Chapter 9, 10 and 11: Medicinal Chem Flashcards
Carbon - carbon double bonds
- bromine water test ( qualitatative)
- if the water goes clear there are double bond - iodine number (quantitative)
- 1mol of I2 reacts with 1mol of c=c double bonds
- how much iodine has reacted with 100g of a substance
Testing for hydroxyl groups
- Oxidation (permangenate or dichromate)
- k dichromate = alcohol is added to the dichromate, if it turns green it is a primary of secondary alcohol if it turns orange is it a tertiary alcohol - Esterification
- adding a carboxylic acid to the suposed alcohol, if there is a sweet smell then the unknown is an alcohol - Sodium metal
- Add sodium metal, if H2 gas is produced then a hydroxly group is present, carboxylic acids will also react
they are all qualitative analysis
Testing for a carboxly functional group
- Hydrogen carbonate
- carboxylic acids will react with hydrogen carbonates to produce CO2 gas, which is observed as bubbling, limewater will turn cloudy for further testing. - Esterification
- A carboxlic acid will create a sweet smell when mixed with an alcohol. - pH
- an acid base indicator like phenolphthalein, can detect a change in pH, partially ionising in water producing H+ ions, if a weak acid is preset, then its likey to be a carboxlyic acid.
they are all qualitative analysis
Analysis of mixtures
is not the functional group testing as they are pure not a mixture.
Melting point
melting point determination
- the identification of a compound by comparison of an experimental melting point value to a literature value, and the purity of a sample to be measured.
- Impure samples have a wider and lower melting point range than pure samples of the same substance
- To confirm the identify of an unknown compound, the experimental sample can be mixed with a known substance in a 1:1 ratio
Boiling point
Distillation
1. Simple
- Simple distillation involves heating a mixture to a target temperature to vaporise the components to be separated. Vapour fractions are condensed and collected.
2. Fractional
- i know this one, temperature gradient, making them pure
Spectroscopy
- Infrared
- NMR
Infrared Spectroscopy (IR)
- vibration of covalent bonds by IR radiation.
- the upside down graphs, the O-H looks big and wide
- allows identification of the functional groups and single, double and triple bonds in organic molecules
- identifies the specific energy absorbed by the various covalent bonds
- below 1500 is the fingerprint region, containing a pattern of peaks individual for an individual molecule.
qualitative analysis
NMR Spectroscopy
- NMR is a qualitative analysis method used to determine molecular structure
- NMR utilises a property of certain nuclei called ‘spin’ to identify the location of atoms within a molecule. Nuclei with an odd number of nucleons can be detected by NMR, as they have two overall spin states (e.g. 1H and 13C).
- Radio waves are provided to change the spin state of the nuclei, which can then be detected.
- Electrons surrounding a nucleus will somewhat shield it from the applied magnetic field of an NMR spectrometer. As such, the radio wave energy required to change the spin state of nuclei differs depending on the extent of shielding.
- tetramethylsilane (TMS). The value for the TMS signal is set to zero
- n + 1 rule
Spectrometry
- only mass spectrometry
Mass Spectrometry
FRAGMENTATION = [CH3]+
- Base peak is the tallest one
- Parent peak is the M of the molecular ion
- m/z thing
- The isotope effect can explain the presence of multiple peaks for fragments with the same formula due to the presence of isotopes of the constituent elements.
- Fragment destoryed in the process
m/z
the ratio of the mass of an ion relative to its charge
Relative abundance
the abundance/intensity of an ion relative to the base peak
- mass spec
Chromatography
- Chromatography is a technique used to separate components of a mixture. Once separated, the components can be identified (qualitative analysis) and their concentration in the sample determined (quantitative analysis).
- Mobile phase and stationary phase, opposite polar or non-polar
- Components are detected as they exit the column and recorded as a series of peaks on a chart called a chromatogram, including both the retention time, Rt, and area of each peak.
- Retention time can be used to identify a component, by comparing the retention time for an unknown substance with those for known substances under the same operating conditions.
- can use results to make a calibration curve
Stereoisomers
the atoms are connected in the same order but are oriented differently in space. As a result, stereoisomers tend to have different chemical properties.
- same atom to atom bond but oriented differently in space