✔ 最佳答案
1.
What? Of course there could be difference in physical and chemical properties between isomers!
In aldehyde group -CH(=O) there's oxygen atom that can donate lone-pair to lone-pair acceptor;
in hydroxy group -OH there's hydrogen attached to highly-electronegative atom (O), that can accept lone-pair from lone-pair donor.
Thus, with these two groups Hydrogen-bond can be formed.
In 2-hydrobenzaldehyde, the hydroxy group and aldehyde group are close to each other, which makes formation of INTRA-molecular H-bond very feasible. This reduces the extent of formation of INTER-molecular H-bond.
In contrast, in 4-hydroxybenzaldehyde, the two groups in same molecule are far away from each other. Intra-molecular H-bond is not feasible, so it'll give more inter-molecular H-bond.
2.
Are you sure?
from what I see from Wikipedia, decane has higher b.p. than 2,2,3,3-tetramethylbutane. Go and check it.
To explain this, compare their:
- molecular size
- length of main carbon chain, hence shape of the molecule
- strength of instantaneous dipole etc.
2012-08-25 23:01:41 補充：
Don't worry, quite often exercise books include incorrect information.
Just in case Wikipedia was wrong, I checked CRC Handbook of Chemistry and Physics, 79th ed. ; and I am correct.
2012-08-25 23:07:41 補充：
But you may notice that decane has lower Melting Point than 2,2,3,3-tetramethylbutane.
Think about packing etc.
