why is benzoin molecule not optically active even though it has a chiral center?
492829
Hmm, the alpha-hydroxy carbon (CHOH) in benzoin is chiral:\n\nC6H6-CHOH-C(O)-C6H6\n\nso there should be optical activity.  These journal articles indicate that benzoin is optically active:\n\nhttp://turmac13.chem.columbia.edu/PDF_db/publications_401_450/444.pdf\nhttp://www.garfield.library.upenn.edu/histcomp/born-m_auth-citing/index-tc-99.html#\n\nPerhaps, if you are measuring a sample of benzoin made in the lab, you have a racemic mixture of enantiomers.  That would explain a lack of measurable optical activity.
710899
Bromine would add to the double bond in the ring and to the double bonds in the methyl-vinyl group adjacent to the ring.\n\nIt would create 2 stereocenters and it would be racemic, because bromine is not enantioselective.
455412
In optics, optical rotation or optical activity is the rotation of linearly polarized light as it travels through certain materials. It occurs in solutions of chiral molecules (e.g. sugar), solids with rotated crystal planes (e.g. quartz), and spin-polarized gases of atoms or molecules. It is used in sugar industry to measure syrup concentration, in optics to manipulate polarization, in chemistry to characterize substances in solution, and is being developed as a method to measure blood sugar concentration in diabetic people.
907730
Since you made your question sound real with intent on getting an answer even if you don't except it I will try to explain.\nArthur Conan Doyle for his character Sherlock Holmes wrote and I quote loosely.. "You solve a mystery by removing posiblities. What ever is left no matter how improbable is the truth.."\nThat leads me to chirality. Although two chemical molecules may appear to have the same elements and similar properties, they can still have different structures. When two molecules appear \nidentical and their structures differ only by being mirror images of each other, those molecules are said to have chirality. Your left and right hands illustrate chirality. When a random chemical reaction is used to prepare molecules having chirality, there is an equal opportunity to prepare the left-handed isomer as well as the right-handed isomer. It is a scientifically verifiable fact that a random chance process, which forms a chiral product, can only be a 50/50 mixture of the two optical isomers. There are no exceptions. Chirality is a property that only a few scientists would even recognize as a problem. The fact that chirality was missing \nin those amino acids is not just a problem to be debated, it points to a catastrophic failure that "life" cannot come from chemicals by natural processes. If proteins and DNA were formed by chance, each and every one of the components would be a 50/50 mixture of the two optical isomers. This is not what we see in natural proteins or in natural DNA. How can a random chance natural process create proteins with thousands of "L" molecules, and then also create DNA with billions of "R" molecules? Does this sound like random chance or a product of design? Chirality is not just a major problem for evolution; it is a dilemma. It is this handedness that gives DNA the spiral shaped helical structure. If one molecule in the DNA structure had the wrong chirality, DNA would not exist in the double helix form, and DNA would not \nfunction properly. The entire replication process would be derailed like a train on bad railroad tracks. In order for DNA evolution to work, billions of molecules within our body would have to be generated with the "R" configuration all at the \nsame time, without error. If it is impossible for one nucleotide to be formed with chirality, how much less likely would it be for billions of nucleotides to come together exactly at the same time, and all of them be formed with the same chirality? According to evolution, natural processes must explain everything over long periods of time. However, the process that forms chirality cannot be explained by natural science in any amount of time.\nThis is evidence straight from the labs of Science. The Bible has nothing to do with these facts. Yet the magnitude of the problem indicates that there WAS a creative force behind all life and that the spontaneous life generation that most scientist hold up as fact is at best far fetched and worst impossible.....   Jim
727115
Optical isomerism is the phenomenon by which certain compounds rotate the plane of polarised ligth in a characteristic way when it is passes through their solutions.\nEnantiomers are stereoisomers that are related to each other as non-superimposable mirror images.Such stereoisomers differ only in the orientation in which they rotate the plane of polarised light.\nA mixture of two enantiomers in equal proportions have zero optical activity(racemic mixture)
598495
Between the two species, the BF3 is least likely to display resonance.  To resonate, on a chemical level, you must have two equivalent Lewis structures taht differ only in their arrangement of the electrons.  However, due to the structure of flouride ions, they are able to make one and only one bond.  Thus, no rearrangement is possible around the Boron center.  \n\nHowever, the Sulfate ion is a different story.  Both sulfur and oxygen have the ability to make multiple bonds with each other, giving the potential to have different combinations of bonds that are isoelectronic (electronically equal to one another).  So, this species would be more likeley to have resonance.  \n\nHope it helps.
1154935
methyl3-benzoyloxy-8-methyl-8-azabicyclo [3.2.1]octane-4-carboxylate  (thats the systematic name)\n\nFormula: C17H21NO4
798882
no it doesnt.........its IUPAC NAME is 2,3-dihydroxypropanal which suggets that it has a linear structure with  only three carbon atoms with an alcoholic group at the 2 n 3 carbon atom and with a carbonyl group (aldehyde gropu in this case) as the terminal carbon atom\nA compound will have a cyclic structure only if its a cycloalkane , cycloalkene or an aromatic compound.........since glyceraldehyde is none of the above..........its evident that its got a linear structure.
796830
The other 2 are cis-trans isomers. Notice that Dibenzalacetone has 2 double bonds so it can form a maximum of 2^2 isomers. But it is a symmetrical molecule, 2 of the isomers(cis and trans, trans and cis) are the same if you rotate the molecule. The isomers have different mp.\nSelf condensation of acetone can occur. But if no excess acetone is added, this is really unlikely to occur, isomerism should be the major factor accounting for the other 2 side products
704177
Meso compounds cannot rotate plane-polarized light, because they have planes of symmetry, so they are "internally compensated." They cannot exist as nonsuperimposable mirror images of one another. Example: Tartaric acid, d, l, and meso.
649568
It helps in the transfer of electrons in the condensation of certain compounds.  Since your last question was about benzoin, i assume you're talking about this as well.  Check the reaction scheme here:\n\nhttp://www.monomerchem.com/benzoin.html
323326
The "L" in L-Dopa refers to "levorotatory", meaning that the molecule rotates plane polarized light counterclockwise. The "L" is sometimes written as (-). The opposite is dextrorotatory ("D" or "+"), which rotates plane polarized light clockwise.\n\nYou cannot use "L" to predict whether the molecule is an "S" or an "R" enationmer. They are seperate things.\n\nThe "R" and "S" refer to the arrangement of the atoms around the chiral center. The "L" and "D" refer to the direction that the molecule rotates plane polarized light. All chiral carbons will therefore carry an "R/S" and a "D/L" distiction, but both indicate different things.\n\nYou did the correct thing in determining the R/S configuration by assigning priorities to the 4 groups connected to the chiral carbon and so on and so forth. The L/D distinction can only be determined experimentally.
390255
i presume you mean cyclohexanone (since cyclohexanol is not a carbonyl compound, it is an alcohol).\n\nBF3 is a Lewis acid, and the B has an empty p-orbital.  The lone-pair of electrons from the carbonyl will form a dative bond with the B by donating both the electrons to this bond.  This increasese the dipole on the C=O double bond making the C more available to nucleophilic attack (remember that the C in carbonyl compounds is slightly electropositive and the O slightly electronegative).  \n\nThe mechanism is the same on any carbonyl compound, so nothing specific for cyclohexanone.\n\nHope this helps
452453
No, we don't use the electronegativity chart; instead we draw the full structure of the molecule and then see which 'pulling of bonds' cancel each other. \nIn the molecule AsF3, since As has 5 outer most electrons(in group 5), each F is bonded to As with a single covalent bond. Hence, the shape of the molecule becomes trigonal pyramidal, with 3 bond pairs (with 3 F atoms) and 1 lone pair. The 3 bond pairs pull the electrons towards themselves in the lower plane, while the 1 lone pair pulls at the top. The pulling effect of the 2 F atoms at the 2 sides cancel out  because the pulling effect is the same for both F atoms; however, the pulling effect of the lone pair at the top and the 1 F bond pair at the bottom will not cancel, because it is not from the same atom/species. Hence the overall dipole moment( dipole moment = charge x distance) does not cancel out, so the molecule is polar, with some charge distribution remaining due to the unequal pulling effect.\n\nIn CF3Cl, the shape is tetrahedral, with the 3 Cl atoms and 1 F atom bonded by single covalent bonds to the central C atom. The bond pairs spread out with the 3 Cl atoms pulling at the bottom and the 1 F atom pulling at the top. The pulling effect of the 2 Cl atoms at the sides cancels out, but that of the F atom at the top and the Cl atom at the bottom does not, as the pullin effect of 2 different atoms is different. Hence, as before, overall dipole does not cancel and the molecule is hence polar.
898657
Answer is d..\n\nThe reaction is as follows:\n\nR-O- + R-X → R-O-R + X- \n\nwhere X is an halogen and R should not be cyclic.
1058187
for a rigid rotor, the transition lines are equally spaced in the wavenumber space. However, this is not always the case, except for the rigid rotor model. \n\nfor non-rigid rotor model, we need to consider changes in the moment of inertia of the molecule due to centrifugal distortion and the effects of vibration on the rotation.\n\nthe formulas are hard to write here, better to look at the references in \nhttp://en.wikipedia.org/wiki/Rotational_spectroscopy\nor elsewhere.
419119
The chiral organization of molecules (and other matter) is a frequently occurring phenomenon in our universe.  In Earth's early history, conditions were right (a large variety of atoms in the primordial soup, perfect temperature etc) to produce billions and billions of chirally organized combinations of molecules.   All that is needed for life to begin is a charged lipid micelle (common in Earth's early oceans) to absorb just one correctly organized chain and voila - the chain now has its closed environment complete with power source in which to sustain the electro-chemical reactions needed for life