3,28-Diacet-oxy-29-bromo-betulin
Summary
This study details the molecular structure of a brominated organic compound, C(34)H(53)BrO(4). The research reveals specific ring conformations and intermolecular interactions within its crystal structure.
Area of Science:
- Organic Chemistry
- Crystallography
- Molecular Structure
Background:
- Understanding the three-dimensional arrangement of atoms in organic molecules is crucial for predicting their properties and reactivity.
- Crystal structure analysis provides detailed insights into molecular conformations and intermolecular forces.
Purpose of the Study:
- To elucidate the precise molecular structure and conformation of the title compound, C(34)H(53)BrO(4).
- To investigate the intermolecular interactions governing the crystal packing of this molecule.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the molecular and crystal structure.
- Conformational analysis of the cyclic systems within the molecule was performed.
Main Results:
- The molecule C(34)H(53)BrO(4) features cyclohexane rings adopting chair conformations and a cyclopentane ring in an envelope conformation.
- Analysis revealed the presence of weak intermolecular C-H⋯O hydrogen bonds.
- These interactions organize the molecules into corrugated sheets within the crystal lattice, parallel to the ab plane.
Conclusions:
- The study provides a detailed structural characterization of C(34)H(53)BrO(4).
- The identified conformations and hydrogen bonding patterns are key to understanding the solid-state behavior of this compound.
Related Concept Videos
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Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Electrophilic 1,2- and 1,4-Addition of HX to 1,3-Butadiene
The electrophilic addition of hydrogen halides such as HBr to alkenes and nonconjugated dienes gives a single product as per Markovnikov’s rule.
Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
π Molecular Orbitals of 1,3-Butadiene
Conjugated dienes have lower heats of hydrogenation than cumulated and isolated dienes, making them more stable. The enhanced stabilization of conjugated systems can be understood from their π molecular orbitals.
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
Degree of Unsaturation
The degree of unsaturation (U), or index of hydrogen deficiency (IHD), is defined as the difference in the number of pairs of hydrogen atoms between the compound and the acyclic alkane with the same number of carbon atoms. Each double bond or ring costs two hydrogen atoms compared to a saturated analog and results in one degree of unsaturation.
The degree of unsaturation for hydrocarbons is U = (2C + 2 − H) / 2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
For...
The degree of unsaturation for hydrocarbons is U = (2C + 2 − H) / 2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
For...


