Chemistry lecture 19

Organic Chemistry

Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds. Organic compounds are composed of carbon and hydrogen, and can possibly contain any of the other elements such as nitrogen, oxygen, phosphorus, and sulfur.

History:         Organic chemistry as a science is generally agreed to have started in 1828 with Friedrich Woehler's synthesis of the organic, biologically significant compound urea by accidentally evaporating an aqueous solution of ammonium cyanate NH₄OCN.

Why Is Organic Chemistry Important?

Organic chemistry is important because it is the study of life and all of the chemical reactions related to life. Several careers apply an understanding of organic chemistry, such as doctors, veterinarians, dentists, pharmacologists, chemical engineers, and chemists. Organic chemistry plays a part in the development of common household chemicals, foods, plastics, drugs, fuels... really most of the chemicals part of daily life.

Organic chemists usually conduct research and development in a laboratory setting. Projects that would use organic chemists would include development of a better painkilling drug, formulating a shampoo that would result in silkier hair, making a stain resistant carpet, or finding a non-toxic insect repellent.

Characteristics of organic substances

The reason that there are so many carbon compounds is that carbon has the ability to form many carbon chains of different lengths, and rings of different sizes (catenation). Many carbon compounds are extremely sensitive to heat, and generally decompose below 300°C. They tend to be less soluble in water compared to many inorganic salts. In contrast to such salts, they tend to be much more soluble in organic solvents such as ether or alcohol. Organic compounds are covalently bonded.

Organic nomenclature is the system established for naming and grouping organic compounds.

Aliphatic compounds are organic molecules that do not contain aromatic systems. ....

Aromatic compounds are organic molecules that contain one or more aromatic ring system.

Heterocyclic compounds are cyclic organic molecules whose ring(s) contain at least one heteroatom. These heteroaoms can include oxygen, nitrogen, phosphorous, and sulfur.

Polymers

Polymers are a special kind of molecule. Generally considered "large" molecules, polymers get their reputation regarding size because they are molecules that consist of multiple smaller segments. Polymers can be organic or inorganic. Commonly-encountered polymers are usually organic.But inorganic polymers (e.g., silicone) are also familiar to everyday items.

Currently, there exist several methods for characterizing an organic compound.

• Crystallography: This is the most precise method; however, it is very difficult to grow crystals of sufficient size and high quality to get a clear picture, so it remains a secondary form of analysis.
• Elemental Analysis: A destructive method used to determine the elemental composition of a molecule.
• Infrared spectroscopy: Chiefly used to determine the presence (or absence) of certain functional groups.
• Mass spectrometry: Used to determine the molecular weight of a compound and the fragmentation pattern.
• Nuclear magnetic resonance (NMR) spectrometry
• UV/VIS spectroscopy: Used to determine degree of conjugation in the system

Organic reactions are chemical reactions between organic compounds.