The delocalization of the electrons in benzene can best be shown by showing benzene with a ring inside the hexagon, with the hydrogen atoms understood. Delocalization of the electrons makes for a more stable molecule than a similar molecule that does not have delocalized electrons. Benzene is a more stable and less reactive compound than straight-chain hexenes. There are many derivatives of benzene. The hydrogen atoms can be replaced by many different substituents.
Aromatic compounds more readily undergo substitution reactions than addition reactions; replacement of one of the hydrogen atoms with another substituent will leave the delocalized double bonds intact.
The following are typical examples of substituted benzene derivatives:. Toluene and xylene are important solvents and raw materials in the chemical industry. Styrene is used to produce the polymer polystyrene. The figure below shows the structural formulas for vanilla and naphthalene. Naphthalene is a chemical which is commonly used in mothballs.
The vanilla molecule is extracted from vanilla beans. The simplest aromatic compounds are benzene rings with one substituent replacing one of the hydrogen atoms. If this substituent is an alkyl group, it is named first, followed in one word with "benzene".
The molecule shown below is therefore called ethylbenzene. Substituents can be groups other than alkyl groups. If a chlorine atom were substituted for a hydrogen, the name becomes chlorobenzene. If more than one substituent is present, their location relative to each other can be indicated by numbering the positions on the benzene ring.
The number of the carbon location then precedes the name of the substituent in the overall name, with the numbers separated by a comma. Molecules containing pyrrole occur in a number of important biological systems, ranging from photosynthesis to oxygen transport in the blood. See Porphine , Heme , and Chlorophyll below. I know you're out there, I can hear you breathing. Porphine 3D Download 3D Porphine contains four pyrrole molecules which have been joined to form a larger ring system.
This molecule has 18 p electrons in the ring system, and is therefore aromatic. Like other aromatic molecules, this ring system is especially stable. The ring system is flat, since all of the carbon and nitrogen atoms in the ring are sp 2 -hybridized, and therefore trigonal planar in shape.
This leaves the molecule with a large open cavity in the center, with four nitrogen atoms pointing towards the center of the cavity. Porphine is the parent compound of a class of molecules called the porphyrins , in which various substituents replace the hydrogen atoms on the outside of the porphine ring. The name "porphyrin" is derived from the fact that many of these substances form purple crystalline solids the Greek word for "purple" is "porphyros".
Porphyrins occur ubiquitously in nature, especially in systems involving respiration see Heme and Chlorophyll below. The protein hemoglobin contains four subunits two "alpha" and two "beta" subunits , each of which complex a heme molecule; this protein is responsible for oxygen transport in the body. The iron atom in heme forms complexes with oxygen molecules, which are carried throughout the body by the hemoglobin in the red blood cells. Chlorophyll 3D Chlorophyll Greek, chloros "green" and phyllon "leaf" is a porphyrin derivative found in green plants and cyanobacteria which allows these organisms to perform photosynthesis.
Shown below are the structures of chlorophyll a and chlorophyll b ; the magnesium-free forms of these molecules are called pheophytin a and pheophytin b. The three-dimensional structure shown on the right is that of pheophytin a. A double bond in one of the pyrrole rings in the porphyrin macrocycle is reduced to a single bond in the structure below, this is the carbon-carbon bond to which the long side-chain, sometimes called the phytyl group, is attached ; these "dihydroporphyrins" are known as chlorins.
The energy from the sunlight that is absorbed by chlorophyll in the chloroplasts of green plants is used to drive the synthesis of carbohydrates such as glucose C 6 H 12 O 6 from carbon dioxide and water:. This equation summarizes a lot of complex chemistry, which it is beyond the scope of this page to try to summarize. In the fall, the green color of many plants disappears as the chlorophyll starts to break down; this allows other pigments, such as carotenes, in the leaves to "show their colors," producing the vivid yellows and oranges associated with fall colors.
Buckminsterfullerene , or C 60 , is a soccer-ball shaped molecule consisting of 60 carbon atoms. The molecule was discovered by H. Kroto, R. Smalley, and R. Curl in the s in experiments involving graphite vaporized with lasers they were awarded the Nobel Prize in Chemistry for their discovery in The structure, a truncated icosahedron, having 12 pentagons and 20 hexagons, reminded them of the shape of the geodesic dome designed by the architect R. Buckminster Fuller, and they named the molecule in his honor.
Similar spherical-shaped carbon-only molecules, such as C 70 , are often referred to as fullerenes or "buckyballs. The fullerenes are considered another allotrope stable structural form of carbon, in addition to graphite and diamond. In the s it was discovered that C 60 could be made in larger quantities by heating graphite in an inert atmosphere.
Since then, these molecules have been intensely investigated. Nanotubes are cylindrical versions of the fullerenes; they look something like a chain link fence rolled into a cylinder, with a dome-shaped cap on the end half of a buckyball.
Nanotubes also known as "buckytubes" are extremely strong, as well as being very lightweight since they are made of nothing but carbon atoms. These materials are being tested for potential use in many materials; some nanotubes also conduct electricity, leading to some potential applications in circuit design and electronics. C 70 3D Download 3D C 70 is another example of a fullerene.
It has a slightly elongated, oval shape. Atkins, Molecules , 2nd ed. Cambridge: Cambridge University Press, , p. Paula Yurkanis Bruice, Organic Chemistry , 4th ed. Upper Saddle River: Prentice Hall, , p. Marye Anne Fox and James K. Whitesell, Organic Chemistry , 3rd ed.
Sudbury: Jones and Bartlett Publishers, p. Maitland Jones, Jr. New York: W. Richard J. Lewis, Sr. New York: Van Nostrand Reinhold, Englewood Cliffs: Prentice Hall, , p.
Royston M. Roberts, Serendipity: Accidental Discoveries in Science. Sharp, The Penguin Dictionary of Chemistry , 2nd ed. London: Penguin Books, Wade, Jr. Martha Windholz ed. Benzene 3D Download 3D Benzene was first isolated by Michael Faraday in , from the whale oil used in gaslights; he also determined that it had an empirical formula of CH. Amygdalin Laetrile 3D Download 3D Amygdalin is a disaccharide consisting of two glucose molecules in which a carbon bearing a cyano CN group and a benzene ring is attached to one of the oxygen atoms on a glucose.
Hyacinthin 3D Download 3D Hyacinthin is commonly used in perfumes; it is responsible for the floral scent found in hyacinth oddly enough. Cinnamaldehyde 3D Download 3D Cinnamaldehyde is found in oil of cinnamon, which is found in the bark of the cinnamon tree. Naphthalene 3D Download 3D Naphthalene is a white crystalline solid, derived from coal tar, with a characteristic odor of mothballs — which is not a coincidence, since naphthalene is frequently used in mothballs.
Pyridine 3D Download 3D In the pyridine molecule, one of the CH groups of the benzene ring is replaced with a nitrogen atom. OUT on pyrrole. The energy from the sunlight that is absorbed by chlorophyll in the chloroplasts of green plants is used to drive the synthesis of carbohydrates such as glucose C 6 H 12 O 6 from carbon dioxide and water: This equation summarizes a lot of complex chemistry, which it is beyond the scope of this page to try to summarize.
Download 3D. Buckminsterfullerene 3D Download 3D Buckminsterfullerene , or C 60 , is a soccer-ball shaped molecule consisting of 60 carbon atoms. Navigation Bar. Molecule Gallery. Toluene or methylbenzene is a commonly used organic solvent; it is less carcinogenic than benzene because the methyl group is easily oxidized, and can be converted to products that can be eliminated from the body with relative ease. There are three structural isomers of the xylenes , which have two methyl groups on the benzene ring.
Aniline is a colorless, oily liquid. Phenol is a mild acid in aqueous solution where it is known as carbolic acid , and was originally used as a disinfectant in hospitals. Benzoic Acid. Benzoic Acid is is a white, crystallize solid at room temperature. Styrene consists of a benzene ring connected to a carbon-carbon double bond. Benzaldehyde consists of a benzene ring connected to an aldehyde group a carbon-oxygen double bond bearing a hydrogen, —CHO. Amygdalin Laetrile.
Anethole is found in oil of aniseed, fennel, and tarragon. Benzyl acetate. Benzyl acetate is one of the compounds found in oil of jasmine, which is a common ingredient in perfumes and toiletries.
Phenylethanol is found in oil of citronella, geraniums, and with geraniol is partially responsible for the odor or roses. Anthracene is a white crystalline solid which exhibits a blue fluorescence under ultraviolet light. Phenanthrene is a structural isomer of anthracene, in which the three benzene rings are fused to make an angle. Dibenz[ a,h ]anthracene.
Dibenz[ a,h ]anthracene is a carcinogenic compound found in tobacco smoke and automobile exhaust. Benzo[ a ]pyrene. Benzo[ a ]pyrene is a carcinogenic compound found in tobacco smoke and automobile exhaust. Methyl 2-pyridyl ketone. Methyl 2-pyridyl ketone is one of the main components in the odor of popcorn. In the pyrazine molecule, two CH groups on opposite sides of the benzene ring are replaced by nitrogen atoms.
In the pyrimidine molecule, two CH groups "meta" to each other in the benzene ring are replaced by nitrogen atoms. In the purine molecule, four nitrogen atoms are found in two fused rings.
Furan , which has an oxygen atom in a ring with four carbon atoms, is also an aromatic molecule; a lone pair of electrons on the oxygen contributes two electrons in addition to the four electrons from the carbon-carbon double bonds, making a total of six p electrons in the ring system.
Thiophene has a sulfur atom in a ring with four carbon atoms, and, like furan, is aromatic because there are six p electrons in the ring four from the double bonds and two from a lone pair on sulfur.
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