[786mine]

how would I diffenciate with the following using simple chemical tests? Correct me where I am wrong

1. n-pentane and 1-pentene = i used Br as it would go color less in 1-pentene and not the other.

2. 1-pentene and 1-pentyne = i used AgNO3, it would give white ppt with 1-pentyne and not with 1-pentene.

3. 2-bromo-2-methylbutane and benzene = I wasn't too used about this. I used Br to as they do not have any effect on -ane compounds, therefore it would remain red in 2-bromo-2-methylbutane but would turn colorless in benzene. Correct?

4. 1-pentane and 2-bromo-2-methylbutane. totally lost here.

5. benzene and cyclopentadiene = Br? not sure. what will the results be with Br? and if someone can explain why?

6. 2-bromo-2-methylbutane and 1-bromopentane = AgNO3, white ppt on 1-bromopentane as its a terminal halide and no ppt in 2-bromo-2-methylbutane. Correct?

Thanks I appreciate

[786mine]

*Ignore me, I am impatient*, anyone?

[janne18]

Melting point?

[Garneck]

3. 2-bromo-2-methylbutane and benzene = I wasn't too used about this. I used Br to as they do not have any effect on -ane compounds, therefore it would remain red in 2-bromo-2-methylbutane but would turn colorless in benzene. Correct?

It wouldn't go colorless in benzene just like that. You need a catalysator - some Fe chips would work

4. 1-pentane and 2-bromo-2-methylbutane. totally lost here.

Add KOH in ethanol and then Br₂ to 2-bromo-2-methylbutane - it'll go colorless

5. benzene and cyclopentadiene = Br? not sure. what will the results be with Br? and if someone can explain why?

As I said, benzene needs a catalysator for bromine substitution. Cyclopentadiene would go colorless in Br₂ instantly

[786mine]

It wouldn't go colorless in benzene just like that. You need a catalysator - some Fe chips would workAdd KOH in ethanol and then Br₂ to 2-bromo-2-methylbutane - it'll go colorlessAs I said, benzene needs a catalysator for bromine substitution. Cyclopentadiene would go colorless in Br₂ instantly

Garneck, thanks for the help. Could you help me understand WHY, Br would react with 2-bromo-2-methylbutane and not 1-bromopentane instantly?

[dexangeles]

It wouldn't go colorless in benzene just like that. You need a catalysator - some Fe chips would workAdd KOH in ethanol and then Br₂ to 2-bromo-2-methylbutane - it'll go colorlessAs I said, benzene needs a catalysator for bromine substitution. Cyclopentadiene would go colorless in Br₂ instantly

he is trying to say..

with2-bromo-2methylbutane, the base will create elimination thus you'll have a double bond for reaction with Br₂

with benzene, you have to realize that benzene is aromatic thus very stable, it will not react via addition like in alkenes.  With Fe, it will react via Electrophilic Aromatic Substitution to forn bromobenzene

[Garneck]

Garneck, thanks for the help. Could you help me understand WHY, Br would react with 2-bromo-2-methylbutane and not 1-bromopentane instantly?

Because 2-bromo-2-methylbutane is a tertiary bromide, KOH causes it to form a alkene which reacts with bromine.