Experimental determination of structure, pharmaceutical chemistry Flashcards
What can elemental microanalysis (/combustion analysis) be used to determine
Empirical formula of an organic compound
Describe the process of elemental microanalysis
A tiny sample is accurately weighed and oxidised at a high temperature in an oxygen rich atmosphere
The product mixture of CO2, H2O, N2, SO2 is separated using gas chromatography and the mass of each component is measured using a thermal conductivity detector
What is mass spectrometry used for
A technique to determine the accurate molecular mass and structural features of a compound
What happens to the sample being analysed in a mass spectrometer
It is vaporised and and bombarded with high energy electrons which knocks electrons off the molecule and as a result the molecules break into positively charged ion fragments
What happens to the positively charged ion fragments in a mass spectrometer
They’re accelerated by a high voltage electric field into a strong magnetic field that deflects them into a series of separate ion paths according to their mass/charge ratio.
What is the difference between positive ion fragments with a lower or higher mass/charge ratio
Ions with lower mass/charge ratios are deflected more than those with higher ratios
What are the common types of bond vibration
Stretching and bending
What affect does infrared radiation have on bonds
Causes them to vibrate but not break
What determines the wavelenght of infrared radiation that a bond absorbs
The type of atoms and the stiffness (strength) of the bond
In general, which bonds absorb infrared radiation with a shorter wavelength
Light atoms with stiff bonds
What does infrared spectroscopy make use of
Identifies the atoms and bond strength of a bond to identify specific bonds and functional groups
Describe the process of infrared spectroscopy
Infrared radiation is passed through the sample in a spectrometer, Some wavelengths are absorbed causing bonds to vibrate.
The transmitted radiation passes to a detector where the intensity of different wavelengths is measured.
Explain why protons behave like tiny magnets when placed between the poles of a powerful magnet
Some atomic nuclei spin about their own axes
Whats the energy of protons aligned with the magnetic field compared to those aligned against it
Protons aligned with the field have lower energy
What corresponds to the radio frequency region of the electromagnetic spectrum with reference to proton nuclear magnetic resonances spectroscopy
The energy difference between protons aligned with and against the magnetic field
What happens when protons are exposed to radio waves
Energy is absorbed to promote those in lower energy state to the higher energy state
The protons flip from being aligned with the magnetic field to being aligned against it
What is proton nuclear magnetic resonance
When protons fall back to a lower energy state and emit energy with the same frequency as what they absorbed (radio waves) - can be measured with a radio reciever
What does proton nuclear magnetic resonance spectroscopy tell us
How many different chemical environments the protons in an organic molecule molecule can exist
How many protons are in each of these environments
The type of proton environment
Wha is the common standard in 1H NMR spectroscopy
TMS - Tetramethylsilane
What does 1H NMR stand for
Proton nuclear magnetic resonance
Define chemical shift
The difference between protons in TMS and the protons in other chemical environments
What is chemical shift measured in
Parts per million (ppm)
Whats the difference in high resolution 1H NMR spectroscopy and regular 1H NMR spectroscopy
High resolution 1H NMR spectroscopy uses radio waves of a higher frequency which results in a more detailed spectra being produced
What are the multiple peaks of a high resolution 1HMR spectroscopy graph called
Multiplets
What does it mean if there is more than one peak in a proton environment and how are they caused
There must be hydrogen atoms within that environment experiencing slightly different magnetic fields
Caused by the influence of the hydrogen atom on the neighbouring carbon atom (as hydrogens have a magnetic field of their own)
What does the additional detail of a high resolution 1HMR spectrum provide us with
Allows the neighbouring proton environment to be identified
What is the n + 1 rule
A way of identifying the neighbouring proton environment where n is the number of hydrogen atoms atoms attached to the next door carbon atom and n + 1 is the number of peaks in the cluster
What is a drug
A substance that can have biochemical processes in the body
What is a medecine
A drug which has a beneficial effect
What may be added to some medecines
A filter if the active ingredient is very small
A sweetner
A coat - to be swallowed
List some examples of ancient medecines
The bark of willow - lessens pain, fever, inflammation
Opium as painkiller/sedative
Cinchona bark for malaria
What is an agonist
A substance that will produce a response similar to the bodies natural active compound
What is an antagonist
A substance that produces no response but prevents the action of the body’s natural active compound
How do drugs work
By binding to receptors
What is a receptor
Receptors are protein molecules on the surface of cells where they interact with biologically active molecules, or are enzymes that catalyse chemical reactions
What is critical about the shape of a drug
It has to fit its binding site
How do drugs usually work
Many drugs act as enzyme inhibitors by binding to the
enzyme’s active site and blocking the reaction normally
catalysed there
What are the main types of bonding between a drug and its receptors binding site
Van der waal’s and ionic usually
What can a sulfonamide be if active
An antibacterial agent
