Organic+Chemistry

[|Organic compounds] are structurally diverse. The range of application of organic compounds is enormous. They either form the basis of, or are important constituents of, many products including [|plastics], [|drugs], [|petrochemicals], [|food], [|explosives], and [|paints]. They form the basis of almost all [|earthly life] processes (with very few exceptions). Since organic compounds often exist as [|mixtures], a variety of techniques have also been developed to assess purity, especially important being [|chromatography] techniques such as [|HPLC] and [|gas chromatography]. Traditional methods of separation include [|distillation], [|crystallization], and [|solvent extraction]. Organic compounds were traditionally characterized by a variety of chemical tests, called "wet methods", but such tests have been largely displaced by spectroscopic or other computer-intensive methods of analysis.[|[][|4][|]] Listed in approximate order of utility, the chief analytical methods are: Traditional spectroscopic methods such as [|infrared spectroscopy], [|optical rotation], [|UV/VIS spectroscopy] provide relatively nonspecific structural information but remain in use for specific classes of compounds.
 * Organic chemistry** is a subdiscipline within [|chemistry] involving the [|scientific] study of the structure, properties, composition, [|reactions], and preparation (by [|synthesis] or by other means) of [|carbon]-based compounds, [|hydrocarbons], and their derivatives. These compounds may contain any number of other elements, including [|hydrogen], [|nitrogen], [|oxygen], the [|halogens] as well as [|phosphorus], [|silicon], and [|sulfur].[|[][|1][|]][|[][|2][|]][|[][|3][|]]
 * [|Nuclear magnetic resonance (NMR) spectroscopy] is the most commonly used technique, often permitting complete assignment of atom connectivity and even stereochemistry using [|correlation spectroscopy]. The principal constituent atoms of organic chemistry - hydrogen and carbon - exist naturally with NMR-responsive isotopes, respectively 1H and 13C.
 * [|Elemental analysis]: A destructive method used to determine the elemental composition of a molecule. See also mass spectrometry, below.
 * [|Mass spectrometry] indicates the [|molecular weight] of a compound and, from the [|fragmentation patterns], its structure. High resolution mass spectrometry can usually identify the exact formula of a compound and is used in lieu of elemental analysis. In former times, mass spectrometry was restricted to neutral molecules exhibiting some volatility, but advanced ionization techniques allow one to obtain the "mass spec" of virtually any organic compound.
 * [|Crystallography] is an unambiguous method for determining [|molecular geometry], the proviso being that single crystals of the material must be available and the crystal must be representative of the sample. Highly automated software allows a structure to be determined within hours of obtaining a suitable crystal.

Properties
Physical properties of organic compounds typically of interest include both quantitative and qualitative features. Quantitative information includes melting point, boiling point, and index of refraction. Qualitative properties include odor, consistency, solubility, and color.

Melting and boiling properties
In contrast to many inorganic materials, organic compounds typically melt and many boil. In earlier times, the melting point (m.p.) and boiling point (b.p.) provided crucial information on the purity and identity of organic compounds. The melting and boiling points correlate with the polarity of the molecules and their molecular weight. Some organic compounds, especially symmetrical ones, sublime, that is they evaporate without melting. A well known example of a sublimable organic compound is [|para-dichlorobenzene], the odiferous constituent of modern mothballs. Organic compounds are usually not very stable at temperatures above 300 °C, although some exceptions exist.

Solubility
Neutral organic compounds tend to be hydrophobic, that is they are less [|soluble] in water than in organic solvents. Exceptions include organic compounds that contain ionizable groups as well as low [|molecular weight] [|alcohols], [|amines] , and [|carboxylic acids] where [|hydrogen bonding] occurs. Organic compounds tend to dissolve in organic [|solvents]. Solvents can be either pure substances like [|ether] or [|ethyl alcohol], or mixtures, such as the paraffinic solvents such as the various [|petroleum ethers] and [|white spirits] , or the range of pure or mixed aromatic solvents obtained from petroleum or tar [|fractions] by physical separation or by chemical conversion. Solubility in the different solvents depends upon the solvent type and on the [|functional groups] if present.

Solid state properties
Various specialized properties of [|molecular crystals] and [|organic polymers] with [|conjugated systems] are of interest depending on applications, e.g. thermo-mechanical and electro-mechanical such as [|piezoelectricity], electrical conductivity (see [|conductive polymers] and [|organic semiconductors] ), and electro-optical (e.g. [|non-linear optics] ) properties. For historical reasons, such properties are mainly the subjects of the areas of [|polymer science] and [|materials science].

Polymers
This swimming board is made of [|polystyrene], an example of a polymer. One important property of carbon is that it readily forms chains, or networks, that are linked by carbon-carbon (carbon to carbon) bonds. The linking process is called [|polymerization], while the chains, or networks, are called [|polymers]. The source compound is a called [|monomer]. Two main groups of polymers exist: [|synthetic polymers] and [|biopolymers]. Synthetic polymers are artificially manufactured, and are commonly referred to as [|industrial polymers]. [|[5]] Biopolymers occur within a respectfully natural environment, or without human intervention. Since the invention of the first synthetic polymer product, [|bakelite], synthetic polymer products have frequently been invented.[// [|citation needed] //] Common synthetic organic polymers are [|polyethylene] (polythene), [|polypropylene], [|nylon] , [|teflon] (PTFE), [|polystyrene] , [|polyesters] , [|polymethylmethacrylate] (called perspex and plexiglas), and [|polyvinylchloride] (PVC).[// [|citation needed] //] Both synthetic and natural [|rubber] are polymers.[// [|citation needed] //] Varieties of each synthetic polymer product may exist, for purposes of a specific use. Changing the conditions of polymerization alters the chemical composition of the product and its properties. These alterations include the [|chain length], or [|branching] , or the [|tacticity] .[// [|citation needed] //] With a single monomer as a start, the product is a [|homopolymer] .[// [|citation needed] //] Secondary component(s) may be added to create a [|heteropolymer] (co-polymer) and the degree of clustering of the different components can also be controlled.[// [|citation needed] //] Physical characteristics, such as hardness, [|density], mechanical or [|tensile strength] , abrasion resistance, heat resistance, transparency, colour, etc. will depend on the final composition.