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I came across this on Wikipedia:

Many disaccharides, like cellobiose, lactose and maltose, also have a reducing form, as one of the two units may have an open-chain form with an aldehyde group. However, sucrose and trehalose, in which the anomeric carbons of the two units are linked together, are nonreducing disaccharides since neither of the rings is capable of opening.

https://en.wikipedia.org/wiki/Reducing_sugar#Aldoses_and_ketoses

I took the following Haworth projection of sucrose for comparision.

That's all fine and dandy, but the thing is, I can't seem to find any source that (explicitly) explains why this whole 'ring-opening' business even happens in disaccharides like maltose, but not in sucrose.

The Wikiedia article probably implies that this has to do with the fact that both the monomers of sucrose are bound through their anomeric carbons, which is not the case with maltose. A quick look at the structures of maltose and sucrose confirms this, however; pardon me if I'm being dense here (I can't seem to think straight today...don't ask me why, I'm clueless myself), but I don't see how that piece of information helps.

Can anyone explain this disrepancy?

I came across this on Wikipedia:

Many disaccharides, like cellobiose, lactose and maltose, also have a reducing form, as one of the two units may have an open-chain form with an aldehyde group. However, sucrose and trehalose, in which the anomeric carbons of the two units are linked together, are nonreducing disaccharides since neither of the rings is capable of opening.

I took the following Haworth projection of sucrose for comparison-

That's all fine and dandy, but the thing is, I can't seem to find any source that (explicitly) explains why this whole 'ring-opening' business even happens in disaccharides like maltose, but not in sucrose.

The Wikipedia article probably implies that this has to do with the fact that both the monomers of sucrose are bound through their anomeric carbons, which is not the case with maltose. A quick look at the structures of maltose and sucrose confirms this, however; pardon me if I'm being dense here, but I don't see how that piece of information helps.

Can anyone explain this discrepancy?

I came across this on Wikipedia:

Many disaccharides, like cellobiose, lactose and maltose, also have a reducing form, as one of the two units may have an open-chain form with an aldehyde group. However, sucrose and trehalose, in which the anomeric carbons of the two units are linked together, are nonreducing disaccharides since neither of the rings is capable of opening.

https://en.wikipedia.org/wiki/Reducing_sugar#Aldoses_and_ketoses

I took the following Haworth projection of sucrose for comparision.

That's all fine and dandy, but the thing is, I can't seem to find any source that (explicitly) explains why this whole 'ring-opening' business even happens in disaccharides like maltose, but not in sucrose.

The Wikiedia article probably implies that this has to do with the fact that both the monomers of sucrose are bound through their anomeric carbons, which is not the case with maltose. A quick look at the structures of maltose and sucrose confirms this, however; pardon me if I'm being dense here (I can't seem to think straight today...don't ask me why, I'm clueless myself), but I don't see how that piece of information helps.

Any ideas people?

I came across this on Wikipedia:

Many disaccharides, like cellobiose, lactose and maltose, also have a reducing form, as one of the two units may have an open-chain form with an aldehyde group. However, sucrose and trehalose, in which the anomeric carbons of the two units are linked together, are nonreducing disaccharides since neither of the rings is capable of opening.

https://en.wikipedia.org/wiki/Reducing_sugar#Aldoses_and_ketoses

I took the following Haworth projection of sucrose for comparision.

That's all fine and dandy, but the thing is, I can't seem to find any source that (explicitly) explains why this whole 'ring-opening' business even happens in disaccharides like maltose, but not in sucrose.

The Wikiedia article probably implies that this has to do with the fact that both the monomers of sucrose are bound through their anomeric carbons, which is not the case with maltose. A quick look at the structures of maltose and sucrose confirms this, however; pardon me if I'm being dense here (I can't seem to think straight today...don't ask me why, I'm clueless myself), but I don't see how that piece of information helps.

Can anyone explain this disrepancy?