Lecture Notes for CM2010 and CM2101 2024 2025 Flashcards
What did the late 18th century suggest about organic compounds?
Compounds from living organisms were considered organic, while those from lifeless matter were considered inorganic.
Who discredited the concept of ‘vital force’ and how?
Wöhler discredited the concept by synthesizing urea from ammonium cyanate.
What is the empirical formula of lactic acid (C3H6O3)?
CH2O
What are the main elements that compose the majority of organic substances?
Carbon, Hydrogen, and maybe other elements.
What does the concept of molecules involve?
Atoms of Carbon and other elements connected by covalent bonds.
What is Bond Dissociation Energy for Carbon-Carbon bonds?
348 kJ mol-1
What is unique about Carbon in organic chemistry?
Carbon can catenate, forming chains of atoms.
Define organic molecules.
Carbon-based molecules.
What defines organic chemistry?
Chemistry of carbon-based molecules.
List some properties of organic molecules.
- Stability due to C-C covalent bonds
- Defined molecular structures
- Defined three-dimensional shapes
Give examples of organic chemicals.
- DNA
- Foodstuffs
- Medicines
- Active Pharmaceutical Ingredients
- Excipients
- Fuels
- Materials
What are Active Pharmaceutical Ingredients (APIs)?
Typically organic molecules of molecular weight < 1000 g/mol.
What is the significance of Cork in pharmaceuticals?
Cork is a world hub for Pharma.
What are the stages of pharmaceutical development?
- Lead Discovery
- Pre-Clinical Development
- Phase I & II Clinical Trials
- Phase III Clinical Trials
- Launch & Manufacture
What are the aspects of organic molecules?
- Structure & bonding
- 3D shape (Stereochemistry)
- Naming (Nomenclature)
- Physical properties
- Chemical properties
- Reactions
- Mechanism
What is a Functional Group?
The part of a molecule that determines its chemistry and biological profile.
List examples of functional groups.
- Alkanes
- Ketones
- Amines
Identify the first five alkanes by their number of carbon atoms.
- 1C: methane
- 2C: ethane
- 3C: propane
- 4C: butane
- 5C: pentane
What is the empirical formula of ethane?
CH3
What is the molecular formula of ethane?
C2H6
What is the bond angle formed by bonds to a carbon atom in ethane?
Approximately 109.5°
What does hybridization refer to in organic chemistry?
The modification of atomic orbitals to form molecular orbitals.
What is the total number of atomic orbitals involved in forming ethane?
14 (from 2 Carbons and 6 Hydrogens)
What are the types of molecular orbitals formed in ethane?
- 7 Bonding molecular orbitals
- 7 Anti-bonding molecular orbitals
What is the significance of molecular orbital theory (MOT)?
It helps to model molecules and predict their properties.
True or False: All ethane molecules are planar.
False
How many total atomic orbitals are contributed by hydrogens in ethane?
14
How many molecular orbitals does ethane have?
14
What types of molecular orbitals are present in ethane?
- 7 Bonding molecular orbitals
- 7 Anti-bonding molecular orbitals
What is the geometry of carbon in ethane?
Tetrahedral
What hybridization does carbon undergo in ethane?
sp3
What is the tetrahedral angle in ethane?
Approximately 109.5 degrees
What is a Newman projection used for?
To define a dihedral angle or torsional angle (φ)
What is the torsional angle (φ) in the staggered conformation of ethane?
60 degrees
What is the maximum energy conformation of ethane?
Eclipsed conformation
What is steric hindrance?
Unfavorable interaction between groups which are close together in space
What is the energy difference between eclipsed and staggered conformations of ethane?
12 kJ mol-1
What type of bonds does ethane contain?
- C-C single bonds
- C-H single bonds
What is the general formula for alkanes?
C_nH_{2n+2}
What are the first five alkanes and their molecular formulas?
- Methane: CH4
- Ethane: C2H6
- Propane: C3H8
- Butane: C4H10
- Pentane: C5H12
What suffix indicates that a compound is an alkane?
…ane
What is the significance of the prefix in alkane nomenclature?
Indicates the number of carbons in the compound
What type of structural formula provides information on atom-to-atom connectivity?
Structural formula
What is the most stable conformation for simple alkanes at room temperature?
All staggered ‘straight chain’ conformation
What are structural isomers?
Same molecular formulae, different structural formulae
How many structural isomers does pentane (C5H12) have?
3
What is the concept of a homologous series in organic chemistry?
A series generated by repeatedly adding ‘CH2’ to the previous member
What type of compounds are called straight chain?
Compounds without branches
What is an example of a branched alkane?
Isobutane (C4H10)
What is the significance of the torsional angle in molecular conformations?
It indicates the degree of rotation about a bond
True or False: Ethane contains only sp2 hybridized carbon.
False
What are compounds without branches called?
Straight chain
How are branched compounds named?
As alkyl derivatives of the longest straight chain in the molecule
What determines the parent name in alkane nomenclature?
The length of the longest chain
What is the purpose of numbering the straight chain in an alkane?
To indicate the point of branching
List the first four alkanes.
- Methane
- Ethane
- Propane
- Butane
What is the structure of 2-Methylbutane?
A straight chain numbered to give the lower branch number
What are identical substituents grouped with in nomenclature?
‘di…’ for two, ‘tri…’ for three, ‘tetra…’ for four
What is the general formula for cycloalkanes?
C_nH_{2n}
Which cycloalkane has a planar structure?
Cyclopropane
What causes angle strain in cyclopropane?
Bond angles approaching 60°
Which cycloalkane has almost zero angle strain?
Cyclopentane
What structural form does cyclohexane adopt to reduce strain?
Chair conformation
At what temperature can two different types of hydrogen environments be observed in cyclohexane?
Below 230 K (-43 °C)
What is the energy barrier to ring inversion in cyclohexane?
43 kJ mol^-1
What happens to cyclohexane at temperatures above 230 K?
Only one hydrogen environment is observed
What is the effect of replacing a hydrogen in cyclohexane with a methyl group?
The two chair conformations are no longer equivalent
What are the steric interactions called between an axial methyl group and 1,3-diaxial hydrogens?
1,3-diaxial interactions
What is the main source of alkanes with lower molecular weights (less than 5 carbons)?
Natural gas
What type of intermolecular forces are present in alkanes?
London dispersion forces
How do alkanes behave in water?
Insoluble; they are hydrophobic
What defines unsaturated hydrocarbons?
Contain Carbon-Carbon multiple bonds
What are alkenes characterized by?
Presence of Carbon-Carbon double bonds
What is the older name for alkenes?
Olefins
What is the general structural formula for alkenes?
RRC=CRR
What is the bond angle about each carbon in alkenes?
~120°
What hybridization is not able to provide the geometry found at carbon in carbon-carbon double bonds?
sp3 hybridization
What is the hybridization of alkenes?
sp²
Alkenes cannot provide the geometry found at Carbon in Carbon-Carbon double bonds.
What is the bond angle around sp² hybridized Carbon?
Approximately 120°
This angle is consistent with trigonal planar geometry.
What type of bond is formed by the overlap of two sp² hybridized orbitals?
σ bond
An antibonding orbital is also formed but is not occupied by electrons.
What results from the overlap of pz orbitals in alkenes?
π bond
An antibonding π orbital is also formed but is not occupied by electrons.
What is the structure of the Carbon-Carbon double bond?
One σ bond and one π bond
Both bonds are occupied by two electrons.
What is required for rotation about a Carbon-Carbon double bond?
Large input of energy (~268 kJ mol⁻¹)
This energy requirement prevents rotation at room temperature.
What is Cis-Trans isomerism?
Isomerism due to different spatial arrangements of groups around a double bond
The cis isomer has similar groups on the same side, while the trans isomer has them on opposite sides.
What is the first member of the alkene series?
Ethene (Ethylene)
Chemical formula: C₂H₄.
What is the second member of the alkene series?
Propene (Propylene)
Chemical formula: C₃H₆.
What does the suffix ‘…ene’ indicate in alkene nomenclature?
Presence of a Carbon-Carbon double bond
The prefix indicates the number of carbons.
What are structural isomers?
Compounds with the same molecular formula but different arrangements of atoms
Example: 1-Butene and 2-Butene.
What is the boiling point of cis-2-butene?
0.3°C
The melting point is -106°C.
What is the boiling point of trans-2-butene?
3.7°C
The melting point is -139°C.
What type of hybridization do alkynes exhibit?
sp
Alkynes are characterized by the presence of Carbon-Carbon triple bonds.
What is the general structure of alkynes?
R-C≡C-R
The groups R and C are co-linear.
What is the bond structure of a triple bond in alkynes?
One σ bond and two π bonds
The σ bond forms from sp hybrid orbital overlap, and the π bonds form from p orbital overlap.
What is the first member of the alkyne series?
Ethyne (Acetylene)
Chemical formula: C₂H₂.
What is the second member of the alkyne series?
Propyne
Chemical formula: C₃H₄.
What are nucleophiles?
Electron pair donating species
They react with electrophiles to form new covalent bonds.
What are electrophiles?
Electron pair accepting species
They react with nucleophiles in bond formation.
What is the order of stability for carbocations?
Tertiary > Secondary > Primary
This stability is due to the inductive effect of alkyl substituents.
What is the smallest stable cycloalkyne?
Cyclononyne
Cyclononyne is the smallest stable cycloalkyne.
What is the structure and molecular formula of benzene?
6-membered ring system, C6H6
Benzene has a unique structure that contributes to its stability.
How do the C-C bond lengths in benzene compare to those in alkenes?
C-C bonds in benzene are 139 pm, while C-C in alkenes are 154 pm and C=C are 134 pm
The equal bond lengths in benzene contribute to its aromatic stability.
What hybridization do the carbons in benzene exhibit?
sp2 hybridised
The sp2 hybridization allows for planar geometry and overlap of p orbitals.
What concept describes the stability of benzene’s electron system?
Aromaticity
Aromatic systems like benzene are especially stable due to resonance delocalization of electrons.
What are resonance forms in the context of benzene?
Structures that contribute equally to the overall bonding system
These structures help explain the delocalization of electrons in benzene.
What is the general structure of organic halogen compounds?
R-X, where X = Cl, Br, I, F
Organic halogen compounds are important in synthetic chemistry.
How are alkyl halides classified?
Based on the degree of substitution: primary, secondary, tertiary
The classification affects their reactivity and properties.
What is the molecular formula for ethanol?
C2H5OH
Ethanol is produced through fermentation or hydration of ethylene.
What is the difference between absolute alcohol and commercial ethanol?
Absolute alcohol is purified using CaO to remove water
Commercial ethanol typically contains 5% water.
What classifies alcohols as weak acids?
R-OH can donate a proton
The acidity of alcohols can be compared with that of phenols.
Define the carbonyl group.
C=O functional group
The carbonyl group is a significant functional group in organic chemistry.
What are the key differences in nomenclature between aldehydes and ketones?
Aldehydes use ‘al’ suffix, ketones use ‘one’ suffix
This distinction helps in identifying the type of carbonyl compound.
What is the boiling point of acetaldehyde?
20°C
Acetaldehyde can be prepared from ethylene through the Wacker process.
What are the common carboxylic acids mentioned?
- Formic acid (methanoic)
- Acetic acid (ethanoic)
Carboxylic acids are important in various biochemical processes.
What are the classifications of amines?
Primary (1°), Secondary (2°), Tertiary (3°)
The classification is based on the number of carbon substituents attached to the nitrogen atom.
What is an example of a naturally occurring amine?
Caffeine
Other examples include nicotine and cocaine.
What is the general formula for esters?
RCOOR’
Esters are formed from the reaction of an alcohol and a carboxylic acid.
What is the significance of the bond dipole in alcohols?
It influences boiling points and solubility
The electronegativity difference between oxygen and hydrogen creates a bond dipole.
What is the reactivity of aldehydes and ketones influenced by?
The nature of substituents on the carbonyl group
Different substituents can significantly alter the properties and reactivity of these carbonyl compounds.
What is the alternative name for aminopentane?
2-pentanamine
What is the structure of 1-methylaminopropane?
CH3NHCH2CH2CH3
When other functional groups are present, how is the amino group named?
As a substituent
What is the name of the compound with the structure CH3CH(CH2)C(OH)NH2?
3-aminobutanoic acid
What is the common name for 4-bromoaniline?
An aromatic amine
What is N,N-dimethylaniline categorized as?
An aromatic amine
What is Beloranib used for?
Treatment of obesity
What type of drug is Furosemide?
A loop diuretic
What conditions is Furosemide used to treat?
Congestive heart failure and edema
What is Taxol (Paclitaxel) approved for in the UK?
Ovarian, breast, lung, bladder, prostate, melanoma, esophageal, and other types of solid tumor cancers
What type of compound is Taxol (Paclitaxel)?
An ester
Fill in the blank: How many other Functional Groups can you spot? _______
[key learning term]
