Examville
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Fischer Projections The figures depict the structure of D and L- Glyceraldehyde shown in Fischer projections. It was devised by Hermann Emil Fischer in 1891. The three dimensional view of a compound with an asymmetrical carbon can be easily drawn in two dimensions using this Fischer projection. A long vertical line in this represents the maximum lengthened continuous carbon chain. The carbon chain is oriented in such a way that the C1 carbon is at the top. All along the length of this vertical line, we can intersect with a series of horizontal lines to represent atoms or atom groups their ends. The point where the horizontal lines are intersecting the vertical line is considered as a carbon atom. Comparing the three dimensional view of molecules, the atoms or atom groups in Fischer projections which are shown at the ends of horizontal lines along the extension of the vertical line, has to be projected in front of the plane. The atoms which are along the vertical line have to be projected behind the plane.
The atoms behind the plane are shown by dotted wedges and the atoms in front of the plane are denoted by joined wedges. The joined line represents the atom within the plane.
The simplest sugars of glucose and fructose tend to cyclize their open chain structure and form rings. These cyclic structures can be represented as follows
In D – glucose, the six membered ring of glucopyranose results as a formation of the hemiacetal group between the aldehyde group in 1st carbon and the hydroxyl group of 5th carbon present in the open chain structure. This formation of intramolecular hemiacetal is observed in aldoses.
In ketoses, there is a formation of intramolecular hemiketal. In the open chain structure of a ketohexose like D – Fructose, the keto group in 2nd carbon reacts with the hydroxyl group of 5th carbon resulting in the five membered cyclic ring of fructofuranose. Here, there is a possibility of formation of six membered cyclic ring also, called as fructopyranose resulting from reaction between C-2 keto group and C-6 hydroxyl group.
The atoms behind the plane are shown by dotted wedges and the atoms in front of the plane are denoted by joined wedges. The joined line represents the atom within the plane.
The simplest sugars of glucose and fructose tend to cyclize their open chain structure and form rings. These cyclic structures can be represented as follows
In D – glucose, the six membered ring of glucopyranose results as a formation of the hemiacetal group between the aldehyde group in 1st carbon and the hydroxyl group of 5th carbon present in the open chain structure. This formation of intramolecular hemiacetal is observed in aldoses.
In ketoses, there is a formation of intramolecular hemiketal. In the open chain structure of a ketohexose like D – Fructose, the keto group in 2nd carbon reacts with the hydroxyl group of 5th carbon resulting in the five membered cyclic ring of fructofuranose. Here, there is a possibility of formation of six membered cyclic ring also, called as fructopyranose resulting from reaction between C-2 keto group and C-6 hydroxyl group.
