Organic Chemistry question

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king_23
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Organic Chemistry question

Post by king_23 » Tue Jun 27, 2006 1:52 am

1. In organic chemistry, naming alkanes and alkenes, there's something I'd like to be made clear. For example, with alkanes, lets say its butene with a ring structure, it would be named cyclobutene. With alkenes, in a butene with ring structure and a single double bond, it is also named cyclobutene. If asked to draw cyclobutene how would you know which to draw? The one with or the one without the double bond.

2. Naming alkanes with ring structures and lets say there's a methyl branch, is it 1-Methylcyclobutene or would it just be Methylcyclobutene where the former one is used if it is an alekene?

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mith
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Post by mith » Tue Jun 27, 2006 3:02 am

wouldn't butene be only alkenes and not alkanes??
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Post by herb386 » Tue Jun 27, 2006 7:54 am

I think it is called butane for alkanes (cyclobutane for the ring structure) and butene for alkenes (cyclobutene for the ring structure).

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Post by oppox » Tue Jun 27, 2006 2:47 pm

1. the one with one double bond is called cyclobutene (alkene) the one without is called cyclobutane (alkane).

2. the name is, for an example 1-methyl-1-cyclobutene, if the methyl is on the same carbone as the db, and 1-methyl-2-cyclobutene if its not.

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Post by majik1213 » Fri Jun 30, 2006 5:10 pm

Let's go through what you say step by step:

1. In organic chemistry, naming alkanes and alkenes, there's something I'd like to be made clear. For example, with alkanes, lets say it's butene with a ring structure, it would be named cyclobutene.

^What you just said is incorrect. What should be written instead is, "For example, with alkanes, let's say it's BUTANE with a ring structure, it would be named CYCLOBUTANE."


With alkenes, in a butene with ring structure and a single double bond, it is also named cyclobutene. If asked to draw cyclobutene how would you know which to draw? The one with or the one without the double bond.

^cyclobutene would be the one with the double bond. Cyclobutane, in contrast to cyclobutene, would be the one without the double bond.
^You can get away with saying cyclobutene because 1-cyclobutene = 2-cyclobutene = 3-cyclobutene = 4-cyclobutene; however, you cannot simply say butene; you must be specific to with respect to the location of the double bond by saying 1-butene. Indeed, 1-butene does NOT equal 2-butene, which does NOT equal 3-butene (although 1-butene = 4-butene, but I hope you see my point). Why people can't just let alkene be synonymous to 1-alkene is beyond me. In older literature, one would say n-butene, where n stands for "normal," but that method for naming organic compounds is obsolescent (according to my professor).

2. Naming alkanes with ring structures and lets say there's a methyl branch, is it 1-Methylcyclobutene or would it just be Methylcyclobutene where the former one is used if it is an alekene?

^Again, you would say, "is it 1-methylcyclobutANE or would it just be methylcyclobutANE?" Here, because 1-methylcyclobutane = 2-methylcyclobutane = 3-methylcyclobutane = 4-methylcyclobutane, it suffices to say simply methylcyclobutane. And, although I'm not certain, I feel as though any monosubstituted cycloalkane can be named without the numerical prefix. You will never be wrong by saying 1-methylcyclobutane, by the way, although doing so would be heterodox.

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