orgo people....i got couple questions

[WayneSU]

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K got a couple orgo questions

1--for an ether with one mole of HCl....how do u no which half of the ether will become an alcohol and which half is goin to become an alkyl halide.

ex..if u have (CH3)2CHOCH3 + 1mol HCl.....would u get a seconday or primay alcohol and why

2-- k as i understand it..double bonds increase both melting point and boiling point, correct? k then why is it with fatty acids, the more unsaturated it is, the more fluid and the lesser the Melting point? since it has more double bonds, wouldnt it have a higher melting point than a saturated fatty acid

 

[Maygyver]

K got a couple orgo questions

1--for an ether with one mole of HCl....how do u no which half of the ether will become an alcohol and which half is goin to become an alkyl halide.

ex..if u have (CH3)2CHOCH3 + 1mol HCl.....would u get a seconday or primay alcohol and why

2-- k as i understand it..double bonds increase both melting point and boiling point, correct? k then why is it with fatty acids, the more unsaturated it is, the more fluid and the lesser the Melting point? since it has more double bonds, wouldnt it have a higher melting point than a saturated fatty acid

The second one is true because unsaturated fats have kinks in them which do not allow as close of packing as saturated fats so they exist as liquids.

 

[keliao]

(CH3)2CHOCH3 ??..i drew it out and it came out weird. ..........????? did you mean a Carbon bonded to (OH) and (CH3)3 ???

 

[Maygyver]

(CH3)2CHOCH3 ??..i drew it out and it came out weird. ..........????? did you mean a Carbon bonded to (OH) and (CH3)3 ???

No, it's an ether. C bonded to OCH3, 2 CH3s and an H.

 

[IWantH2O]

The second one is true because unsaturated fats have kinks in them which do not allow as close of packing as saturated fats so they exist as liquids.

k now im confused...but its still true that double bonds raise the melting point..right

and im really curoius bout the second question now..anybodys nos

 

[keliao]

if you have CH3)2CHOCH3 + 1mol HCl then it'll b

CH3CL + CH3-CH=CH2


i can't think of a rxn from ether to alcohol

 

[Sea of ASH]

K got a couple orgo questions

1--for an ether with one mole of HCl....how do u no which half of the ether will become an alcohol and which half is goin to become an alkyl halide.

ex..if u have (CH3)2CHOCH3 + 1mol HCl.....would u get a seconday or primay alcohol and why

2-- k as i understand it..double bonds increase both melting point and boiling point, correct? k then why is it with fatty acids, the more unsaturated it is, the more fluid and the lesser the Melting point? since it has more double bonds, wouldnt it have a higher melting point than a saturated fatty acid

1- it depends which side is a better leaving group.... i.e. which one wants to carry the negative charge

2- BP depends mostly on intermolecular forces (ionice, h-bonds etc)
MP (for alkenes) depends on symmetry... the more symmtrical the higher the MP..... BUT in the case of fatty acids, Maygyver nailed it on the head 👍

 

[plaier]

K got a couple orgo questions

1--for an ether with one mole of HCl....how do u no which half of the ether will become an alcohol and which half is goin to become an alkyl halide.

ex..if u have (CH3)2CHOCH3 + 1mol HCl.....would u get a seconday or primay alcohol and why

2-- k as i understand it..double bonds increase both melting point and boiling point, correct? k then why is it with fatty acids, the more unsaturated it is, the more fluid and the lesser the Melting point? since it has more double bonds, wouldnt it have a higher melting point than a saturated fatty acid

1- At first, lone pair of Oxygen in ether get protonated by H. then its either goes with SN2 and SN1, but this ether only contain secondary and primary alkyl. SN2 will favor in that primary alkyl group. the Bromide ion will attack methyl (not isopropyl) which is much less hindered. you get a secondary alcohol and primary bromide.

another example, If you have (CH3)3C-O-CH3. then it will go under SN1 to make tertiary carbocation. Therefore, you will get primary alcohol and tertiary bromide.

So use your knowledge of SN1 and SN2 substitution, then it is easy



2- Fatty acids with unsaturation have wierd shape while a saturated fatty acid has straight Hydrocarbon chain. so saturated fatty acid win.

furthermore, compare Neopentanol isopentanol and n-pentanol.

Neopentanol: mp:+52 bp:+113
isopentanol: mp:-117 bp:+132
n-pentanol: mp:-79 bp:+138

boiling point follows with more branched one with lower bp (easy)

but melting points look wierd, isnt it?
2 methyl branched Neopentanol has higest mp, then no methyl branched n-pentanol is much lower mp, and 1 methyl branched isopentanol has the lowest.(they are all isomers)
there is different rule on mp.

Carnelley's Rule established in 1882 by Thomas Carnelley, states that high molecular symmetry is associated with high melting point.

Neopentanol has perfect symmetry with tetrahedral shapes, like neopentane.

You have to see molecular symmetry in 3D picture for melting points of organic compounds while you see number of branchs for boiling points.

3rules for mp!!
1)intermolecular forces such as hydrogen bonds raise MP(acetic acid>ethanol>dimethyl ether>ethane)
2) high molecular symmetry associated with high melting point.(neopentane>n-pentane>isopentane)
3)heavier molecules have higher mp. (hexane>pentane>butane)

 

[doc3232]

I was dreaming about your first question last night...I think due to stability.
If methanol and (CH3)2CHBr forms. Basically, I think because CH3O- is more stable than the other one. and the two methyls can stabilize the cation that forms.