Strain Baeyer

Baeyer strain theory (Section 3 4) Incorrect nineteenth century theory that considered the nngs of cycloalkanes to be planar and assessed their stabilities according to how much the angles of a corresponding regular polygon devi ated from the tetrahedral value of 109 5°... 

The Baeyer strain theory is useful to us in identifying angle strain as a destabilizing effect. Its fundfflnental flaw is its assumption that the rings of cycloalkanes are planar-. With the exception of cyclopropane, cycloalkanes are nonplanar. Sections 3.5-3.13 describe the shapes of cycloalkanes. We ll begin with cyclopropane. 

Backbone (protein), 1028 Backside displacement. reaction and.363-364 von Baeyer, Adolf, 113 Baeyer strain theory, 113-114 Bakelile, structure of, 1218 Banana, esters in, 808 Barton, Derek, H. R., 389 Basal metabolic rate, 1169 Basal metabolism. 1169-1170 Base, Bronsted-Lowry, 49 Lewis, 57, 59-60 organic, 56-57 strengths of, 50-52 Base pair (DNA), 1103-1105 electrostatic potential maps of. 

Baeyer strain theory org chem The theory that the relative stability of penta- and hexamethylene ring compounds is caused by a propitious bond angle between carbons and a lack of bond strain. ba-or stran, the-3-re baking soda See sodium bicarbonate. bak-ir, sod-s ... 

Introduction Baeyer Strain Theory The Origin and T3fpes of Strain. 718... 

Note Bond path angles / are used for bent bonds. According to Hooke s law, the Baeyer strain energy is 41.3 kcalmoT1 anharmonicity effects lead to another 5 kcal moT1 ... 

It is of historical interest to note that the Baeyer strain theory with its planar rings predicts only one form of decalin with the ring-junction hydrogens on the same side of the molecule (Figure 12-23). The Sachse-Mohr concept of puckered strain-free rings allows for two isomers. In fact, Mohr predicted that the two isomers of decalin should exist before W. Hiickel (1925) succeeded in preparing them. Both isomers occur in petroleum. 

The smaller bond angles prevent normal overlap along the intemuclear axis (dotted line). Overlap occurs outside the intemuclear axis and a bent bond is formed (also referred to as a r bond). The r bond is weaker than a a bond due to nonoptimal overlap and thus is of higher energy. This type of strain is termed angle strain (sometimes called Baeyer strain). It comes about because normal bond angles are not possible and thus nonoptimal overlap results. Angle strain... 

Comparison of the heats of combustion of cycloalkanes (Table 9.1) shows that cyclopropane, cyclobutane, and cyclononane yield more energy per methylene group than the other cycloalkanes. This can be attributed to strain resulting from bond-angle distortion (Baeyer strain), eclipsed conformations (Pitzer strain), and trans-annular, repulsive van der Waals interactions. Common (five- and six-membered) rings and large (more than twelve-membered) rings have little or no strain. This... 

If a cycloalkane requires bond angles other than 109.5°, the orbitals of its carbon-carbon bonds cannot achieve optimum overlap, and the cycloalkane must have some angle strain (sometimes called Baeyer strain) associated with it. Figure 3-14 shows that a planar cyclobutane, with 90° bond angles, is expected to have significant angle strain. 

Internal strain in cyclic systems 93,95) incorporates angle strain (Baeyer strain), torsional strain (Pitzer strain) and transannular strain. In the case of nitrogen inversion, large effects are expected to arise from angle strainb>, the nature of the cyclic system imposing a value of the angle 0... 

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