Wk 5: Organic Compounds Flashcards
Why is carbon the central biological element?
- Valency of 4
- Ability to form long chains (framework for structure and stability)
- Oxide must not be too much more stable than pure element
- Bond to H must be quite strong, compared to H-O
What are hydrocarbons
- H and C molecules
- non-polar (insoluble in H2O)
What are aliphatic and aromatic compounds
- Aliphatic
- Carbon atoms form non-cyclic chains, branched chains and non-aromatic rings
- Aromatic
- unsaturated
- one or more planar rings
- 3 conjugated double bonds
- delocalised pi-electrons
What is a functional group?
- Specialised groups of atoms in a specific bonding arrangement, attached to a simple framework
- Responsible for characteristic chemical reactions of molecules
- Enhance physical and chemical properties of organic compounds
- Normally contain O or N
What are families of organic compounds?
- clustered on basis of structural functional groups
- have the same functional group, but different carbon frameworks
Saturated vs unsaturated
Saturated: Composed entirely of single bonds and saturated with hydrogen
Unsaturated: 1+ double/triple bonds between C atoms
Alkanes
- Saturated
- Functional group
- C-C and C-H (single bonds)
- General formula
- CnH2n+2
What is an alkyl group?
- Alkane with one less hydrogen atom
- Used to attach to another group/atom
- “R” is used to indicate any generic alkyl group
What are alkenes?
- General formula: CnH2n
- Unsaturated
- Functional group: C=C
Biomolecule examples of alkenes
- Limonene, pinene, myrcene (scented plant oils)
- Geranoil (roses, used in perfumes)
- Ethene (plant hormone that triggers ripening)
- Vitamin A
Aromatic hydrocarbons
- Contains a benzene ring
- Aryl group: functional group containing aromatic group
- Phenyl group: specific aryl group derived from benzene -1 H atom
Aromatic hydrocarbons as biomolecules
- Flavouring and spices
- Sex hormones
- Aspirin
- Aromatic amino acids
- Adrenaline
Effects of functional groups on properties of organic molecules
- Increase in molecular interactions
- More energy required to seperate molecules
- higher MP and BP than parent hydrocarbon skeleton
- Increased solubility in polar solvents (like water)
- Increased ability to from H bonds with water
- Higher solubility
- O or N atoms promote H bond formation
Properties of Alcohols
- Formula: ROH
- Functional group: hydroxyl (O-H)
- Naming: remove -e from parent alkane and ad -ol
What is an isomer?
- Same molecular formula, different chemical structure
- Different arrangment of atoms in space
- Do not necessarily share similar chemical/physical properties
Types of alcohols
Primary: 1 R group on C
Secondary: 2 R group on C
Tertiary: 3 R group on C
Physical properties of alcohols
- Electronegative O in hydroxyl group = alcohols are POLAR
- Chain length increases, becomes less soluble
- Alkyl chain length increases, BP increases
What are ethers
- Generic formula: ROR’
- Functional group: Alkoxy (O atom and alkyl group)
- Short chains are soluble in water, but fewer molecular interaction
- Hence lower MP’s than corresponding alcohols
- Naming: alkoxyalkane
- Shorter of 2 chains becomes 1st part of name with -oxy instead of -ane
- Longer alkane chain becomes suffix for the end of the ether
Describe aldehydes and ketones
- Generic Formula:
- Aldehydes: RCHO
- Ketones: RCOR’
- Carbonyl group: O and double bond
- Allows polarisation and H bond formation
- Double bond increases reactivity
- Carbonyl group attachment
- Aldehyde: attached to 1 carbon atom
- Ketone: attached to 2 C atoms (often 2 alkyl groups)
- Naming
- Aldehyde: -al
- Ketone: -one
Aldehydes and ketones in biomolecules
- Glucose: aldose sugar
- Carbonyl group at end of the chain
- Fructose: ketose sugar
- Carbonyl group in middle of chain
- Spices and flavourings
- Almond, cinnamon, mint
