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http://www.angelfire.com/scifi/WizardX/index.html
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thanks Wiz
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http://science.csustan.edu/stkrm/Recipes/Recipes-Lucas.htm
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http://nlfaculty.dcccd.edu/logan/slides/chapter10/sld026.htm
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Also:
Anhydrous Acids and Lewis Acids
Lewis acids are those which cannot provide a proton to another molecule but clearly react with bases. Like the proton itself, they are clearly in need of electrons. Their love of electrons has resulted in their being called "electrophiles". Although we generally use the term "electrophile" when no H+ is involved, it is also correct to call protic acids "electrophiles"
AlCl3 and FeCl3
Aluminum chloride has a central aluminum atom which has only 6 electrons; like boron in the acidic BF3, it is very electron-deficient. It is one of the stronger and more common Lewis acids used in chemistry. In the presence of alkyl halides (tertiary best, of course) or acyl halides, it can remove the halide to generate a carbocation (why are they stable?) and AlCl4-. The carbocation will react with whatever is available, even add to an aromatic ring. With carbons that are less able to support a positive charge, the aluminum chloride just loosens the C-Cl bond enough to make the carbon positive enough to react with the aromatic ring (and to rearrange as if it were a carbocation). Aluminum chloride is a powerful dehydrating agent as well, although not very selective; partially hydrated (to reduce its acidity) it works very well as commercial dehydrating agent - the antiperspirant aluminum chlorhydrate.
Ferric chloride is the catalyst of choice for halogenating benzene rings. The reaction proceeds like that of alkyl halides with aluminum chloride, namely polarization to remove a halide to form FeCl4-, and thus generating Cl+. An easy way to do this reaction is just to add powdered iron to the reaction and an excess of halogen; the halogen oxidizes the Fe to FeX3 (where X could be other halogens as well) which then catalyzes the reaction.
ROH2+
All oxygen-containing organic compounds, like alcohols, behave as bases in the presence of concentrated aqueous acids or anhydrous Lewis acids. Depending on what else is present, the temperature and the acid concentration, alcohols can be converted to ethers (one water lost for two molecules of alcohol) or alkenes (one molecule of water lost per molecule of alcohol). When acid and alcohol are added to other oxygen-containing compounds like ketones and acids and esters, they share the proton in equilibrium. The protonation of the oxygen makes the carbonyl carbon more susceptible to attack by nucleophiles in each case; however, any nucleophile that you use must be no more basic than the alcohol or carbonyl compound or it will be protonated instead! If just the carbonyl compound, alcohol and acid are present, ketones and aldehydes undergo addition to produce hemiacetals and acetals, although they are easily converted back to the aldehyde or ketone in the presence of water in most cases. With esters, acids and acid chlorides, the final product of reaction with acid and alcohol is an ester (perhaps a different ester if you start with an ester) via an addition - elimination sequence.
HX (HCl, HBr, HI) and Substitutes
The hydrohalic acids are gases and thus the aqueous "concentrated" solutions are not very concentrated; conc HCl, for example, is 35% in water. The high vapor pressure of the gaseous acid over the solution makes these acids very dangerous to work with, because the chances of exposure to the lungs is quite high. They are exceptionally good at corroding metals (my personal hypothesis is that the high vapor pressure is responsible).
Although HX's can be used for substituting alcohols with halide X, all sorts of side reactions occur with tertiary and secondary alcohols (rearrangement and dehydration). Better methods for substitution are: thionyl chloride (SOCl2) or PCl3, and for secondary and tertiary, the Lucas reagent, which is HCl made more acidic and more chloride-rich by a high concentration of the Lewis acid ZnCl2 (the water is now overwhelmed). Conversion of a carboxylic acid to an acid chloride cannot be done with aqueous HCl (the more stable acid is favored), but must be done with anhydrous SOCl2 or PCl3.
Has anyone any knowledge of this route having been attempted in the literature?
