Describe the use of tollen's reagent to detect the presence of an aldehyde group.

Describe the use of tollen's reagent to detect the presence of an aldehyde group.

Tollen's reagent is a compound that will oxidise an aldehyde to form a silver precipitate (silver mirror), but will not oxidise ketones (since they can not be oxidised any further), hence can be used to distinguish between the two.

Identification Of Aldehyde & Ketone Group

At First We have to Identify Aryl Group : 

 We will use Brayde's Reagent to identify the Aryl Group.

Brayde's Reagent is 2,4-Dinitriphinyle Hydrazin. 

So it is also called 2,4-Dinitriphinyle Hydrazin Test.2,4-Dinitriphinyle Hydrazin itself is a yellow solution.

It will react with aryl group ( both Aldehyde & Ketone ) and will 

give 2,4-Dinitriphinyle Hydrazone precipitate.

2,4 Dinitrophenylhydrazine Test

What Is a Food-Drug Interaction?Any time that a food or beverage changes the effects of a drug, the change is considered a food-drug interaction. Food-drug interactions can occur with prescription drugs, over-the-counter drugs, herbal products, and dietary supplements.

Drug Interaction : 

 Tetracycline should not be taken at the same time as aluminum, magnesium, or calcium-based antacids (for example,aluminum with magnesium hydroxide-oral [Mylanta, Maalox], calcium carbonate [Tums, Rolaids]); iron supplements; bismuth subsalicylate (Pepto-Bismol), and dairy products. These agents bind tetracycline in the intestine and reduce its absorption into the body.

Tetracycline may enhance the activity of the blood thinner, warfarin(Coumadin), and result in excessive "thinning" of the blood, necessitating a reduction in the dose of warfarin. Phenytoin (Dilantin), carbamazepine(Tegretol), and barbiturates (such as phenobarbital) may enhance the elimination of tetracycline and reduce the effectiveness of tetracycline. Tetracycline may reduce the effectiveness of oral contraceptives.

PREGNANCY: Tetracycline antibiotics can impair development of bone in the fetus. Therefore, tetracycline is not recommended during pregnancyunless there is no other appropriate antibiotic.

NURSING MOTHERS: Tetracycline is secreted into breast milk. Since tetracycline can impair the development of bone in infants, nursing mothers should not use tetracycline.

Suppository : 
A medicinal substance designed to melt at body temperature within a body cavity other than the mouth, especially the rectum or vagina. It is a semi-solid dosage form.

Advantages of Suppositories : 
􀂄 Self administration
􀂄 Avoidance of oral and parental routes
– Avoid first pass metabolism
– Protect drug from harsh conditions in stomach
– Drug causes nausea and vomiting
– Oral intake restricted before surgery
􀂄 Patient suffering from sever vomiting
􀂄 Can be targeted delivery system
– Localized action reduced systemic distribution
– Rectum vagina & urethra poor blood flow
􀂄 Get to site of action with lower dose

􀂄 Reducing systemic toxicity

Disadvantages of Suppositories :

􀂄 Mucosal irritation
– Eg: indomethacin can cause rashes
􀂄 Patient compliance
􀂄 Erratic and undesired absorption
– Placement too high -> first pass metabolism
– Installation may trigger defecation reaction
􀂄 expel product
􀂄 GI state affects absorption

– Diarrhea & disease states affect absorption
May get absorption when don't want
– e.g. Estrogen creams
􀂄 ⇑ absorbed into circulation ⇑ Side effects
􀂄 High cost of manufacture
– Special formulation
– Special packaging
􀂄 Lack of comparative data
– Not well researched area
– Company avoid financial risk
􀂄 Can melt at ambient temperatures

– e.g., Baltimore in the summer

                  Differences between Paracetamol & Aspirin : 

Aspirin and Paracetamol both act to reduce pain and lower fever, but are active in different areas of the body and provide different additional benefits. Aspirin will also limit inflammation provides anti-clotting properties, while paracetamol does not offer these benefits. The best drug to take depends on the patient and the situation. Both aspirin and paracetamol are readily available through pharmacies, and patients may want to talk to the doctor about the most suitable drug for their needs.

Paracetamol is a prostaglandin inhibitor and works by limiting the production of cyclooxygenase, a chemical compound the body uses to send pain signals. Aspirin is also a prostaglandin inhibitor, but acts on different compounds like thromboxanes.

Both aspirin and paracetamol will block pain signals and make patients feel more comfortable. Paracetamol acts primarily on receptors for pain in the central nervous system and will block the signal before it reaches the brain. Aspirin acts locally at the site of the pain to stop it from producing pain signals. It will also reduce inflammation if any inflammatory reaction is present. Fever will drop with both medications in patients who have developed a temperature.

Aspirin tends to be harder on the gastrointestinal tract than paracetamol, which can be a cause for concern in patients with stomach problems. Both aspirin and paracetamol can potentially be dangerous for the liver if taken in large amounts. Patients must take care when measuring out doses and timing them to make sure they get enough medication but do not endanger their livers. If a patient does overdose, rapid treatment in a hospital is necessary.

For issues like headaches, paracetamol can be a better choice, as it will block the pain and make the patient feel more comfortable, without gastrointestinal side effects. Aspirin may be the best option when a patient has inflammation as well, as the drug will treat the cause of the pain and block the signals at the same time. Patients weighing aspirin and paracetamol to decide on the best drug should consider whether they need anti-inflammatory properties in their medication.

Patients may take aspirin in the long term as a therapeutic measure to prevent the development of blood clots. Aspirin therapy should be followed under medical supervision only, and it is important to be aware that the drug will not address pain and inflammation, only reduce the susceptibility to clotting. Higher doses will be necessary to treat pain.

How does paracetamol work? ( Pharmacology Of Paracetamol )

Paracetamol is generally considered to be a weak inhibitor of the enzyme cyclooxygenase-2 (COX-2). This enzyme is important in the synthesis of prostaglandins (PG), so by inhibiting the action of COX-2, paracetamol causes a decrease in PG production. Prostaglandins are important mediators of inflammation, and their release has many effects including the sensitization of nerve cells to pain, and a direct effect on the hypothalamus in the brain resulting in fever.

Although paracetamol suppresses inflammation in mice and rats and can reduce swelling after surgery in humans, it is not effective in reducing inflammation in all cases, for example it has no anti-inflammatory effect in rheumatoid arthritis in humans.

Some evidence suggests that the analgesic effect of paracetamol is due to a central effect on the production of serotonin. Serotonin is a neurostransmitter which helps alleviate pain, and short term use of paracetamol has been shown to cause an increase in serotonin levels in the central nervous system.Longer term use of paracetamol is associated with a decrease in serotonin levels, and this is believed to be the cause of analgesic-induced headaches.

                 A Brief History of Organic Chemistry

Organic chemistry is the study of compounds that contain carbon. It is one of the major branches of chemistry.
The history of organic chemistry can be traced back to ancient times when medicine men extracted chemicals from plants and animals to treat members of their tribes. They didn't label their work as "organic chemistry", they simply kept records of the useful properties and uses of things like willow bark which was used as a pain killer. (It is now known that willow bark contains acetylsalicylic acid, the ingredient in aspirin - chewing on the bark extracted the aspirin.) Their knowledge formed the basis of modern pharmacology which has a strong dependence on knowledge of organic chemistry.
Organic chemistry was first defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius. He classified chemical compounds into two main groups: organic if they originated in living or once-living matter and inorganic if they came from "mineral" or non-living matter. Like most chemists of his era, Berzelius believed in Vitalism - the idea that organic compounds could only originate from living organisms through the action of some vital force.
It was a student of Berzelius' who made the discovery that would result in the abandonment of Vitalism as a scientific theory. In 1828, Frederich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound).
Wohler mixed silver cyanate and ammonium chloride to produce solid silver chloride and aqueous ammonium cyanate:

He then separated the mixture by filtration and tried to purify the aqueous ammonium cyanate by evaporating the water
To his surprise, the solid left over after the evaporation of the water was not ammonium cyanate, it was a substance with the properties of urea. Wohler's observation marked the first time an organic compound had been synthesized from an inorganic source.

     

A Turning Point in Science History

Wohler's discovery was a turning point in science history for two reasons. First, it undermined the idea of Vitalism because an organic compound was produced from an inorganic one. However, it also represented the discovery of isomerism - the possibility of two or more different structures (ammonium cyanate crystals and urea crystals) based on the same chemical formula (N₂H₄CO).
Chemists started searching for reasons to explain isomerism. That in turn led to theories about the structure of chemical compounds. By the 1860's, chemists like Kékulé were proposing theories on the relationship between a compound's chemical formula and the physical distribution of its atoms. By the 1900's chemists were trying to determine the nature of chemical bonding by developing models for electron distribution. During all of this time the number of known organic compounds was increasing rapidly year by year.
During the 20^th century, organic chemistry branched into sub-disciplines such as polymer chemistry, pharmacology, bioengineering, petro-chemistry, and numerous others. During that century, millions of new substances were discovered or synthesized. Today over 98% of all known compounds are organic.

 

 

Sources of Organic Compounds

There are three generally accepted sources of organic compounds: 

• carbonized organic matter
• living organisms
• invention/human ingenuity 

Carbonized Organic Matter: Coal, Oil, and Natural Gas

Hundreds of millions of years ago, the organisms that inhabited earth were quite different than those we find here today. Plants were fast growing and lacked the woody tissues associated with the trees that currently dominate the world's productive ecosystems. Giant plants with broccoli-like stems grew rapidly, died, and decayed to form rich organic soils upon which more and more plants grew.
Eventually, thick layers of decomposing organic matter accumulated in much the same way that peat bogs do today. Over time these massive organic layers were buried under sediment, rock, or ice where they were subjected to tremendous pressures. In this way, they were transformed into various types of coal. 
Meanwhile in Earth's prehistoric shallow seas, simple organisms like algae, bacteria and zooplankton thrived. As these tiny organisms died, they formed thick layers of organic matter on the sandy bottoms of these seas. Compression of layer upon layer of this material produced rocks known as shale. Under the tremendous pressures from the layers above, and with the shifting of earths tectonic plates, the organic matter trapped in these rocks was converted to oil and natural gas over millions of years. The oil and gas migrated into porous rocks like sandstones or into large pockets of space located kilometres below the earth's surface. Thus organic matter from the past became today's fossil fuels.
Humans have known about fossil fuels for over 6000 years; however, only during the past 300 years have they been utilized on a large scale. Coal was the first of the fossil fuels to be extracted from the earth on a commercial basis. It was the fuel that drove the steam engines of the industrial revolution in the 18th, 19th, and 20th centuries. 
Through a process called destructive distillation, coal was converted into coke, coal tar, and coal gas. Coke was used in the smelting of ores, coal tar was refined into over 200 different carbon compounds, and coal gas was used for things like street lighting!
Oil emerged as the dominant energy source for transportation in the 20th century. Natural gas is becoming the clean alternative to coal for generating electricity. It is also widely used as home heating and appliance fuel in North America. The economies of the western world are now completely dependent on oil and natural gas.

To some people, the burning of fossil fuels represents a tremendous waste. Not only does this practice contribute to the build up of carbon dioxide in the atmosphere, it also consumes that raw materials needed to make useful substances like plastics. By some estimates, the world will virtually exhaust its supply of oil and natural gas by 2050 - that's within your lifetime!

Nature: Living Organisms

Every living organism is a source of organic compounds. Each species is capable of producing a wide range of compounds, some of which are unique to that single species. The scent of a rose, the taste of a strawberry, and the fuzziness of a peach are the results of biochemical manufacturing processes within living things. Given that there are hundreds of thousands of species on earth, nature represents our most important source of organic compounds.

Humans have extracted and purified thousands of useful compounds from plants and animals. For example, the penicillin used to fight bacterial infections is extracted from a naturally occurring mold. Acetylsalicylic acid, commonly known as aspirin, comes from the bark of a species of willow tree. Vanilla flavouring is extracted from dried beans that come from a species of orchid called Vanilla planifolia. The heart drug digitalis comes from a plant called Digitalis purpurea. The list of examples goes on for volumes of pages.

Invention

Antibiotics, aspirin, vanilla flavouring, and heart drugs are examples of substances that no longer have to be obtained directly from nature. They are manufactured in laboratories from organic starting materials. Furthermore, experiments in which the chemical structures of naturally occurring substances are modified has produced organic compounds substances that do not exist anywhere in nature.
Each year over 250,000 new chemical compounds are discovered and many of these are products of scientists' imaginations, exploration, and in some cases - experiments gone wrong. Plastics are excellent examples of substances that are the product of invention - they are not found anywhere in nature.