When distilling cyclohexanol to get cyclohexene, why do you shake saturated sodium chloride solution with the crude alkene? Does this help to remove impurities in some way? I can't find the answer anywhere! Also, why is anhydrous calcium chloride added to the cyclohexene? Is it to remove excess water from the alkene? Any help would be much appreciated!!
2006-06-13 09:20:01 · 7 answers · asked by Showaddywaddy 5 in Science & Mathematics ➔ Chemistry
Saturated sodium chloride solution is highly polar, and will help to drive large amounts of water and other non-organic materials out of the organic solution (water will have a greater affinity for the salt solution, and will also attempt to dilute the salt). The last traces of water will be grabbed by the anhydrous calcium chloride (though magnesium sulfate or sodium sulfate work better, as they are usually more granular).
2006-06-13 10:27:41 · answer #1 · answered by TheOnlyBeldin 7 · 3⤊ 1⤋
Okay. The serious answers to date are right, but they haven't told you what this has to do with distillation. If you dont' mind I'll take it right from the beginning
The reaction of cyclohexanol to make cyclohexene is acid catalyzed dehydration, so there is always some water with the products, from the acid and from the reaction products.
Shaking it with saturated NaCl takes out most of the water, and the anhydrous calcium chloride mops up whatever is left.
The reason you need to take out the water is that both cyclohexanol and cyclohexene form azeotropes with water. If you are trying to isolate cyclohexene (the usual), the best you will get with distillation is the azeotropic mix of water and cyclohexene, you will not get pure cyclohexene.
If you want to distill off pure cyclohexene, you need to take out the water first. Thus all the drying steps above.
(I assume you know what an azeotrope is ; if not, it is a mixture which has the same composition in the vapour and liquid phases. That means that distiilation can't be used to separate them)
2006-06-14 12:01:27 · answer #2 · answered by The_Otter 3 · 1⤊ 0⤋
Not sure on the first part, but the reason for annhydrous Calcium Chloride is to remove the excess water. I think the answer to the first part is to begin the conversion process of the cyclohexanol to the cyclohexene by forming a cyclohexoxide. I could be wrong on that one though.
2006-06-13 16:27:05 · answer #3 · answered by Darryl E 2 · 0⤊ 0⤋
Addition of brine helps to remove water soluble impurities. In the reaction you describe the alcohol is much more water soluble than the olefin (though they're still not as soluble as say ethanol or lower homogolates). Anhydrous calcium chloride is as you say typically used as a drying agent to remove the last dredges of water from the solution.
2006-06-13 16:31:04 · answer #4 · answered by Stephan B 5 · 0⤊ 0⤋
i don't know but just wanted the 2 points
thanks
2006-06-13 16:38:01 · answer #5 · answered by last 2 · 0⤊ 0⤋
i cant even pronounce them words let alone give u an answer...u must be real smart or makeing drugs...lol cheers
2006-06-13 16:25:45 · answer #6 · answered by jjohnmichael4u 2 · 0⤊ 0⤋
who cares braniac? you are a wee jobby pick me for best answer and i will let you see my dong later on!!!
2006-06-13 16:58:42 · answer #7 · answered by jonnybeanos 2 · 0⤊ 0⤋