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The carbons of the chain are conventionally numbered from 1 to n, starting from the end which is closest to the carbonyl. If the carbonyl is at the very beginning of the chain (carbon 1), the monosaccharide is said to be an aldose, otherwise it is a ketose. These names can be combined with the chain length prefix, as in aldohexose or ...
The classic example is the conversion of glucose to arabinose as shown below. The reaction is named after the German chemist Alfred Wohl (1863–1939). The Wohl degradation. Let's say we have a kiliani-fischer synthesis, it basically removes the row of the C2 carbon, it shortens the carbon chain by one carbon.
Numbering of the chain. This is done by first numbering the chain in both directions (left to right and right to left), and then choosing the numbering which follows these rules, in order of precedence. Not every rule will apply to every compound, rules can be skipped if they do not apply. Has the lowest-numbered locant (or locants) for ...
The number of distinct stereoisomers with the same diagram is bounded by 2 c, where c is the total number of chiral carbons. The Fischer projection is a systematic way of drawing the skeletal formula of an acyclic monosaccharide so that the handedness of each chiral carbon is well specified.
A open-chain form of glucose makes up less than 0.02% of the glucose molecules in an aqueous solution at equilibrium. [58] The rest is one of two cyclic hemiacetal forms. In its open-chain form, the glucose molecule has an open (as opposed to cyclic) unbranched backbone of six carbon atoms, where C-1 is part of an aldehyde group H(C=O)−.
From Figure 1, oxy subunits are take precedence over acyclic carbon chain subunits. The preferred CRU is chosen as that with the lowest possible locant (s) for substituents . In the example, there is a bromo-substituted -CH 2 -CH 2 - subunit. 1-Bromoethane-1,2-diyl is chosen in preference to 2- bromoethane-1,2-diyl as the former has a lower ...
The carbon chain is then positioned vertically upward with all horizontal attachments pointing toward the viewer. [2] Finally, attachments to main chain carbons that face away from the viewer are placed in the vertical position of the Fischer projection, and those that face toward the viewer are placed in the horizontal position of the Fischer ...
Cations and anions are also typically discrete and can be depicted unambiguously. For simple structures, say <10 atoms, it is helpful to depict all atoms explicitly. For more complex molecules, most hydrogen atoms attached to carbon are omitted, and carbon atoms are represented by vertices. For ease of readability, sans-serif fonts are ...