[decoys]

hi I need help for the following question that I got wrong. I thought that the the dial would react the fastest since it has 2 carbonyls to react with. In the question it says that aldehydes and ketones are less reactive than acid chlorides and anhydrides, so I ranked them accordingly, yet I still don't get why I got the question wrong. Should the acetic propionic anhydride come after the dial? 

[Archer]

Why do you think a dialdehyde would be more reactive than a mono-aldehyde?

[decoys]

Why do you think a dialdehyde would be more reactive than a mono-aldehyde?

wouldn't the reactivity increase with more carbonyl groups on a molecule since there are 2 carbonyl groups for a nucleophile to attack?

[Archer]

No, you still have an aldehyde (albeit on at each end of the molecule). The only way the reactivity of a C=O bond towards a nucleophile is altered is by stearic or electronic effects of neighboring groups.

I doubt that having two aldehydes so far apart isn't going to change either of these factors in any significant way.

[decoys]

No, you still have an aldehyde (albeit on at each end of the molecule). The only way the reactivity of a C=O bond towards a nucleophile is altered is by stearic or electronic effects of neighboring groups.

I doubt that having two aldehydes so far apart isn't going to change either of these factors in any significant way.

so a mono-aldehyde would react at the same speed as a di-aldehyde? :s

[Archer]

In your molecule any differences in reactivity relative to a mono-aldehyde would be negligible, the two carbonyls are separated by three σ bonds.

[orgopete]

Why do you think a dialdehyde would be more reactive than a mono-aldehyde?

Since a mono-aldehyde was not a choice, I presume this is meant to ask why butanedial should be more reactive than acetyl chloride.

[Archer]

Why do you think a dialdehyde would be more reactive than a mono-aldehyde?

Since a mono-aldehyde was not a choice, I presume this is meant to ask why butanedial should be more reactive than acetyl chloride.

No, I was pertaining to what if the question was worded differently to replace butanedial with,say, butanal how would this change the answer provided.

I thought that the the dial would react the fastest since it has 2 carbonyls to react with. In the question it says that aldehydes and ketones are less reactive than acid chlorides and anhydrides

[orgopete]

No, I was pertaining to what if the question was worded differently to replace butanedial with,say, butanal how would this change the answer provided.

Yes, but I noticed the poster had the dialdehyde reacting faster than acetyl chloride. If the poster missed that, why would you think they would be able to answer your hypothetical question?

[Archer]

Is it is fair to say that we may have interpreted why the poster made this error in different ways?

I get the impression that you think they misread the question.

I thought that they believed that a dialdehyde would have a greatly increased reactivity due to having twice as many functional groups on the molecule and therefore would be the most active of all. 

I thought (possibly incorrectly) that if they could see that there was no difference between the reactivity of an aldehyde and a dialdehyde of this type then logical progression would allow them to order their anwers correctly.

I apologise for any confusion that my responses may have caused.