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Topic: Optical isomerism

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Chirality (chemistry)

Geometric isomerism

Enantiomer

Isomer

Cahn Ingold Prelog priority rules

Mirror image

Stereoisomerism

Stereochemistry

Virtual image

Chirality

Amino acid

Vitamin C

Alanine

Amine

Optical isomerism - Wikipedia, the free encyclopedia Optical isomerism is a form of isomerism (specifically stereoisomerism) where the two different isomers are the same in every way except being non-superposable Via a magneto-optic effect, the (-)-form of an optical isomer rotates the plane of polarization of a beam of polarized light that passes through a quantity of the material in solution counterclockwise, the (+)-form clockwise. One example is the amino acid alanine: alanine has two optical isomers, and they are labeled according to which isomer of glyceraldehyde they come from. en.wikipedia.org /wiki/Optical_isomerism   (1906 words)

isomer on Encyclopedia.com Isomers are classified as structural isomers, which have the same number of atoms of each element and molecular weight but different bonding patterns (see chemical bond), or as stereoisomers, which have the same number of atoms of each element, molecular weight, and bonding pattern but in which the atoms have different spatial relationships. Optical isomers of a given compound are often identical in all physical properties except the direction in which they rotate light. ISOMER [isomer], in chemistry, one of two or more compounds having the same molecular formula but different structures (arrangements of atoms in the molecule). www.encyclopedia.com /html/i1/isomer.asp   (1186 words)

Isomerism However, the amount of optical rotation is not constant for an individual enantiomer but rather is dependent on the solvent, concentration, temperature, the wavelength of light used, and the path length of the sample cell employed to determine the rotation. Most optically active drugs are chiral as a result of the presence of an asymmetrically substituted tetrahedral carbon atom. Thus, the RS isomer is a diastereomer of the RR and SS isomers, and the SS isomer is a diastereomer of the RS and SR isomers. www.dekker.com /sdek/92657250-22271917/abstract~db=enc~content=a713491664~words=   (3381 words)

bk7 In the (E) or “trans” isomer, the “methyl groups”, (CH are on opposite sides of C=C, whereas in the (Z) or “cis” isomer, a different geometry pertains in which the “methyl groups” are on the same side of C=C. The final type of isomerism, “optical isomerism” is the most challenging for students. The "non-superimposibility" of 9 upon 10 or vice versa, is the one true test of "optical isomerism". Thus, obtaining colorless crystals of an “optically active” substance (substance with an optical rotation), and the finding if the structure of the substance is in fact 3 or 4 is an arduous task. www.chem.unl.edu /cak/ch7.htm   (3078 words)

CHEM2P32 Lecture 7: Stereoisomers of Metal Complexes The cis-cis-cis geometric isomer of MA is chiral. Isomer C: one chloride is trans to a middle nitrogen, the other is trans to a terminal nitrogen. The three isomers place A trans to C, A trans to B, and A trans to D. None of these is chiral (the square plane is the plane of symmetry in these complexes). chemiris.labs.brocku.ca /~chemweb/courses/chem232/CHEM2P32_Lecture_7.html   (887 words)

CHEM2P32 Lecture 6: Structural Isomers However, there are instances of chirality and optical isomerism that do not depend on having four different groups attached to a tetrahedral central atom. Optical isomers get their names because they are able to rotate a plane-polarized light beam to the left or to the right. Isomer B does not react with barium chloride but gives a white precipitate of AgCl when a solution of silver nitrate is added to it. chemiris.labs.brocku.ca /~chemweb/courses/chem232/CHEM2P32_Lecture_6.html   (1045 words)

Stereoisomerism - Psychology Central Optical isomers are stereoisomers formed when asymmetric centers are present, for example, a carbon with four different groups bonded to it. For example a geometrical isomerism occurs when a double bond is present, because the pi bond involved prevents that bond from being "twisted" the same way that a single bond can be. Compounds that are enantiomers of each other have the same physical properties, except for the direction in which they rotate polarized light and how they interact with different optical isomers of other compounds. psychcentral.com /psypsych/Stereoisomer   (371 words)

Stereoisomers : Stereoisomerism : Optical isomerism. Optical isomers are stereoisomers since the atoms are connected in the same order but the arrangement of the atoms in space is different. Optical isomerism can occur in compounds with four different groups arranged around a carbon atom. Optical isomerism occurs in other compounds such as transition metal complexes. scholar.hw.ac.uk /site/chemistry/topic5.asp?outline=no   (410 words)

optical isomerism For example, one of the optical isomers (enantiomers) of the amino acid alanine is known as (+)alanine. Optical isomers are named like this because of their effect on plane polarised light. Isomers are molecules that have the same molecular formula, but have a different arrangement of the atoms in space. www.chemguide.co.uk /basicorg/isomerism/optical.html   (1487 words)

Organic Isomers Optical isomerism occurs when substances have the same molecular and structural formulae, but one cannot be superimposed on the other. Optical isomers have the same chemical and physical properties, except that one structure rotates the plane of polarized light to the right and the other rotates it to the left. Positional isomerism, another type of structural isomerism, occurs when functional groups are in different positions on the same carbon chain. www.silcom.com /~adbrown/chem102/organic_isomers.htm   (1030 words)

Stereoisomers : Stereoisomerism : Optical isomerism. : Biological systems. Optical isomerism is immensely important in biological systems. For example, when the amino acid alanine is synthesised in the laboratory, a mixture of the two possible isomers (a racemic mixture) is produced (Figure 15). Only the isomer of alanine with structure 2 (Figure 16) occurs naturally in organisms such as humans. scholar.hw.ac.uk /site/chemistry/topic6.html   (203 words)

isomerism --  Britannica Concise Encyclopedia - The online encyclopedia you can trust! Geometric isomerism results from rigidity in the molecular structure; in organic compounds this rigidity most often is associated with a double bond or a ring of atoms. It is now generally accepted that the differences in the properties of isomers result from differences in the arrangements of atoms within the molecules, but at the time (1830) that isomerism was recognized and named (by the Swedish chemist Jöns Jakob Berzelius), even the existence of molecules was not well established. Optical isomers occur in pairs that are nonsuperimposable mirror images of each other, like right- and left-handed gloves. www.britannica.com /ebc/article-9042954   (1289 words)

Optical Isomerism A very important feature of the structure of amino acids (and other kinds of compounds as well, for that matter) is called optical isomerism. Consequently, this central atom is not an asymmetric carbon atom, the molecule is not an optically active molecule, and these are identicalcompounds and not optical isomers. Optically, there is also that difference which will be pointed out when we deal with carbohydrates in a later lesson. dl.clackamas.cc.or.us /ch106-05/optical.htm   (635 words)

Re: Are connecticivty and optical rotation enough information to uniquely Optical isomerism is not the only type of ambiguity for a system with fixed connectivity. To summarize: connectivity and optical rotation are not sufficient to uniquely specify a molecular structure because of (1) geometric isomerism involving C=C (and C=N) double bonds, or (2) possible coincidence of similar rotation for diastereomers (3) possibility of more than one zero rotation meso- form for a given potentially chiral connectivity. Even with optical isomers, things can get rather complicated when there is more than one chiral carbon atom in the structure. www.madsci.org /posts/archives/2004-02/1076951641.Ch.r.html   (464 words)

A2 unit chains and rings and spectroscopy nitrogen compounds page Optical isomerism occurs as a result of a molecule having a mirror image that is non-superimposable on it. Isomers of a molecule that result from a difference in the arrangement of groups in 3-D space, and not in the type and/or position of covalent bonds, are known as stereoisomers. When light that has been polarized, so that it travels in only one plane, is shone on an optical isomer and the isomer is rotated, at a particular angle the light is absorbed. www.rjclarkson.demon.co.uk /candrands/nitrogen.htm   (1034 words)

Daily Assignments 11/29 optical isomers in metal complexes - a miniquiz www.wellesley.edu /Chemistry/chem120/nov29.html   (8 words)

Isomerism Optical isomerism is the same type of thing the two molecules mirror each other. Optical isomerism is more commonly known as chiral isomers, or as chirality. This type of isomerism is usually seen in molecules which either are square planner or have a double bond. www.chem.shef.ac.uk /chm131-2002/cha02cs/steroisomerism.html   (566 words)

CyberEd® PLATO Science :: Science Education Software Optical isomerism is a difficult concept to describe in two-dimensional formats. Explain that an asymmetric carbon atom is chiral, that it gives rise to optical isomers, and that such isomers exist as mirror images and differ only in their effect on plane-polarized light. Identify cis-trans isomers as examples of geometric isomerism and explain that these are caused by restricted rotation about a carbon-carbon double bond. www.cybered.net /commerce.asp?CatId=311&ProdId=X5005110   (288 words)

DictO9.html ] An optical instrument for measuring distance, usually from its position to a target point, by measuring the angle between rays of light from the target, which enter the rangefinder through the windows spaced apart, the distance between the windows being termed the baselength of the rangefinder; the two types are coincidence and stereoscopic. ] An optical instrument, consisting of a slit, collimator lens, prism or grating, and a telescope or objective lens, which produces an optical spectrum arising from emission or absorption of radiant energy by a substance, for visual observation. ] Any phenomenon of the atmosphere explained in terms of optical laws, such as a mirage or a halo. www.accessscience.com /Dictionary/O/O9/DictO9.html   (2702 words)

Isomerism in Coordination Compounds Optical isomers are related as non-superimposable mirror images and differ in the direction with which they rotate plane-polarised light. Optical isomers are possible for each of these 15 forms, making a total of 30 isomers. Note that, although it is predicted that tetrahedral complexes with 4 different ligands should be able to give rise to optical isomers (compare C chemistry), in general they are too labile and can not be isolated. wwwchem.uwimona.edu.jm:1104 /courses/IC10Kiso.html   (1242 words)

Isomerism in Organic Chemistry Isomerism is the phenomenon whereby certain compounds, with the same molecular formula, exist in different forms owing to their different organisations of atoms. The concept of isomerism illustrates the fundamental importance of molecular structure and shape in organic chemistry. Enantiomers have identical physical constants, such as melting points and boiling points, but are said to be optically active since they can be distinguished from each other by their ability to rotate the plane of polarised light in opposite directions. www.avogadro.co.uk /organic/isomer.htm   (266 words)

Introduction to Pharmaceutical Stereochemistry - London University School of Pharmacy Properties of optical isomers together with optical rotation are covered, as are compounds with more than one asymmetric carbon and the D and L labelling method. The student is introduced to the isomerism displayed by asymmetric carbon atoms, Fishcer notation and the representation of three dimensions as two. The student is introduced to cis- and trans- isomerism and there is an interactive test on whether certain compounds can exist as geometric isomers. www.le.ac.uk /tltp/catalogue/phase1/tom13201.htm   (430 words)

Ciencia y Tecnología A particular puzzle was the case of optical isomers, substances which appeared to be identical chemically and physically, except that one form rotated the plane of polarised light to the right and another to the left, while a third form seemed to be optically -inactive, with no effect on polarized light. Pasteur's discovery of the connection between optical activity and molecular chirality led him to suppose that the forces of nature are not mirror-symmetric. The main atomic and molecular expecuations from the electroweak interaction are, firstly, universal optical activity and, secondly, a difference between the electronic binding energy of two enantiomeric molecules in either a stationary or a transition state. cabierta.uchile.cl /revista/3/chirality.html   (2644 words)

Andrew M. Goldsweig's Enantiomer Page Cyclic compounds can be characterized by optical isomerism similar to their geometric isomerism. Thus, a racemic mixture, which is composed of equal amounts of each enantiomer of a compound, should exhibit no optical activity since the effects of the different isomers negate each other. Thus, if structures are manipulated according to these ideas, their isomerism can be noted. www-personal.umich.edu /~dgoldswe/mit/dcds/enantiomers.html   (449 words)

Biological systems A large number of biological molecules present optical isomerism. From an industrial point of view it would be of great interest to be able to separate optical isomers of type L from optical isomers of type D (or if your prefer optical isomers of type R from optical isomers of type S). This understanding may be useful to design chemical modifications of a molecule that allow to separate the optical isomers in the solid phase. www.ucm.es /info/molecsim/html.uk/invest/sistbio/sistbio.htm   (284 words)

CHM 103 GENERAL CHEMISTRY Racemic mixture: a 50:50 mixture of optical isomers. Geometric isomerism is caused by the rigidity of the carbon-carbon double bond. Cis-trans isomerism can be important in human metabolism and nutrition. www.ltcconline.net /stevenson/docs/CHM103LessonPlan20040615.htm   (823 words)

Stereochemistry (Cis-trans isomerism) two classes–geometrical isomerism and optical         such isomers is illustrated by Experiment 12-A. isomerism. The interconversion of the cis-trans isomers is         water in a small round-bottomed flask. When an aqueous solution of either isomer is             a sealed capillary tube. www.hartnell.cc.ca.us /faculty/shovde/chem12a/reportsheets/isomerism.htm   (551 words)

Isomerism - Stereoisomerism in Organic Chemistry GCE-AS-A2-K12 Stereoisomerizm Geometrical and Optical at Doc Brown's Chemistry Clinic. revision,revise,revising,teach,teaching,learn,learning btisomerism2bwpb wpbchemhelp Isomerism - Stereoisomerism in Organic Chemistry GCE-AS-A2-K12 Stereoisomerizm Geometrical and Optical at Doc Brown's Chemistry Clinic. only one optical isomers might be able to 'dock' successfully or only one optical isomer is formed. The diagram of the 'key and lock' mechanism is obviously presented in 2D, but in reality, it is a 3D situation and e.g. www.wpbschoolhouse.btinternet.co.uk /page07/isomerism2b.htm   (6029 words)

Freelance Traveller - The Lab Ship - Xenobiology 101 - From Primordial Soup to Cells Where optical isomerism is possible, in time one form will dominate over another because to catalyse reactions with the other isomer requires more energy. One theory suggests that a small excess of one isomer, created by an abundance of circularly polarised light (common in star forming regions), and subsequent amplification by later chemical reactions, did the trick. Almost all sugars are D isomers (gut membrane glucose transporters will accept L-glucose with 1% of the avidity of the D form - but most organisms can't do anything with L-glucose). www.freelancetraveller.com /features/science/xbio101/xbio2.html   (1605 words)

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