Bulky Groups
Bulky Groups - Related Videos
08:12
Pressure Transducer: Calibration Using a Pitot-static Tube
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2023
Source: Shreyas Narsipur, Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC Fluid pressure is an important flow characteristic that is required to determine the aerodynamics of a system. One of the oldest and still existing pressure measurement systems is the manometer due to its accuracy and simplicity of operation. The manometer is generally a U-shaped glass tube that is partially filled with liquid, as shown in Figure 1. The U-tube manometer requires no...
11:23
Lensless Fluorescent Microscopy on a Chip
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Cited by 8 •
2011
A lensless on-chip fluorescent microscopy platform is demonstrated that can image fluorescent objects over an ultra-wide field-of-view of e.g., >0.6-8 cm2 with <4μm resolution using a compressive sampling based decoding algorithm. Such a compact and wide-field fluorescent on-chip imaging modality could be valuable for high-throughput cytometry, rare-cell research and microarray-analysis.
06:52
Ozonolysis of Alkenes
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2023
Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate an example of an ozonolysis reaction to synthesize vanillin from isoeugenol (Figure 1). Ozonolysis of alkenes, an oxidation reaction between ozone and an alkene, is a common method to prepare aldehydes, ketones, and carboxylic acids. This experiment also demonstrates the use of an ozone generator and a low temperature (−78 °C) reaction. Figure 1. Diagram showing...
08:54
Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals
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Cited by 3 •
2016
A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.
08:34
Field-Deployable Lens-Free Imaging Platform for Rapid Label-Free Analysis of Natural Killer Cell Activation
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Cited by 1 •
2025
This protocol describes a label-free method for the rapid single-cell analysis of natural killer (NK) cell count and activity using lens-free shadow imaging technology. This method quantifies morphological changes in individual NK cells by computerized analysis of their diffraction patterns.
FAQs
Steric hindrance creates repulsive interactions when atoms or substituents approach a crowded reaction center. Reagents therefore tend to favor pathways that reduce these close contacts, often approaching from the less congested side of a molecule. This preference can change which bond forms or where a reaction occurs, allowing chemists to influence regioselectivity and stereoselectivity through spatial design.
Crowded substituents can make some arrangements less favorable because they increase repulsive interactions between nearby parts of a molecule. The molecule may respond through altered bond angles or by favoring a different conformation, meaning one three-dimensional arrangement becomes more accessible than another. These changes matter because conformation affects which reaction pathways or molecular interactions are available.
Bulky ligands can shield a metal center by occupying space around it, limiting access by other molecules or reactive groups. This protection may prevent unwanted reactions while also altering catalyst activity. In coordination chemistry, the ligand's spatial demands therefore become a design variable: changing crowding near the metal can influence how readily the center participates in a catalytic process.
Chemists consider how the substituent will distribute crowding near the reaction center and which approach it is likely to block. Groups such as tert-butyl or highly substituted aryl groups can be introduced when spatial control is needed. Their placement can favor a less crowded reaction pathway, helping direct regioselectivity, stereoselectivity, or the stability of a reactive intermediate.
In organic synthesis, bulky groups are useful when competing reaction pathways differ in spatial congestion. By making one approach more difficult than another, they can guide reagent attack and influence the location or three-dimensional arrangement of a product. They can also affect reactive-intermediate stability, giving chemists a way to manage selectivity through molecular shape rather than relying only on reagent identity.
Steric design extends beyond individual organic reactions. Around a metal center, bulky ligands can regulate accessibility and catalyst behavior, while in molecular materials research, substituent size can help control molecular shape and interactions. Across these areas, the central practical outcome is the same: deliberate spatial arrangement can limit unwanted contacts and tune the behavior of a chemical system.