Experimental determination of structure Flashcards
Empirical formula definition
The simplest ratio of elements in the compound.
Empirical formula mass of elements present
Divide mass of elements by RAM
Divide by the lowest number
Find ratio and the empirical formula.
Empirical formula percentage by mass
Divide percentage by elements RAM
divide by lowest number
Find ratio and empirical formula.
Empirical formula combustion products
Divide compounds by RAM
multiply by elements RAM
Divide by lowest number
Find empirical formula and ratio
What can empirical formula be found from
Percentage by mass
Mass of elements present
Masses of combustion products
Mass spectrometry uses
To find the accurate molar mass and structural features of a product
Mass spectrometry procedure
A sample of the compound is bombarded with electrons
Removing electrons from the sample and producing a positively charged molecule.
The molecule breaks into smaller ion fragments.
A mass spectrum is them plotted using mass charge ratio and percentage abundance.
Parent ion
The largest positively charged ion in a mass spectrometry
Mass spectrometry definition
Where electrons bombard a sample to produce positively charged ions, allowing the mass to charge ratio and abundance to be determined.
Infrared spectroscopy procedure
Infrared radiation will be passed through a sample.
A detector will measure the infrared radiation which is transmitted through the sample and determine the absorbance of the sample.
Units for wave numbers
cm-1
Wave numbers formula
1/ wavelength
Where are wave-numbers found
P15 of the data booklet
How does infrared spectroscopy work
Infrared radiation is directed at the sample
The infrared radiation will be absorbed causing the bonds within the molecule to bend and vibrate.
Meaning different wavelengths of infrared radiation are absorbed by different functional groups.
Rule of infrared spectroscopy
Different wavelengths of light are absorbed by different functional groups.
NMR procedure
Radio frequency waves are directed at a sample of a compound.
This causes the nuclei of the atoms to align with the field or against the field.
When radio frequency waves are absorbed the nuclei aligned with field (low energy) will flip to the high energy alignment.
When the high energy alignment nuclei relax back to the low energy alignment radio frequency is emitted producing a spectrum of lines.
This is the chemical shift of the spectrum.
Chemical shift (NMR)
The spectrum of lines produced by the high energy alignment of the nuclei emitting radio waves.
What is chemical shift affected by
the type hydrogen environments.
What is the standard relative substance in NMR
tetramethylsilane
(Silicon with methyl groups around it).
Chemical shift units
ppm - parts per million
Not the same as x10-6
Information on high resolution NMR
chemical shift of environments
Number of hydrogen environments
Number of hydrogen atoms in each environment
Number of hydrogen atoms on adjacent carbon atoms.
Information on low resolution NMR
Number of hydrogen environments
Number of hydrogen atoms in each environment
chemical shift of environment
Number of different hydrogen environments
The number of different hydrogens in different positions on the molecule
How do you find the ratio of hydrogen atoms in each environment
The area under the curve is the ratio of hydrogen atoms in each environment.
Rule for hydrogen atoms on adjacent carbons
N+1 rule
Singlet
0 adjacent hydrogens
Doublet
1 adjacent hydrogens
Triplet
2 adjacent hydrogens
Quartet
3 adjacent hydrogens
Drugs definition
Substances which alter biochemical processes in the body.
How do drugs work
They bind to specific proteins
Proteins that drugs bind to
Receptors and enzymes
Agonists
Drugs which bind to receptors and mimic the action of the body’s natural active compounds.
Antagonist
Drugs which bind to the receptors and block the action of the body’s natural active compounds.
Inhibitors
Drugs which bind to the enzymes active site and prevent a substrate from binding to the active site, preventing the reaction normally catalysed.
How do drugs bind to receptors
Van der waals and ionic bonding
NMR low resolution production
- X axis is chemical shift and Y axis is intensity.
- The number of lines is the number of hydrogen environments.
The intensity shows the ration of hydrogens in the different hydrogen environments
