Zusammenfassung der Ressource
Organic Synthesis
- HSW:Artificial Sweeteners
- Sweetness with few calories
- The first - Saccharin (benzoic sulfinide)
- Unstable when heated
- Does not react chemically with other food ingredients
- Stores well
- Unlike sucrose, it has no energy value
- Calorie free
- Fahlberg and Remsen
- High doses → bad health?
- Cyclamate
- Discovered accidentally by Sveda
- Not as sweet as saccharin but does not leave aftertaste
- Sodium or calcium salt of cyclamic acid
- Prepared by sulfonation of cyclohexylamine
- Cyclohexylamine it believed to be toxic in animals
- Aspartame
- Dipeptide of phenylalanine and aspartic acid
- 1965 Schlatter
- 200 times sweeter than sucrose and dissolves readily in water
- Tends to interact with other chemicals in food
- Decomposes hen heated strongly
- Bacterial Fermentation, Synthesis, Purification
- Identifying organic molecules for synthesis
- Sensitive chemical analysis
- Step by Step
- Consider toxic, hazardous compounds
- Consider optical isomers: stereo-selectivity
- Quantitative methods
- % of elements
- Combustion analysis: % C,H
- Empirical formula
- Mass spectrometer → RMM → Molecular formula
- Characteristic reactions of
functional groups
Anlagen:
- Modern techniques
- IR spectroscopy
- Functional groups
- Mass spectrometry
- RMM
- Ion fragments → possible groups
- Nuclear Magnetic Resonance (NMR)
- Groups of H atoms
- Difficult, more steps →
more difficult
- Predicting properties of organic
compounds
- Physical
- Isomers
- Functional group
→ H bond → ↑
mp/bp
- Chemical
- Functional group
- Electrophiles, neutrophiles
- Addition, Sustitution
- Oxidation, reduction
- Acid, base
- Solubility
- Planning synthetic routes
- Now may use computers
- +/- C from organic molecule
- +: RX reflux with KCN dissolved in ethanol
→ nitrile, hydrolysis → RCOOH
- +: Friedel-Crafts alkylation
- -: Hofmann's degradation (amide + Br2
+ KOH + heat → amine)
- -: Hunsdiecker reaction
- Reaction pathways
- Choosing synthesis route
- Starting material, mass
production e.t.c.
- Synthesis of stereo specific drugs
- Enantiomeric drugs
- SN1 → racemic mixture
- Usually only one enantiomer is useful,
the other may be harmful
- Thalidomide
- Separate and test enantiomers
- Making single enantiomers
- Reduced amounts can be given
→ less side effects
- Separate enantiomers
- Thin-layer chromatography
- £££
- Asymmetric synthesis
- Make only one enantiomer
- £££
- Extreme condtions
- Chiral auxillaries
- Direct functional groups
- Keep costs down
- Enzymes
- HSW: thalidomide
- Still used in treatment of leprosy, cancer
- Control measures for hazards
- Fume cupboard, reduce scale, safer route or reactants
- Hazard: the potential to cause harm
- Hazcard
- Risk: the likelihood of harm
- Risk assessment
- Control measures to reduce risk
- Combinatorial chemistry
- Enables automated processes to carry out routine reactions very quickly and accurately
- Used to make structurally similar compounds
- Data libraries → drug development
- Similar drugs, possible uses
- Save time, more compounds synthesised