Question

Give L-fucose ("Chemical Connections: A, B, AB, and O Blood Group Substances") a name incorporating the prefix deoxy- that shows its relationship to galactose.

Short answer

Answer: 6-deoxy-L-galactose

Step-by-step solution

Understand the structure of L-fucose and galactose

L-fucose and galactose are both monosaccharides, which means they are the simplest form of sugar and cannot be hydrolyzed into smaller carbohydrates. Their chemical structures can be represented using the Fischer projection or the Haworth projection. In this case, we will use the Fischer projection for simplicity. L-fucose has the structure: HOCH2(CHOH)3C=O Galactose has the structure: HOCH2(CHOH)4CHO

Identify the difference between the two structures

By comparing the two structures, we can see that they are very similar, but with a crucial difference: whereas galactose has a hydroxyl group (OH) on the C6 carbon atom (the last carbon atom on the right), L-fucose has a hydrogen atom instead. This is the reason why L-fucose can be considered a deoxy sugar and why it deserves the prefix deoxy- in its alternative name.

Determine the relationship between L-fucose and galactose

L-fucose and galactose are both hexoses, which means they have six carbon atoms in their structure. Moreover, they are also both aldoses, meaning they have an aldehyde functional group (C=O) at the end of their chain. The fact that they are both aldohexoses, coupled with their chemical structures' similarity, indicates that L-fucose is a deoxy derivative of galactose.

Formulate the alternative name for L-fucose

Considering that L-fucose is a deoxy derivative of galactose, we can use the prefix "deoxy-" in its alternative name. To indicate the relationship between them, we will use the term "deoxygalactose." Therefore, the alternative name for L-fucose that shows its relationship to galactose is "6-deoxy-L-galactose." In conclusion, L-fucose can be alternatively called 6-deoxy-L-galactose.