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A Newman projection is a drawing that helps visualize the 3-dimensional structure of a molecule. [1] This projection most commonly sights down a carbon-carbon bond ...
The example below is looking down the C2 and C3 bond. Below is the sawhorse and Newman representation of butane in an eclipsed conformation with the two CH 3 groups (C1 and C4) at a 0-degree angle from one another (left). If the front is rotated 60° clockwise, the butane molecule is now in a staggered conformation (right).
In the Newman projection, a circle is used to represent a plane perpendicular to the bond, distinguishing the substituents on the front carbon from the substituents on the back carbon. In the sawhorse projection, the front carbon is usually on the left and is always slightly lower. Sometimes, an arrow is used to indicate the front carbon.
Above: Newman projection; below: depiction of spatial orientation. In chemistry, rotamers are chemical species that differ from one another primarily due to rotations about one or more single bonds. Various arrangements of atoms in a molecule that differ by rotation about single bonds can also be referred to as different conformations ...
Figure 5 shows 2-chloro-2,3-dimethylbutane in a sawhorse projection with chlorine and a hydrogen anti-periplanar to each other. Syn-periplanar or synperiplanar is similar to anti-periplanar. In the syn-periplanar conformer, the A and D are on the same side of the plane of the bond, with the dihedral angle of A−B and C−D between +30° and ...
In stereochemistry, a torsion angle is defined as a particular example of a dihedral angle, describing the geometric relation of two parts of a molecule joined by a chemical bond. [4] [5] Every set of three non-colinear atoms of a molecule defines a half-plane. As explained above, when two such half-planes intersect (i.e., a set of four ...
Alternately, all four groups can be ranked by Cahn–Ingold–Prelog priority rules, with overall priority given to the two groups on the "front" atom of the Newman projection. The two configurations determined in this way are termed R a and S a , in analogy to the traditional R / S for a traditional tetrahedral stereocenter.
The Cram's rule of asymmetric induction named after Donald J. Cram states In certain non-catalytic reactions that diastereomer will predominate, which could be formed by the approach of the entering group from the least hindered side when the rotational conformation of the C-C bond is such that the double bond is flanked by the two least bulky groups attached to the adjacent asymmetric center. [3]