Which reagent is used in excess in the reduction of cinnamic acid by sodium borohydride and why?
152545
The borohydride will dispense a Hydride (H minus) to the carbonyl site causing the following transformation: R-COOH ---> R-CH2O- \n\nAdding the HCl will protonate the oxygen leaving you with: R-CH2OH
139601
This is an esterification, \nButanoic Acid (CH3CH2CH2CO2H)+ ethanol (HO-CH2CH3), in basic media, yields ethyl butyrate. \n\nCH3CH2CH2CO2H + HO-CH2CH3 --> CH3CH2CH2COO-CH2CH3
947695
H2S + 2NaOH --> Na2S + 2H2O\nMoles of H2S given = (1.19/34) = 0.035\nMoles of NaOH given = (4.91/40) = 0.12275\nFrom the chemical equation, 1 mole of H2S needs 2 moles of NaOH for complete reaction. Hence for 0.035 moles of H2S, you need only (0.035 x 2 = 0.07) moles of NaOH.\nThus the limiting reagent is H2S.\nFrom chemical equation, 1 mole of H2S produces 1 mole of Na2S. Thus moles of Na2S produced = moles of H2S used = 0.035\nMass of 0.035 mole of Na2S = mole x Mr of Na2S = 0.035 x 78 = 2.73g\n\nHope this helps :)
403780
GHB got a bum rap.  it's just more nonsense hysteria to justify the bloated budgets of the police state.\n\nThat aside, you don't convert beta to gamma.  suggesting an elimination failed to consider that the double bond formed will be more stable in conjugation with the carbonyl group; you'll get crotonic acid.  Subsequent hydrolysis would give you a mixture of alpha and beta.\n\nyou'd have much better luck trying to figure out a way to do it starting with GABA.\n\nOf course, if you have to ask, you lack the skilz.
367522
For pH3; Citrate buffer (Sodium citrate/citric acid) \n\nFor pH 8.75; Borate buffer (sodium tetraborate/boric acid), or TRIS [tris(hydroxymethyl)aminomethane]\n\nFor pH9.3; borate buffer, or carbonate buffer (carbonate/bicarbonate)
215160
http://www-ec.njit.edu/~skawinsk/chem243/chap11/chap11.htm\nthis may help–near the bottom
695914
Chemical laboratory supply houses carry it.  Try Alfa Aesar, they have it:\n\nhttp://www.alfa.com
757185
The Lewis or Brønstedt acid-catalyzed esterification of carboxylic acids with alcohols to give esters is a typical reaction in which the products and reactants are in equilibrium.\n\nThe equilibrium may be influenced by either removing one product from the reaction mixture (for example, removal of the water by azeotropic distillation or absorption by molecular sieves) or by employing an excess of one reactant.\n\nIf you want to reverse the equilibrium, add water or remove the alcohol.
292371
There is only one I can think of. 1-hexyne can be deprotonated with sodium in liquid ammonia, to yield a very basic, nucleophilic anion.\n\n2-hexyne has no such proton to remove.\n\n===\nThe poster below is also correct. NMR would be the fastest way. You wouldn't even have to use a deuterated solvent. (because the hexyne would be a liquid).
985537
Are you sure?  I do not believe NaOH is used in nylon synthesis.\n\nPerhaps you are referring to sodium hydride?  It is used in the production of nylon 6 (polycaprolactam).\n\nIf this is the case, then, sodium hydride is the initiator of the reaction. It reacts with caprolactam by extracting the amide hydrogen, to produce the sodium salt.
104161
You could rig a "Dean-Stark Trap" on the side of your condensor. That will eliminate water from your esterification (assuming its similar to the Fisher esterification) and force the production of more water and product, until one of the reagents is used up or an equilibrium is achieved.\n\nAnother method would be TLC, comparing the starting reaction mixture to the final product.\n\nSpectroscopy (NMR, IR) could be used.\n\nFinally, you could just put some of your sample into a GC-MS.
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The formula could be (C6H12OH)n, in which case it could be synthesised from the corresponding aldehyde. Expensiveness depends on how much and how pure of a product you want.
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1-Propanol. CH3CH=CH2 + B2H6 ===> CH3CH2CH2-BH2 ===> CH3CH2CH2-OH.\n\nDiborane always adds with the H on the more highly substituted carbon. This is the opposite of the Markovnikov rule during reaction with H2O and a little H2SO4, where the H goes to the less highly substituted carbon to give 2-propanol.
842140
Since phenol is a (very) weak acid, it might be possible to make a quantitative measurement by titration of phenol solution with a standard solution of alkali using phenolphthalein indicator.\nAnother possibility is to make use of the fact that phenol reacts readily with bromine to form tribromophenol. This would involve a rather complicated process:\n1. Add the phenol to a measured excess of bromine solution;\n2. Then add the solution with the excess bromine to potassium iodide solution (making sure that there is more than enough KI); this produces an equal amount of iodine to the excess bromine.\n3. Titrate the iodine with standard sodium thiosulphate solution (starch indicator).
464799
I assume that you have an equation such as A and B react together to give C. Work out the molar ratios of each, i.e. is it 1 equivalent of A reacted with 1 equivalent of B to give 1 equivalent of C?\nAssuming it is a 1:1:1 ratio, then look at the amounts you actually reacted - chances are that you did not use 1 mole of each of the reactants. Work out the molar quantities of each reactant. (mass used/molecular weight of compound)\n\nIf you used 0.5 moles of each, then you would get 0.5moles of product and just convert this to a mass.\n\nIf one of the reactants is in excess, e.g. 0.5 moles of A and 0.8moles of B was used, ignore B because as there is only 0.5 moles of A you would only make a maximum of 0.5 moles of C.\n\nHope this helps
659848
Boric Acid, white crystalline powder, formula H3BO3. Although boric acid is poorly soluble in water at room temperature (1 g dissolving in 18 g water), it dissolves readily in hot water (1 g dissolving in less than 4 g water) and in alcohol and glycerine. It is slightly volatile in steam. A significant amount of boric acid appears in natural steam vents in Tuscany, Italy, but free boric acid is not otherwise found in nature—the salts occur in many places. Boric acid can be easily prepared by treating borax with sulphuric acid. Boric acid in solution is only slightly acidic and acts as a nonirritating, slightly astringent antiseptic, mild enough to be used as an eyewash. Commercially, boric acid is used in glazing pottery, in fireproofing cloth, in electroplating baths and artificial gems, and in hardening steels.\n\n\nYou can absolitly use in treat of Vaginiosis that is good and for more info you can cantact me on ad786_alcatel@yahoo.com or 0093799990020.\n\nThanks \n\nRegards\n\nAssad.
762929
CH3CONH2 + Na+-OH ---->  CH3COO -Na+ +  :NH3\n\nThis is a amide hydrolysis reaction, similar to the hydrolysis of an ester. Hydroxide attacks carbonyl to give tetrahedral intermediate. Explulsion of an amide ion gives a carboxylic acid, which is deprotonated quickly to give the carboxylate ion and ammonia.