How did Louis Pasteur discover Chirality? How did he know that the molecules were chiral?
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The question was presented as an example of something puzzling - you have a substance - tartaric acid if i remember that is not optically active and then you have the same substance (but made as a result of microbial activity) that has identical properties, the only difference is that it is optically active - nobody then knew why\n\nhe let the optically inactive solution  crystalize, looked really close and well and compared - then noticed that the crystals differ - are like a miror image, he manually sorted them out and WOW the 2 solutions were optically active - the same degree but oposite direction (if you understand me, i do not know what this is called in english). then he assume that the microbes can do the sorting in their body. He spent his lifetime looking in microscopes or experimenting with unbelievable patience while enyybody else would have given up long time ago, thats why he made so many breakthroughs
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In the late nineteenth century, a German biochemist found the nucleic acids, long-chain polymers of nucleotides, were made up of sugar, phosphoric acid, and several nitrogen-containing bases. Later it was found that the sugar in nucleic acid can be ribose or deoxyribose, giving two forms: RNA and DNA. In 1943, American Oswald Avery proved that DNA carries genetic information. He even suggested DNA might actually be the gene. Most people at the time thought the gene would be protein, not nucleic acid, but by the late 1940s, DNA was largely accepted as the genetic molecule. Scientists still needed to figure out this molecule's structure to be sure, and to understand how it worked.\n\nIn 1948, Linus Pauling discovered that many proteins take the shape of an alpha helix, spiraled like a spring coil. In 1950, biochemist Erwin Chargaff found that the arrangement of nitrogen bases in DNA varied widely, but the amount of certain bases always occurred in a one-to-one ratio. These discoveries were an important foundation for the later description of DNA.\n\nIn the early 1950s, the race to discover DNA was on. At Cambridge University, graduate student Francis Crick and research fellow James Watson (b. 1928) had become interested, impressed especially by Pauling's work. Meanwhile at King's College in London, Maurice Wilkins (b. 1916) and Rosalind Franklin were also studying DNA. The Cambridge team's approach was to make physical models to narrow down the possibilities and eventually create an accurate picture of the molecule. The King's team took an experimental approach, looking particularly at x-ray diffraction images of DNA.
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In 1928, Scottish scientist Alexander Fleming. \n\nHe was trying to grow bacteria, bu tHe found that in the vessel that had penicilin, all the bacteria are dead, he tested it several times and finally he found the anti-bacterial power in penicillin. [Most probably he recvd Noble prize for this]\n\nSince then, the mankind is endowed with yet another strong weapon to fight bacteria.\n\nSay thanks to Flemming!
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If you're referring to spontaneous generation.  He had a contest with Felix Pouchet who believed in spontaneous generation.  Pasteur bent the necks of his flask so that dirt would be caught before it reached the broth and no bacteria arose.  This showed that bacteria were carried in dirt.
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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.
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The L and D prefixes concern how the molecule will rotate a plane of polarized light as it is passed through a tube containing a solution of the molecule.  \n\nThere is levorotary (left, "+") and dextrorotary (right, "-").  The "R" prefix is not used for optical activity, as there are "R" and "S" designations that pertain to the configuration of the molecule.  The actual physical structure of the molecule CANNOT be used to determine if a molecule is "L" or "D" , as both the "R" and "S" forms can rotate light in either direction depending on the molecule.\n\nIf there is a 50/50 mix of the "L" and "D" forms, then the molecule is said to have a "racemic" mixture and would just be noted by its name, e.g. glutamine.  It should be noted however that in naturally occurring amino acids, only the "L" form is found.  \n\nIf you buy amino acids, it is imperative that you buy the "L" form as the "D" form can have serious consequences including death.  To the best of my knowledge, the "D" form is illegal to sell for human consumption in the U.S.
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There are too many challenges in this molecule to come up with a synthesis in a few minutes.....1 chiral centre, 2 quartenary carbon centres next to each other, and geometrically specific double bonds.  However many syntheses have been completed.  The references below will direct you to published syntheses of analogues.  The first two are probably the most useful.\n\nTetrahedron, 1992, 8229-8238\nTetrahedron Letters, 1972, 2521-2524\nTetrahedron Letters, 1999, 6347-6351\nTetrahedron Letters, 1997, 1797-1800\nPhytochemistry, 1996, 23-28\nBioorganic and Medicinal Chemistry Letters, 1995, 275-278\nTetrahedron Letters, 1989, 1741-1744\nTetrahedron Letters, 1988, 5339-5342\n\nyou can access the journals through www.sciencedirect.com, but you may need to pay for them if your institution doesn't have access.\n\nhttp://cbr-rbc.nrc-cnrc.gc.ca/abscisicacid/\n\nAlso try the link above - gives you some more information.\n\nHope this helps.
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The discovery of oxygen
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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)
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The fundamental conception that underlay all Berthelot's chemical work was that all chemical phenomena depend on the action of physical forces which can be determined and measured. When he began his active career it was generally believed that, although some instances of the synthetical production of organic substances had been observed, on the whole organic chemistry must remain an analytical science and could not become a constructive one, because the formation of the substances with which it deals required the intervention of vital activity in some shape. To this attitude he offered uncompromising opposition, and by the synthetical production of numerous hydrocarbons, natural fats, sugars and other bodies he proved that organic compounds can be formed by ordinary methods of chemical manipulation and obey the same laws as inorganic substances, thus exhibiting the "creative character in virtue of which chemistry actually realizes the abstract conceptions of its theories and classifications--a prerogative so far possessed neither by the natural nor by the historical sciences."
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Then defend it... I say that there is no way that a random chance process could have formed life forming proteins and DNA with their unique chirality. 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? Even if \nthere were a magic process to introduce chirality, it would only create one isomer. If such a process existed, we do not know anything about it or how it would work. If it did exist, how were compounds with the other chirality ever formed? Even if there were two magical processes, one for each isomer, what determined which process  was used and when it was used, if this was a random chance natural process? The idea of two processes requires a controlling mechanism, and this kind of control is not possible in a random chance natural process.\nYou are an intelligent man alot smarter than a mere theist so I don't think I need to explain chirality more thoroughly. You just need to defend your statement... Too bad you can't now that you have this informant ion.....   Jim
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The Coriolis force was discovered in 1835 by French mathematician Gaspard-Gustave de Coriolis.  He noticed that there appeared to be a deflection force on moving objects in rotating reference frames.\n\nImportantly the Coriolis "force" is termed a "pseudo-force" by physicists because it only appears in non inertial (ie accelerating) reference frames.  Coriolis is actually just the action of inertia resisting the acceleration of the rotating frame.  Other examples of pseudo forces include centrifugal force and the acceleration due to gravity.\n\n\nHope this helps!\nThe Chicken
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Yes.  The easiest trick for determining polarity is to evaluate the electronegativity of the atoms.  Oxygen is more negative, while hydrogen is more positive.  If you write the partial charges on the atoms, you see that the charge balance is not equal.  If you had a molecule such as BCl4 (not real, just an example) the B is surrounded evenly by Cl atoms, so there is no polarirty
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What do you want to know?  He is considered the father of experimental chemistry.  He is credited with describing the Law of Conservation of Mass.
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It is Louis Pasteur. In France in the late 1870s, anthrax was a severe disease that destroyed flocks of sheep. This  influenced Louis Pasteur to direct his attention to the study of anthrax. He had just developed a regimen for heat attenuation of the causative agent of chicken cholera, and he used a similar approach in his studies of virulent anthrax bacilli. Cultures of the organism grown at elevated temperatures were shown to be decreased in virulence.\nIn historic field trials at Pouilly-le-Fort in 1881, Pasteur showed that these heat-attenuated organisms were capable of producing immunity against later challenge with virulent strains of the bacillus in animals. Pasteur is therefore given credit for developing the first vaccine effective in the prevention of anthrax.
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Check out this very straighforward website:\nhttp://en.wikipedia.org/wiki/Francesco_Redi\n\n"Pasteur boiled meat broth in a flask, heated the neck of the flask in a flame until it became pliable, and bent it into the shape of an S. Air could enter the flask, but airborne microorganisms could not - they would settle by gravity in the neck. As Pasteur had expected, no microorganisms grew. When Pasteur tilted the flask so that the broth reached the lowest point in the neck, where any airborne particles would have settled, the broth rapidly became cloudy with life." \nHere's a picture of this setup:http://en.wikipedia.org/wiki/Image:Ballon.gif\nBoth experiments disproved spontaneous generation (abiogenesis); Redi disproved it in larger organisms, and Pasteur disproved it in microorganisms.
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There is no way that Darwin could have been aware of the specific molecule we call deoxyribonucleic acid (DNA). In the mid-eighteenhundreds Friedrich Miescher isolated "nuclein" and then purified it.  The substance was identified as an acid and named as such the same century.  It wasn't until 1929 that the components of DNA were identified and 1937 that an x-ray structure of the polymer was available.  Many people worked at solving the problem (an x-ray structure of a molecule isn't a real "map" like you might think of with bones, its more like a series of clues from which you might "back out" the structure with much difficulty) and in 1953 James Watson & Francis Crick published the seminal Nature paper detailing their proposed structure for DNA, a double-helix with a phosphate backbone and nucleoside interior having set "patterns" of left-right pairing.  \n\nThis was almost 100 years after Charles Darwin published Origin of Species (1859).  Darwin's proposal of evolutionary processes stemmed from observations of the macroscopic natural world and was based not on chemistry but primarily on phylogeny.  Darwin's concepts were utilitarian-based similar to Lamarck's proposals, but differed by rejecting inheritability of aquired characteristics, instead favoring a model where beneficial intrinsic characteristics would arise on their own but predispose their bearers for greater survival & reproduction.  \n\nA contemporary with Gregor Mendel, at the time he wrote his famous Origin of Species, Darwin was not aware of the work of Mendel on inheritance of traits.  However, both scientists' work supported the same conclusions.