Basics in Organic Reactions Mechanisms
In organic chemistry, the mechanism of an organic reaction is defined as a complete step-by-step explanation of how a reaction of organic compounds happens. A completely detailed mechanism would relate the first structure of the reactants with the last structure of the products and would represent changes in structure and energy all through the reaction step.
Heterolytic Bond Breaking
Heterolytic bond breaking is also known as heterolysis or heterolytic fission or ionic fission. It is defined as breaking of a covalent bond between two different atoms in which one atom gains both of the shared pair of electrons. The atom that gains both electrons is more electronegative than the other atom in covalent bond. The energy needed for heterolytic fission is called as heterolytic bond dissociation energy.
Polar Aprotic Solvent
Solvents that are chemically polar in nature and are not capable of hydrogen bonding (implying that a hydrogen atom directly linked with an electronegative atom is not found) are referred to as polar aprotic solvents. Some commonly used polar aprotic solvents are acetone, DMF, acetonitrile, DMSO, etc.
Oxygen Nucleophiles
Oxygen being an electron rich species with a lone pair electron, can act as a good nucleophile. Typically, oxygen nucleophiles can be found in these compounds- water, hydroxides and alcohols.
Carbon Nucleophiles
We are aware that carbon belongs to group IV and hence does not possess any lone pair of electrons. Implying that neutral carbon is not a nucleophile then how is carbon going to be nucleophilic? The answer to this is that when a carbon atom is attached to a metal (can be seen in the case of organometallic compounds), the metal atom develops a partial positive charge and carbon develops a partial negative charge, hence making carbon nucleophilic.
A phamacist reconstituted a vial of 750 mg Cefuroxime Sodium Powder for Injection with 6mL of sterile water for injection. The reconstituted solution was dark amber-colored solution. The package insert states that solution colors range from clear to yellow depending on concentration, diluent, and storage conditions. The pharmacist was then hesitant to give the patient the solution due to its unusual dark color.
Five portions were taken from a batch of cefuroxime sodium. Prior to testing in the instrument, each part was subjected to one of the following conditions:
|
Conditions |
Specifications |
|
Temperature |
Portion 1: 8°C ± 2°C Portion 2: 30°C ± 2°C Portion 3: 40°C ± 2°C |
|
Light |
Portion 4: Kept in the dark Portion 5: Exposed to direct sunlight |
a. Which form of the product – the powder for injection, the reconstituted product, or both – will you subject to the following conditions and why?
b. Will you also expose the reference standard of cefuroxime sodium to the same conditions as the sample? Give an explanation for your answer.
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