Chemistry Option D

Choosing a solvent which selectively dissolves one component of the mixture is called extraction. The solute becomes unequally distributed among the solvents, which is called partition.

• Aqueous mixture containing the solute and two solvents is placed into a separating filter and shaken vigorously.
• The solute dissolves in the solvent which is on either layer.
• This layer is separated by draining.

Fractional distillation

Mole of compound / total mole in mixture

The pressure exerted by a vapour in equilibrium with its liquid form at a given temperature in a closed system. Compounds that are more volatile exert a higher vapour pressure than less volatile compounds at the same temperature.

• Ptotal = Pa + Pb
• Pa = vapour pressure of pure substance x mole fraction of substance

When a solution boils, it produces a vapour which is enriched in the more volatile compounds. When that vapour is condensed, it produces a liquid which is more enriched in the more volatile compound. By repeating the process of boiling and condensation, more separation of the compounds can be achieved.

• GC-MS
• Gas chromatography and mass spectrometry
• Gas chromatography separates the chemical mixture into pure chemicals
• Mass spectroscopy identifies and quantifies the components.

• Mobile phase (gas, helium) this is the solvent
• Stationary phase (microscopic non-volatile liquid coated on the walls)
• Components of a mixture are separated in gas chromatography on the basis of their boiling points and relative solubilities in the gas and liquid phases. More volatile components are eluted more quickly and so have shorter retention times.

• Redox reaction of potassium dichromate used to produce carboxylic acid. The color change indicates amount of ethanol on breath, which is directly proportional to amount of alcohol in blood.
• To enhance this technique, fuel cell intoximeters, where ethanol is oxidized to form ethanoic acid at anode and oxygen is reduced at cathode to produce water. The electric current produced is used to determine amount of ethanol present.
• Presence of CH bond in IR

Each component exerts the same vapour pressure in the mixture, according to its relative concentration, as it does when pure. The intermolecular forces between the particles of the different components are the same as those between the particles in the pure substances.

• It depends on nucleons in various isotopes of the element.
• Stable nuclei have balanced forces between nucleons and are not reactive.
• Unstable nuclei have unbalanced forces between nucleons and an excess of internal energy. The spontaneously decay to form stable nuclei. This is called radioactivity.

Unstable nuclei have unbalanced forces between nucleons and an excess of internal energy. The spontaneously decay by emitting energy and particles to form stable nuclei. This is called radioactivity.

• Natural radionuclides: They have no naturally stable isotope. This includes (U235 and C14)
• Artificial radionuclides: They are induced through rapid bombardment with helium nuclei or neutrons. This is most common in medicinal chemistry.

When particles and antiparticles collide (electron and positron for example), mutual destruction occurs and energy is released in the form of photon (gamma ray). No change occurs in the mass or atomic number of the particle.

A neutron is turned into a proton with the ejection of an electron. Mass number stays the same. Atomic number increases by 1. (0 -1 beta)

Ejection of particles with 2+ charge and 4 atomic mass units. This causes the mass number to decrease by 4 and the atomic number to decrease by 2. (uranium) (4 2 alpha) Alpha particles have very high ionization density, making them useful for TAT.

• Alpha emission
• Ejection of beta particle
• Ejection of gamma ray
• Ejection of positron
• Neutron emission

• Why is radioactivity dangerous?
• It’s ionizing, which means it has the ability to create highly reactive radicals through them removal of electrons. This can cause DNA to break in the presence of H or OH radicals, leading to cancer. Different particles have different ionization densities, making them more or less dangerous. Alpha particles have very high ionization density, making them useful for TAT.

All of them are first order, which means they have a constant half-life.

Ln2 / half life

(0.5)^time/half life x initial moles

A radionuclide or tracer is attached to a chemical (iodine for thyroid or glucose for brain), making a radiopharmaceutical, which is then tracked using gamma cameras. TC99 is the most commonly used tracer.

• Half life is 6 hours, which is enough to complete scan but not too much to hurt the patient.
• Decay involves gamma rays, which are captured by gamma camera.
• Chemically versatile, can bond to a variety of organic molecules.

The positron emitting tracer fluorine 18 is used as a tracer. Positrons are emitted, which then combine with electrons to produce gamma rays.

• Radionuclides that a strong beta particle emitters that also emit gamma rays for imaging are preferred (such as Lu-177 and Y-90). There are two forms:
• External radiotherapy or teletherapy
• Internal Radionuclide therapy

Cobalt-60 is pointed towards site of cancer, releasing beta particles and gamma rays. Linear accelerators or gamma knife radiosurgery is used to increase precision of this procedure

• A radionuclide is injected close to the site of cancer. It emits beta particles and gamma rays.
• Examples include
• Phosphorus 32 for blood disorders
• Strontium 89 for bone cancers
• Iodine 131 for thyroid cancer

Alpha emitting tracer are attached to antibodies, which carry them directly to the cancer cells. This is especially useful in treating widely dispersed cancer (metastasized)

• Very high ionizing energy and thus high probability of killing target cell
• Short range radiation minimizes damage to surrounding cells.

• Fatigue
• Nausea
• Hair loss
• Sterility
• Skin reaction

• Drug preparation
• Administration
• Disposal

Solvents used must be safe to use and cause minimal negative effects to the environment. Waters, alcohol or esters must be preferred instead of chlorinated compounds. Additionally, minimal solvents must be used. Solvents must be recycled rather than burned, which releases GHG into the atmosphere. Leftover solvents cause problems in workers, contaminate soil or water or pose environmental danger bc they’re GHG.

• Most of the waste produced is low level waste (short half lives) such as protective gear. These are stored for hours or days in safe, secure and environmental containers and are disposed of traditionally in landfills or sewers for liquids.
• High level waste is put deep under ground.

Use of fluorescent dyes instead of radioactive isotopes in diagnosis.

• Use in food chain
• Improper disposal
• Widespread use of antibacterial things in homes
• This may lead to superbugs

Fermentation through genetically engineered bacteria

Production of viagra producing ¼ of the waste of usual production

• Reduction of amount of solvent used
• Adoption of shorter synthesis pathways
• Replacement of inorganic catalysts with enzymes
• Recycling of waste

Although enantiomers share the same chemical properties, the react differently in various chiral environments such as different enzymes or receptors in the body. When substances are extracted from cells, on enantiomer exists. Synthetically produced drugs, however, are racemate. Most drugs are racemate (prozac) however, taxol is a single enantiomer drug.

Chemotherapy is the treatment or control of a disease using chemical agents.

It binds to tubulin (main component of microtubules) and halts cell division, thus preventing tumour growth.

Taxol has 11 chiral centres and thus many different enantiomers. Only one is active. Thus, a single enantiomer is produced through the method of asymmetric synthesis aka enantioselective synthesis.

• Chiral auxiliary: a chiral molecule binds to a reactant and physically blocks one reaction site, forcing the reaction to be stereospecific. This requires around 30 steps and has very low yield.
• Semi-synthetic synthesis: 10-DAB is extracted from the leaves of yew trees and undergoes chemical change to produce taxol.
• Plant cell fermentation: taxol is directly harvested from plant cells, elimindating the use of harmful solvents.

It is an optically active substance that is temporarily bound to an organic molecule, physically blocking on reaction site and forcing the synthesis to be asymmetric, resulting in a single enantiomer.

The rotation of the plane polarized light indicates the presence of an enantiomer.

• They have no specific components which can be targeted like bacteria.
• They multiply very quickly, and thus have high mutation rates.

• They may alter the cell’s DNA
• They may block enzyme activity in the cell to prevent the virus from reproducing.
• They may cause changes in the cell membrane of the host cell, preventing the virus from entering the cell.
• It is, however, better to use prophylactic treatments such as vaccines to prevent the sickness before it occurs.

They prevent the virus from exiting the host cell by inhibiting the enzyme neuraminidase. Thus, they must be taken shortly after the symptoms are observed. Otherwise, too many viruses will have already been released.

• Tamiflu
• Oral injection
• Antiviral
• Neuraminidase inhibitor
• Resistance of rare strains observed.

• Relenza
• Inhaled
• No resistance
• Neuraminidase inhibitor

• Viruses that have RNA instead of DNA such as HIV.
• Why is HIV hard to treat?
• Virus lies dormant in host cells so there’s nothing to treat
• Virus directly targets white blood cells
• Virus mutates rapidly, forcing the body to react differently in short periods of time.

• It is treated through the use of antiretroviral drugs.
• The drugs work by:
• Preventing the virus from binding to receptors on the cell membrane
• Preventing the reverse transcription of RNA into DNA in the host cell
• Preventing new virus to exit the cell membrane

• Sociocultural taboos
• Costs, distribution and availability
• Patient compliance and regimen

• Combination or specific ARVs
• Cheaper and quicker determination of HIV positivity
• Reduction in taboo

Cells in the inner lining of the stomach wall which release stomach acid (HCl)

Alcohol, smoking, caffeine, stress

• Acid indigestion (feeling of discomfort)
• Heartburn (acid reflux)
• Ulceration (damage to inner lining of gut wall, leading to inflammation and loss of tissue)
• These are all called dyspepsia.

• Antibiotics against the bacteri helicobacter, which may cause ulcers
• H2 receptor antagonists (Ranitidine, Zantac) (which limit histamine- H2 receptor interaction and thus prevent the release of acid from parietal cells)
• Proton pump inhibitors (omeprazole, prilosec, esomeprazole, nexiom) (which limit ATPase, which produces energy for the function of proton pumps)
• Antacids (weak basic compounds such as metal oxides, hydroxides, carbonates or hydrogencarbonates, which neutralize HCl)

H2 receptor antagonists (Ranitidine, Zantac) (which limit histamine- H2 receptor interaction and thus prevent the release of acid from parietal cells)

• They neutralize HCl and produce salt. Mg used for faster relief. Al for longer relief. Al may cause Alzeihmer’s.
• Antacids containing carbon groups may cause bloating, so they usually also have antifoaming components. You may also alginates which float on top of the mixture to prevent reflux.

• [H or OH] = Ka x [acid or base] / [salt]
• Or pH = pKa + log([acid] / [salt])
• To calculate pH when something is added, just add the H concentration or sth to the acid concentration)
• When water is added, there’s no change in pH.

Because as long as the mixture has equal amounts of acid/ base and salt, we just have to choose an acid/ base with a pKa or pKb to the intended pH and it’s super easy.

• Salt dissociates fully
• Dissociation of weak acid/ base is negligible or = 0

They are corrosive (too strong).

These drugs prevent pain by eventing the transmission of pain at the brain rather than at the site of injury. Opiates (drugs produced from the opium poppy) are examples of stron analgesics?

The drugs bind to opioid receptors in the brain, preventing the transmission of signals. Because they affect the brain, they’re narcotics. Although they’re the most effective way to manage pain, they have a large capacity to cause dependence or addiction and have heavy side effects, which means they must be used under heavy medical supervision.

The drugs must pass through the blood-brain barrier, which is a membrane made from lipids. Thus, low polarity and high solubility in lipids ensure higher effect.

• Usually prepared from morphine, least effective, second stage of pain management, found in cough medication and used to treat diarrhea.
• It’s a semisynthetic drug
• Although it is less polar than morphine and thus more likely to cross the blood-brain barrier, the reaction of replacing one OH group with an ether group causes a significant drop in its binding with opioid receptors, rendering it a weaker analgesic.

Can be obtained directly from opium. Used in the management of severe pain. May cause dependency.

• Usually obtained from morphine, highly effective, only used in select countries, initially produces euphoric effects, high risk of addiction and abuse.
• It’s a pro-drug, as the ester functional groups are broken down by esterases in the brain and most of the drug’s functionality comes from the metabolic product that is morphine. It can be thought that diamorphine is sort of like a package that delivers the morphine to the brain in a faster and more efficient manner.

• Weak analgesic
• Weak opioid such as codeine
• Strong opioid such as morphine

• Constipation
• Suppression of cough reflex
• Constriction of the pupil in the eye
• Narcotic effects (depression of brain function, causing sleep and addiction)
• Methadone may be used as an alternative to opioids in the treatment of opioid dependency / addiction.

Chemicals that stimulate pain receptors located on the body. This sends nerve signals to the brain for the sensation of pain, fever (temperature regulation), and inflammatory response (widening of veins)

Drugs that inhibit the release of prostaglandins and the site of pain/ injury (not the brain), such as aspirin. Because they don’t interfere with the functioning of the brain, they’re also called non-narcotics.

• Salicylic acid undergoes esterification in the presence of ethanoic anhydride, producing aspirin and ethanoic acid
• Concentrated sulfuric acid or phosphoric acid is is added and the mixture is gently warmed.
• The mixture is left to cool and is then washed with water. As aspirin has very low solubility, the acids are washed away as aspirin is isolated.
• The mixture is purified through recrystallization. The mixture is dissolved in ethanol, as the impurities are more soluble in it than aspirin. Aspirin is then removed through filtration as the impurities and unreacted salicylic acid remain in the solution.

• Melting point determination
• Or infrared spectroscopy. The dip indicating OH group in phenol will only be present in salicylic acid. Ester group will only be present in aspirin.

Mass of salicylic acid used to mass of aspirin produced

Drugs taken to prevent diseases (such as aspirin taken to prevent heart disease or rectal cancer)

• May cause stomach ulcers
• May have synergy with alcohol and cause ulcers
• May cause Rye’s in children
• May be dangerous for people whose blood does not clot normally, as it is an anticoagulant

If it isn’t soluble enough, it can be turned into an ionic salt through the reaction with NaOH or NaHCO-, increasing its solubility and polarity. However, this can only be done with a drug that contains an acidic or basic functional group (such as OH)

• 4 membered ring containing a cyclic amide group (N and 3 carbon atoms) is the part of the molecule responsible for antibacterial properties.
• The bonds are weak and break easily, resulting in the biological activity of the compound.
• These rings are found in penicillin.

The beta-lactam ring inhibits the enzyme transpeptidase, responsible for the building of cell walls. The beta lactam ring breaks and bonds to the active site of the enzyme. These antibiotics are only effective against bacteria and not plant or animal cell walls, as a different amino acid is used in the formation of bacterial cell walls.

• Many people are allergic to it.
• Penicillin G must be injected into blood.
• Improper use may cause superbugs and antibacterial resistance. (Resistant bacteria produce penicillinase, rendering it ineffective.)

• Not completing the treatment
• Overuse and overprescription
• Use of the antibiotics in the food chain

• By producing different antibiotics such as methicillin. (Modification of R group deems it resistant to penicillinase)
• Limiting the use of antibiotics through legislation (making them prespcription only drugs)
• Education of patients

The sum of all biochemical reactions occurring in the body of an organism.

A drug is a chemical that affects the functions of the body either in a negative or positive way.

Substance that has a therapeutic effect on the body, also known as a beneficial effect.

• Suppositories: inserted into the rectum for digestive illnesses or hemorrhoids
• Parenterals: Intramuscular (vaccine), intravenous (anaesthetics), subcutaneous (dental injections)

How much of a drug is administered at a certain frequency. Many factors such as age, sex, severity of condition, possible side effects affect dosage. Although it is impossible to keep the level of the drug in blood at a specific level and fluctuations are unavoidable, drug level in the blood must be kept within the therapeutic window, which is the range between the toxic level and the therapeutic level.

The fraction of the administered dosage that reaches the bloodstream.

• The administration of the drug: first-pass effect (the alteration of drugs due to enzymes present in the digestive system) may be effective. Intravenous administration has a higher bioavailability by rule of thumb.
• The solubility of the drug: Water solubility is important for blood circulation. Lipid solubility is important for crossing membranes.
• Functional groups in the drug: The functional groups affect the acid-base properties of the drug, thus affecting its solubility and reactivity in different parts of the body.

Physiological effects that are not intended. May either be beneficial (aspirin protecting against heart disease) or benign (drowsiness etc.)

Occurs when repeated dosages result in smaller results.

Occurs when patient becomes dependent on drug to normally carry out life and experiences withdrawal symptoms.

• Ratio of the dose that causes a medically adverse effect on the population and the dose that causes a therapeutic effect on the population.
• Defined as LD50/ED50 in animal studies and TD50/ED50 in human studies.
• Higher the therapeutic index, the larger the therapeutic window and safer the drug. Drugs with low therapeutic index are typically those whose therapeutic effects are highly affected by bioavailability.

It is the minimum effective dose. The minimum dose that creates a beneficial effect on 50% of the population.

Is the dose that is lethal to 50% of the population. This is only used in animal trials for ethical reasons.

It is the dose that is toxic to 50% of the population. This is only used in human trials.

The action of a drug depends on drug-receptor interactions. The receptors can be DNA, enzymes (proteins) or chemical structures on the cell membrane. The bonds are usually non-covalent interactions such as ionic bonding, Van der Waals forces, hydrogen bonding etc. The better the fit between the receptor and the drug, the higher the activity of the drug.

Rational drug design identifies a target molecule and designs a drug to interact with the target receptor. A lead compound (such as a plant extract etc.) is identified. Analogues to that drug are designed and produced. The drug is first tested on 50-100 healthy volunteers, then 200-400 patients and 3000 patients with placebo. After the drug is marketed, most countries continue monitoring.

Hydroxyl

Alkenyl

Ketone

Arene

Carboxylic acid

Ether

Primary amino

Secondary amino

Tertiary amino

Carboxyamide

Ester

• Heterocyclic (no circle) with N or sth instead of C functional group
• Heterecyclic ring