Answer to Question #103686 in Organic Chemistry for kylie

Question

What is the name given for the different arrangement of atoms in space at a stereogenic center, such as a carbon atom that bears four different atoms or groups?

(1) resonance (2) configurations (3) conformations (4) tortional isomers

Answer 1

The correct answer is (2) configurations (R- or S-configuration).

Consider the first picture: a curved arrow is drawn from the highest priority (1) substituent to the lowest priority (4) substituent. If the arrow points in a counterclockwise direction (left when leaving the 12 o' clock position), the configuration at stereocenter is considered S ("Sinister" → Latin= "left"). If, however, the arrow points clockwise,(Right when leaving the 12 o' clock position) then the stereocenter is labeled R ("Rectus" → Latin= "right"). The R or S is then added as a prefix, in parenthesis, to the name of the enantiomer of interest.

References:

1.         Chemistry: LibreTexts [Electronic resource] : supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. - Mode of access: https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Chirality/Absolute_Configuration%2C_R-S_Sequence_Rules. – Date of access: 26.02.2020.