Chemistry Topic D9:
side effects of abusing anabolic steroids
Abusing anabolic steroids can have a major impact on the body - their use can cause a number of side effects such as breast growth in men, acne, infertility, mood swings and aggressiveness. They can also cause high blood pressure, liver disease (including cancer), heart attacks or strokes. Psychologically, abusers of anabolic steroids can become addicted to them, developing an increased desire to keep taking them, even if unwanted side effects occur.
fuel cell
An electrical-chemical device that converts fuel, such as hydrogen, into an electrical current. Device that combines hydrogen, or other fuels, and oxygen and produces electricity in the process.
mixture of liquids and boiling point relationship
Because the vapor pressure of a mixture of two liquids varies with the composition, the boiling point also varies with the composition of the mixture. The richer a mixture is in the more volatile component, the lower the boiling point.
androgen
Male sex hormone
by using which three techniques can the structure of many organic molecules can be determined?
a combination of infrared spectroscopy, mass spectrometry and proton NMR.
ideal solution
a mixture of liquids in which the intermolecular forces are the same as in the pure liquids - i.e. the tendency for a liquid to evaporate is the same in the pure liquid as in the solution. An example of a fairly-close-to-ideal solution is a mixture of hexane (C6H14) and heptane (C7H16).
what equipment is used to remove the organic solvent? include some benefits and details
a rotary evaporator this device takes the solvent off under reduced pressure-this means that the solution does not have to be heated so much which is important if the product is thermally unstable.
what process is used if the drug does not precipitate out of the reaction mixture?
a separating funnel is used in a process called solvent extraction This involves shaking the aqueous mixture with a solvent that is immiscible with water in a separating funnel and allowing the polar molecules to dissolve in the aqueous layer and the drug (which is organic and most likely lipophilic) to dissolve in the organic layer the layers are then separated
after extraction, what is the next process a drug must undergo?
purification
most common types of purification?
recrystallisation, distillation/fractional distillation and chromatography.
what does Raoult's Law state about vapor pressure?
that the partial vapor pressure of any volatile component of an ideal solution is equal to the vapor pressure of the pure liquid multiplied by the mole fraction of that liquid in the solution. it basically says that the contribution of each component of a mixture to the total vapor pressure depends on what the vapor pressure of the pure liquid is and how much is present in the mixture.
boiling point in terms of vapor pressure
A liquid boils when its vapor pressure equals the external pressure. So the normal boiling point of a liquid is the temperature at which the vapor pressure of the liquid is one atmosphere.
boiling point composition diagram
Consider a mixture in which the mole fraction of A is 0.3 (and that of B is 0.7) - the green dashed line (in Figure D.47) is drawn up from this composition to the liquid line and it can be seen that the boiling point of this mixture is 81 °C. The horizontal line across to the vapor curve (black dashed line) indicates the composition of the vapor with which this liquid is in equilibrium. It can be seen that the mole fraction of A in the vapor is 0.6, compared to 0.3 in the liquid - the vapor is richer in the more volatile component.
what happens to boiling point when a non-volatile substance is dissolved in a solvent?
Dissolving a non-volatile solute in a solvent will increase the boiling point of the solvent (boiling point 'elevation') because the vapor pressure is lowered and therefore the liquid must be heated more so that its vapor pressure is equal to atmospheric pressure
vapor pressure with pure liquids vs mixture of liquids
For a pure liquid, the vapor pressure depends only on the nature of the liquid and the temperature. For a mixture of liquids, the vapor pressure also depends on how much of each liquid is present.
how fractional distillation works with diagram
If a mixture containing 0.1 mol A and 0.9 mol B is heated in the ask, it will boil at 87 °C (Figure D.48). The mole fractions in the vapour will be XA = 0.3 and XB = 0.7 - so the vapour is richer in the more volatile component. The fractionating column is hot at the bottom and cooler at the top so, as the vapour rises up the column to the cooler parts, it condenses on the beads in the column to form a liquid with composition XA = 0.3 and XB = 0.7. This liquid will then trickle down the column, where it is heated by hotter vapour coming up from below and will boil again, but this time at a lower temperature (81 °C) because it is richer in the more volatile component. This liquid will boil to form a vapour with composition XA = 0.6 and XB = 0.4. This vapour is richer in the more volatile component and rises higher up the column before it condenses to form a liquid of the same composition. The liquid trickles down the column where it is heated again and boils at 74 °C to form a vapour of composition XA = 0.84 and XB = 0.16. Each time the liquid boils and condenses it becomes richer in the more volatile component and rises higher up the column until, if the column is long enough, essentially pure A will be obtained from the top of the column.
what essential characteristic about alcohol levels in the breath allow breathalyzers to work?
In the lungs, an equilibrium is established between alcohol dissolved in blood plasma and alcohol in the breath. Therefore, the amount of alcohol in the breath can be used to determine the amount of alcohol in the blood plasma.
more accurate alcohol tests use fuel cells to measure alcohol in the breath using fuel cells how do they work?
In this type of device, the breath enters a fuel cell fitted with two platinum electrodes and any alcohol in the breath gets oxidized. Instead of the energy being released as heat, it is converted directly to electrical energy and an electric current is generated - the more alcohol present, the higher the current.
the presence of which groups in a molecule increase its water solubility?
OH groups and NH/NH2 groups
substances containing which forms of atoms are more water soluble and why?
Substances containing ions tend to be more soluble in water because of the formation of ion-dipole interactions.
closeness of boiling points and the number of boiling/condensing processes plus caveat of fractional distillation
The closer the boiling points of the liquids, the more series of boiling and condensing processes are required and therefore the longer the column required for good separation of the liquids. Not all liquids can be completely separated by fractional distillation and, for instance, ethanol and water form a constant-boiling-point mixture (95.6% ethanol).
process of breathalyzer
The first uses a chemical test in a breathalyzer, which either contains dichromate(VI) (Cr2O7 2−) ions in crystals or solution. Dichromate(VI) ions are orange and any ethanol present in the motorist's breath will cause a change in colour to green as they are reduced to chromium(III) ions - the ethanol is first oxidized to ethanal and then to ethanoic acid in the process. The degree of colour change is directly related to the level of alcohol in the breath. In the simple, disposable devices using potassium dichromate(VI) crystals, the amount of alcohol in the breath is determined by how many crystals change colour. In devices using potassium dichromate(VI) solution the amount of colour change can be measured using a colorimeter/photocell.
how are volatility and boiling point connected?
The more volatile a liquid is, the higher its vapor pressure will be at a certain temperature - and therefore the lower its boiling point will be.
simplified method for determining steroid use
The organic chemicals are extracted from a urine sample and then separated into their various components using gas chromatography (gas-liquid chromatography). Each band, as it comes out of the chromatography column, is passed directly into a mass spectrometer where it is analyzed. The mass spectrum of a compound is generally characteristic of that compound and so, by comparison with the mass spectra in a database, the compound can be identified.
mole fraction of a component
The sum of the mole fractions of the various components in a mixture is 1.
basic process of fractional distillation and its purpose
This can be used to separate liquids that have quite similar boiling points - whereas simple distillation is used to separate liquids with very different boiling points or for separating a liquid from a non-volatile residue. The column is made of molded glass or is packed with small beads to give a very large surface area. The mixture of liquids is heated and the liquid with the lower boiling point is collected by condensing the vapor
first way to extract drugs from the mixture
adding the reaction mixture to ice-water. If the product is a solid and insoluble in water it might precipitate at this stage and can be removed from the reaction mixture by filtration.
retention time
amount of time a compound spends in stationary phase
testosterone is an example of an
androgen
why is aspirin more soluble in alkaline solutions rather than acidic solutions?
aspirin is less soluble in acidic solutions than in alkaline solutions because of the formation of ions in alkaline solution - the conversion of aspirin to its sodium salt to increase its solubility
even though ethyl ethanoate is polar, why is it less water soluble than methyl methanoate?
because it has more non-polar regions (CH3 groups)
vapor pressure and intermolecular forces and boiling point
boiling point depends on the volatility of a liquid and volatility is directly related to the strength of intermolecular forces hydrocarbons only have london forces due to their non-polar nature while water has hydrogen bonds this is why oils will boil at a lower temperature because their vapor pressure is higher at lower temperatures because they are more volatile and therefore evaporate more easily creating more vapor with a lower temperature
what techniques are used to test for anabolic steroids
combined techniques of gas chromatography-mass spectrometry
The structures of ethanoic acid and methyl methanoate, which are isomers of each other which is more water soluble and why?
ethanoic acid is because it has hydrogen bonding while methyl methanoate does not even though they are isomers
vapor pressure
is the pressure exerted by a vapor in equilibrium with a liquid (or a solid).
what must happen once the drug is made in the reaction mixture?
it must be extracted from the reaction mixture
which are more water soluble and why?
left to right due to more OH groups
what is the general rule for solubility of molecules?
like dissolves like polar molecules will dissolve in polar substances non-polar molecules will dissolve in non-polar, organic solvents
partial pressure
refers to the pressure exerted by a particular gas in a mixture of gases. If the gases behave ideally, the partial pressure is the same as the pressure that the same amount of that particular gas would exert if it were in the container by itself. If the pressure exerted by a mixture of 80% nitrogen and 20% oxygen is 100 kPa, the partial pressure of nitrogen is 80 kPa and that of oxygen is 20 kPa. Partial pressure is calculated from: partial pressure of A = mole fraction of A × total pressure
which structure (RNH) is present in many drugs?
secondary carboxamide (amide) group
volatile
something that evaporates readily
what is the common structural feature in steroids called?
steroid backbone Steroids vary depending on the type and position of substituents on this steroid backbone. There is also usually a carbon-carbon double bond in either ring A or ring
the three most commonly abused anabolic steroids
testosterone and the synthetic derivatives nandrolone and stanozolol
what ability of a molecule often makes it more soluble in water?
the ability to form hydrogen bonds
what is gas chromatography used for?
the separation of mixtures, such as drugs in urine.
anabolic steroids
they promote tissue growth, of muscle in particular.
how can alcohol be detected in the breath?
using redox reactions - either using an oxidizing agent in a chemical reaction or in a fuel cell.
what is the first step in identifying a compound?
usually to run an infrared spectrum
structures of zanamivir vs omeprazole which is more water soluble?
zanamivir due to more OH groups
detailed process of using a gas chromatograph with illustration
• An inert gas (usually nitrogen or helium), called the carrier gas, carries the sample through the column. • The column contains a non-volatile liquid (the stationary phase) spread onto the surface of evenly divided solid particles. As the mixture is carried through the column, it separates into its components. Separation is by partition - so how quickly each component travels depends on its solubility in the liquid stationary phase. Those with higher solubility in the liquid stationary phase are slowed down in the column relative to those that are less soluble in the stationary phase. The retention time, the time between when the mixture is injected and the time it is detected, also depends (among other things) on how volatile the substance is - the most volatile compound generally has the greatest tendency to enter the gaseous phase and therefore the shortest retention time. • Each component is fed into a mass spectrometer as it emerges from the column.