Chemical synthesis

Chemical synthesis

In chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions. In modern laboratory usage, this tends to imply that the process is reproducible, reliable, and established to work in multiple laboratories.

A chemical synthesis begins by selection of compounds that are known as reagents or reactants. Various reaction types can be applied to these to synthesize the product, or an intermediate product. This requires mixing the compounds in a reaction vessel such as a chemical reactor or a simple round-bottom flask. Many reactions require some form of work-up procedure before the final product is isolated.[1] The amount of product in a chemical synthesis is the reaction yield. Typically, chemical yields are expressed as a weight in grams or as a percentage of the total theoretical quantity of product that could be produced. A side reaction is an unwanted chemical reaction taking place that diminishes the yield of the desired product.

The word synthesis in the present day meaning was first used by the chemist Adolph Wilhelm Hermann Kolbe.

Contents

Strategies

Many strategies exist in chemical synthesis that go beyond converting reactant A to reaction product B. In cascade reactions multiple chemical transformations take place within a single reactant, in multi-component reactions up to 11 different reactants form a single reaction product and in a telescopic synthesis one reactant goes through multiple transformations without isolation of intermediates.

Organic synthesis

Organic synthesis is a special branch of chemical synthesis dealing with the synthesis of organic compounds. In the total synthesis of a complex product it may take multiple steps to synthesize the product of interest, and inordinate amounts of time. Skill in organic synthesis is prized among chemists and the synthesis of exceptionally valuable or difficult compounds has won chemists such as Robert Burns Woodward the Nobel Prize for Chemistry. If a chemical synthesis starts from basic laboratory compounds and yields something new, it is a purely synthetic process. If it starts from a product isolated from plants or animals and then proceeds to a new compounds, the synthesis is described as a semisynthetic process.

Other meanings

The other meaning of chemical synthesis is narrow and restricted to a specific kind of chemical reaction, a direct combination reaction, in which two or more reactants combine to form a single product. The general form of a direct combination reaction is:

A + B → AB

where A and B are elements or compounds, and AB is a compound consisting of A and B. Examples of combination reactions include:

2Na + Cl2 → 2 NaCl (formation of table salt)
S + O2SO2 (formation of sulfur dioxide)
4 Fe + 3 O2 → 2 Fe2O3 (iron rusting)
CO2 + H2OH2CO3 (carbon dioxide dissolving and reacting with water to form carbonic acid)

4 special synthesis rules:

metal-oxide + H2O → metal(OH)
non-metal-oxide + H2O → oxi-acid
metal-chloride + O2 → metal-chlorate
metal-oxide + CO2 → metal carbonate (CO3)

See also

References

  1. ^ Vogel, A.I., Tatchell, A.R., Furnis, B.S., Hannaford, A.J. and P.W.G. Smith. Vogel's Textbook of Practical Organic Chemistry, 5th Edition. Prentice Hall, 1996. ISBN 0582462363.

External links


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • chemical synthesis —       the construction of complex chemical compounds (chemical compound) from simpler ones. It is the process by which many substances important to daily life are obtained. It is applied to all types of chemical compounds, but most syntheses are… …   Universalium

  • chemical synthesis — cheminė sintezė statusas T sritis chemija apibrėžtis Vienų cheminių junginių gavimas iš kitų cheminių junginių ar cheminių elementų. atitikmenys: angl. chemical synthesis; synthesis rus. синтез; химический синтез ryšiai: sinonimas – sintezė …   Chemijos terminų aiškinamasis žodynas

  • Chemical biology — is a scientific discipline spanning the fields of chemistry and biology that involves the application of chemical techniques and tools, often compounds produced through synthetic chemistry, to the study and manipulation of biological systems.… …   Wikipedia

  • Chemical ligation — is a set of techniques used for creating long peptide or protein chains. It is the second step of a convergent approach. First, smaller peptides containing 30 50 amino acids are prepared by conventional chemical peptide synthesis. Then, they are… …   Wikipedia

  • Chemical substance — Chemical redirects here. For other uses, see Chemical (disambiguation). Steam and liquid water are two different forms of the same chemical substance, water. In chemistry, a chemical substance is a form of matter that has constant chemical… …   Wikipedia

  • Chemical decomposition — Chemical decomposition, analysis or breakdown is the separation of a chemical compound into elements or simpler compounds. It is sometimes defined as the exact opposite of a chemical synthesis. Chemical decomposition is often an undesired… …   Wikipedia

  • chemical compound — Introduction  any substance composed of identical molecules consisting of atoms (atom) of two or more chemical elements (chemical element).       All the matter in the universe is composed of the atoms of more than 100 different chemical elements …   Universalium

  • Chemical reaction — Chemical reactions redirects here. For the 2007 television episode, see Chemical Reactions (Men in Trees). A thermite reaction using iron(III) oxide. The sparks …   Wikipedia

  • Synthesis — The term synthesis (from the ancient Greek Polytonic|σύνθεσις σύν with and θέσις placing ) is used in many fields, usually to mean a process which combines together two or more pre existing elements resulting in the formation of something new.… …   Wikipedia

  • chemical reaction — Any chemical process in which substances are changed into different ones, with different properties, as distinct from changing position or form (phase). Chemical reactions involve the rupture or rearrangement of the bonds holding atoms together… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”