCN¯
A
conversion to water-soluble ionic compounds => reduced (usually with Na) => adding FeCl3 => blood-like colour (deep red) due to the presence of [Fe(SCN)3]
10
Q
detection of S(2-)
A
conversion to water-soluble ionic compounds => reduced (usually with Na) => adding Pb(CH3COOH) ⇒ black precipitate PbS
11
Q
detection of alcohols
A
alcohol + Na => hydrogen gas
12
Q
Beilstein test
A
copper oxide reacts with a halogen to form CuX2, which when burned gives off a blue-green light
not selective, positive result should be otherwise confirmed
13
Q
formulas of organic compounds
A
- Empirical formula ⇒ smallest whole number ratio of atoms in a compound
- Molecular formula ⇒ true number of atoms in a compound
- Structural ⇒ present all bonds and atoms in a compound (does not reflect bond angles)
- Condensed ⇒ structural, excluding bonds with H
- Skeletal ⇒ each line represents a single C-C bond, excludes H bonded to C, heteroatoms are written, H bonded to a heteroatom is written together
- Stereochemical formula ⇒ projects the three-dimensional structure of a molecule onto a plane, represents the shape of the molecule (dash and wedge notation)
14
Q
homologous series
A
a series of compounds that have the same functional group, and each member differs from the next member by a –CH2– unit in their formulas
15
Q
alkane homologous series
A
CnH2n+2
16
Q
alkene homologous series
A
CnH2n
17
Q
alkyne homologous series
A
CnH2n-2
18
Q
physical trends in homologous series
A
- longer carbon chain (or greater molecular mass): greater density, greater the attractive force between molecules ⇒ higher melting point, boiling point
- more branched ⇒ less surface area ⇒ weaker LDFs ⇒ less energy required for separation
19
Q
suffix for alkanes, classification
A
-ane
no functional group, only single bonds
20
Q
suffix for alkenes
A
alkene
21
Q
suffix for alkynes
A
-yne
22
Q
aromatic compound as a side chain
A
phenyl group
23
Q
naming an org. comp. with a halogen
A
haloalkane
halo/chloro/bromo/iodo/fluoro-
24
Q
division of haloalkanes
A
primary ⇒ 1 carbon atom directly attached to the carbon bearing the halogen
secondary ⇒ 2 carbon atoms directly attached to the carbon bearing the halogen
tertiary ⇒ 3 carbon atoms directly attached to the carbon bearing the halogen
25
alcohol functional group, position
hydroxyl (OH-) at the end of a chain
26
naming alcohols
-ol or hydroxy-
hydroxy- is used in the presence of higher precedence functional groups
27
division of alcohols
primary alcohol ⇒ 1 carbon atom directly attached to the carbon bearing the hydroxyl group
secondary alcohol ⇒ 2 carbon atoms directly attached to the carbon bearing the hydroxyl group
tertiary alcohol ⇒ 3 carbon atoms directly attached to the carbon bearing the hydroxyl group
28
ether functional group, position
oxy group (oxygen bonded to two alkyl groups)
oxygen in the middle of a chain
29
naming of ethers
smaller/less important chain -oxy- important chain
30
aldehyde functional group, position
carbonyl group (carbon double bonded to oxygen) at the end of a chain
31
naming of aldehydes
-al, oxo-, -carbaldehyde, formyl-
* oxo- is used in the presence of higher precedence functional groups
* aldehyde is attached to a ring ⇒ -carbaldehyde
* molecule contains a higher-priority functional group ⇒ formyl-
32
ketone functional group, position
carbonyl group (carbon double bonded to oxygen) in the middle of a chain
33
ketone naming
-one, oxo-
oxo- is used in the presence of higher precedence functional groups
34
carboxylic acid functional group, position
carboxyl group (carbon double bonded to O and bonded to OH) at the end of the chain
35
naming carboxylic acids
-oic acid, -carboxylic acid
carboxyl group on the cyclic structure ⇒ -carboxylic acid
36
ester functional group, position
carboxyl group (carbon double bonded to O and bonded to O) in the middle of the chain
37
ester naming
first part + second-oate
38
acid anhydride functional group, position
acid anhydride group (two carbons double bonded to oxygens, then single bonded to the same oxygen) in the middle of the chain
39
acid anhydride naming
-oic anhydride
40
acyl halide functional group, position
acyl halide group (carbon double bonded to oxygen and single bonded to a halogen) at the end of a chain
41
naming acyl halides
-oyl halide
42
amine functional group
amino group (nitrogen bonded to 3 atoms)
43
naming amines
-amine
44
division of amines
primary ⇒ 1 carbon atom directly attached to the carbon bearing the amine group
secondary ⇒ 2 carbon atoms directly attached to the carbon bearing the amine group
tertiary ⇒ 3 carbon atoms directly attached to the carbon bearing the amine group
45
amide functional group
amide group (nitrogen bonded to a carbon, double bonded to an O and two more groups)
46
amide naming
-amide
47
nitrile functional group
nitrile group (nitrogen triple bonded to a carbon)
48
naming nitriles
-nitrile
49
naming of benzene + OH
phenol
50
benzene as a side chain
phenyl-
51
order of precedence of functional groups
1. carboxyl group (-COOH)
1. aldehydes (-COH)
1. ketones (=C=O)
1. hydroxyl (-OH)
1. amine (-NH2)
1. -ane/ene/yne
1. alkyl groups, halogens
52
isomers def
compounds with the same molecular formula, but different structure
53
division of isomerism
1. **structural** isomerism ⇒ chain isomerism, position isomerism, functional group isomerism
1. **stereoisomerism** ⇒ geometrical (cis-trans), optical, conformational
54
structural isomerism def and types
= same molecular formula but different structural formulae
1. Chain isomerism ⇒ different lengths of the parent chain
1. Position isomerism ⇒ functional/alkyl group is in a different position
1. Functional group isomerism ⇒ different functional group
55
chain isomerism
| def, more general isomerism type
different lengths of the parent chain
structural isomerism
56
position isomerism
| def, more general isomerism type
functional/alkyl group is in a different position
structural isomerism
57
functional group isomerism
| def, more general isomerism type
different functional group
ether — alcohol
carboxylic acid — ester
ketone — aldehyde
58
stereoisomerism def, types
same molecular formula but atoms occupy different positions in space
1. **Geometrical (cis-trans) isomerism** ⇒ alignment of functional groups in relation to a C=C bond
1. **Optical isomerism** ⇒ same connectivity but different spatial arrangement
1. **Conformational** ⇒ different spatial arrangements of the same molecule that arise due to free rotation around a single (σ) bond
59
geometric (cis-trans) isomerism
| def, type of isomerism
stereoisomerism
alignment of functional groups in relation to a C=C bond, due to the restricted rotation in a molecule from a C=C bond or a ring structure
60
cis vs trans isomer
cis isomer ⇒ functional groups on the same side of the C=C bond
trans isomer ⇒ functional groups on opposite sides of the C=C bond
61
optical isomerism
| def, type of isomerism
stereoisomerism
⇒ same connectivity but different spatial arrangement in relation to a chiral center creating non-superimposable molecules
62
non-superimposable ⇒ ?
two substances can be distinguished as differences exist when laid directly over each other
63
chirality, chiral carbon
the property of a molecule that results in non-superimposable mirror images => carbon atom that is bonded to four different atoms or groups of atoms
64
optical activity
compounds that contain a chiral carbon atom ⇒ optically active, rotates plane-polarised light
compound that does not contain a chiral carbon atom ⇒ optically inactive, has no effect on the rotation of plane-polarised ligh
65
enantiomer
a pair of stereoisomers that are non-superimposable mirror images of each other
66
number of enantiomers
2^n, where n = number of chiral carbon atoms
67
distinguishing enantiomers
the difference in their interaction with plane-polarised light
rotate it by the same angle, but in different directions
68
plane-polarised light
light that has passed through a polarising filter and only oscillates in one direction
69
operation of a polarimeter
1. Unpolarised light is passed through a polarising filter ⇒ **plane-polarised light**
1. The plane-polarised light passes through a **solution** containing the enantiomer ⇒ light is rotated either **clockwise** (dextro; A(+)) or **anti-clockwise** (levo; A(–))
1. The **analyser** measures the angle and direction of rotation of the plane-polarised light
70
Biot’s law
ɑ = [ɑ] l c
ɑ … observed optical rotation [°]
[ɑ] … specific rotation
l … length of the cell [dm]
c … sample concentration [g/mL]
71
racemic mixture, racemate
optically inactive (due to no net light rotation solution that contains equal amounts of two enantiomers
72
physical and chemical properties of stereoisomers
physical: identical apart from their interaction with plane-polarised light
chemical: similar chemical properties, except for interactions with other chiral molecules
73
R and S isomers
prioritize the 4 groups (higher M ⇒ higher priority)
lowest priority is pointing away
order of remaining ⇒ clockwise (⇒ R-name of compound), anti-clockwise (⇒ S-name of compound)
74
D and L isomers
functional group (-OH, NH2) is on the right ⇒ D-isomer
on the left ⇒ L-isomer
75
conformational isomerism
| def, type of isomerism
stereoisomerism
different spatial arrangements of the same molecule that arise due to free rotation around a single (σ) bond => no change in connectivity, only spatial arrangement
different conformations have different energies due to steric hindrance and torsional strain (farther away => more stable, lower in energy)
76
method of synthesizing smaller organic compounds from larger ones
fractional distillation (separation of different liquids based on boiling points with very similar bp) ⇒ products are gaseous products, gasoline, kerosine, diesel, oil, asphalt, …
77
steps in the fractional distillation of crude oil
1. crude oil is heated and most of it evaporates
1. it enters the fractionating column as a gas
1. the crude oil fractions cool and condense out at different levels, depending on their boiling points
78
crude oil fractions
1. lubricating oil, wax, asphalt
2. fuel oil
3. diesel
4. kerosene
5. petrol
6. butane, propane, methane
79
catalytic converters
transition metals are catalysts of toxic gasses (coming from combustion) into less harmful gasses (CO2, N2, H2O)
80
biofuels pros and cons
- smaller carbon footprint than fossil fuels in consumption
- biofuel crop production requires large amounts of both oil and water resources
- similar in environmental impact to fossil fuels
| fuel derived immediately from living matter
81
fossil fuel pros and cons
- can generate a large amount of electricity
- cost-effective
- easy transportation
- available
- pollutant, release large amounts of carbon dioxide, a greenhouse gas, into the air
82
increasing size of a non-polar part of an alcohol => solubility of alcohols
decreases
83
H-bond donor vs acceptor
H-bond donor = a hydrogen atom bonded to a highly electronegative atom (like N, O, F)
H-bond acceptor = a lone pair on a highly electronegative atom (like O, N, F)
84
spectroscopy def
an analytical technique which helps to determine the molecular structure of org compounds
85
types of spectroscopy
1. IR
2. MS
3. HNMR (proton nuclear magnetic resonance)
4. UV-Vis spectroscopy
5. Microwave
86
IR spectroscopy main task and how it basically works
* measures the bond vibration frequencies in a molecule and is used to determine the functional groups and bonding types present in a molecule
* IR is absorbed by molecules by creating vibrations ⇒ different signals which are specific to distinct molecules and bonding types => detection of different functional groups
87
vibrational modes of molecules
1. stretching (bond angles remain): symmetric, asymmetric
2. bending (bond angles change): in plane, out of plane
88
IR spectrum
| axes
waver number (x-axis; usually from greatest value to lowest) and transmittance (y-axis)
89
wave number
reciprocal of wavelength in cm ⇒ proportional to energy and frequency
90
higher absorbance of a wavelength ⇒ transmittance?
lower transmittance
91
FT-IR: what it is, advantages, what it is used for, core component (+ how it works)
* IR with an interferometer
* advantages: faster, more sensitive, less energy required, averages several scans, instrument is kept accurately calibrated
* for liquids and solids
* ATR (attenuated total reflection) crystal
* IR passes through an ATR (attenuated total reflection) crystal so that it reflects at least once off the internal surface in contact with the sample ⇒ the reflection forms the evanescent wave, which extends a few microns into the sample ⇒ sample absorbs specific frequencies of the evanescent wave corresponding to molecular vibrations, thereby weakening the reflected IR beam at those frequencies
92
frequency of vibration depends on:
1. **masses of atoms** in a bond: greater atomic weight ⇒ smaller frequency
2. **bond enthalpy**: greater bond enthalpy ⇒ stronger bond ⇒ greater frequency
93
which compounds have the same IR spectrum?
only enantiomers
94
fingerprint region in IR
complex vibrations (600-1400 cm-1) ⇒ unique for any compound (don’t look much into it)
95
stronger bonds absorb IR at lower or higher frequencies?
higher
96
conjugation of double bonds on absorption frequencies
conjugation of double bonds lowers absorption frequencies ⇒ absorption frequencies of isolated C=C > conjugated > aromatic
97
different C-H stretching
more s character ⇒ absorbs at a higher frequency ⇒ sp3 (below 3000 cm-1 to the right) > sp2 (below 3000 cm-1 to the left) > sp
98
which bonds are IR active?
polar bonds are IR active: net dipole moment ⇒ vibrations can change it ⇒ bond can stretch/bend ⇒ IR active
nonpolar/symmetrical bonds absorb weakly or not at all: vibrations cannot change it (even with vibrations the dipole stays symmetric and IR cannot be absorbed)cannot stretch, no peak can be observed
no dipole moment but many electrons ⇒ stretching and bending are possible
99
O-H and N-H stretching on IR spectrum
| wavenumber, alcohol, primary amine, secondary, tertiary
* 3300 cm^-1
* alcohol ⇒ broad, round tip
* primary amine ⇒ broad with two sharp spikes
* secondary amine ⇒ broad with one sharp spike
* tertiary amine ⇒ no signal
100
carbonyl stretch (C=O) on IR spectrum
* ketones, aldehydes, carboxylic acid
* carboxylic acid ⇒ C=O and O-H
* aldehydes ⇒ two C-H signals
* closer to the fingerprint region, sharp spike (strongest signal)
101
nitrile group on IR
sharp spike around 2250 cm^-1
102
strengths of IR spectrometry
* functional group is usually indicated
* absence of a signal is definite proof that the functional group is absent
* correspondence with a known sample’s IR spectrum confirms the identity of the compound
103
limitations of IR
* IR alone cannot determine a structure ⇒ must be used in conjunction with information derived from other analytical techniques
* some signals may be ambiguous
104
mass spectrometry
fragmentation of the molecule and measures the masses
masses of fragments and their **relative abundance** reveal information about the structure of the molecule
105
steps in MS
| +more details on ionization
1. **Vaporization** ⇒ substance is vaporised to produce gaseous molecules in order to create a lot of space between atoms and therefore neglect intermolecular forces
1. **Ionization** with a **high energy beam of electrons** ⇒ molecule is fragmented by **electrons being dislodged from a bond**, creating **radicals** (positive charged electrons are deflected, negative charged are not)
1. **Acceleration** ⇒ gaseous ions are accelerated in an electric field
1. **Deflection** ⇒ gaseous ions are deflected by an electromagnet, the degree of this deflection depends on the mass-to-charge ratios of these ions
2. **Detection** ⇒ gaseous ions are detected and a mass spectrum (graph) is produced
106
mass spectrum
mass of fragments (m/z; x-axis), abundance (y-axis)
107
relative atomic mass of an atom from MS
= (rel.ab.1 x mass1) + (rel.ab.2 x mass2) + …
108
GC-MS
gas chromatography mass spec
a mixture of compounds is separated by gas chromatography, then identified by mass spectrometry
109
peaks in MS
base peak (strongest, aka most common fragment) is defined to be 100% => all other peaks are relative to it, most stable carbocation
rightmost peak is the peak of the molecular ion (peak with the highest mass) ⇒ reveals the molecular mass of the compound
110
molecular ion def
ion produced when the molecule is ionised by loss of an electron from the molecule
molecule → molecule+ᐧ + e¯ (molecule+ᐧ is the molecular ion)
111
anomaly of alcohol molecular ion peak
M+ may not be visible since the molecular ion is highly unstable and would rather lose a molecule of water
111
UV-Vis spectroscopy
* measures the **amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample** in comparison to a reference or blank sample to determine bonding patterns and concentrations
* based on the absorption of light: electrons in different bonding environments in a substance require a different specific amount of **energy to promote the electrons to a higher energy state** ⇒ absorption of light occurs for **different wavelengths** in different substances ⇒ insight into composition
112
setup of UV-vis
| +spectrum
light source → light passes through a wavelength selector (filter, monochromator), through sample and then detector → spectrum: absorbance (y-axis), wavelength (x-axis)
113
transmittance calculation
T = I : Io
| I ... output light
Io ... incident light
114
absorbance calculation
A = log10 (Io : I) = log10 (T^-1)
Beer-Lambert law: A = εlc
115
effect of light at frequency of X-ray
ionization
116
effect of light at frequency of UV
electronic transitions
117
effect of light at frequency of IR
molecular vibrations
118
effect of light at frequency of microwave
rotational motion
119
effect of light at frequency of radio waves
nuclear spin transitions
