Assign the absolute stereochemistry for each of the following molecules drawn in their Fischer projection.
(d)

검증된 단계별 안내

Step 1: Identify the chiral center in the molecule. In the Fischer projection provided, the carbon atom at the intersection of the vertical and horizontal lines is the chiral center. This carbon is bonded to four different groups: CH₃, OH, H, and a triple bond (C≡C).

Step 2: Assign priorities to the substituents based on the Cahn-Ingold-Prelog (CIP) rules. The priority is determined by atomic number: (1) OH group (oxygen has the highest atomic number), (2) C≡C group (carbon in a triple bond has higher priority than CH₃), (3) CH₃ group, and (4) H (hydrogen has the lowest atomic number).

Step 3: Orient the molecule so that the lowest priority group (H) is pointing away from you. In a Fischer projection, the vertical bonds are considered to be pointing away from the viewer, while the horizontal bonds are pointing toward the viewer. Here, H is already on the vertical axis, so it is pointing away.

Step 4: Determine the order of the remaining groups (OH, C≡C, CH₃) in terms of priority. Trace the path from the highest priority (OH) to the second (C≡C) to the third (CH₃). If the path is clockwise, the configuration is R; if counterclockwise, it is S.

Step 5: Based on the direction of the path traced, assign the absolute stereochemistry (R or S) to the chiral center. Ensure that the lowest priority group (H) is correctly oriented before making the final determination.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Fischer Projections

Fischer projections are a two-dimensional representation of three-dimensional organic molecules, particularly useful for depicting stereochemistry in carbohydrates and amino acids. In these projections, vertical lines represent bonds that extend away from the viewer, while horizontal lines represent bonds that come towards the viewer. Understanding how to interpret Fischer projections is crucial for assigning stereochemistry accurately.

Absolute Stereochemistry

Absolute stereochemistry refers to the spatial arrangement of atoms in a molecule and is designated using the R/S system. This system is based on the Cahn-Ingold-Prelog priority rules, which assign priorities to substituents attached to a chiral center. By determining the configuration of the substituents around the chiral center, one can assign either an R (rectus) or S (sinister) designation, which is essential for understanding the molecule's 3D orientation.

Chirality

Chirality is a property of a molecule that has non-superimposable mirror images, much like left and right hands. A chiral molecule typically contains at least one carbon atom bonded to four different substituents, creating two distinct configurations. Recognizing chirality is fundamental in organic chemistry, as it influences the physical and chemical properties of compounds, including their biological activity.

Assign the absolute stereochemistry for each of the following molecules drawn in their Fischer projection.(d)