Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

SN2 Reaction: Stereochemistry02:23

SN2 Reaction: Stereochemistry

In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
SN2 Reaction: Mechanism02:27

SN2 Reaction: Mechanism

The kinetic studies of SN2 reactions suggest an essential feature of its mechanism: it is a single-step process without intermediates. Here, both the nucleophile and the substrate participate in the rate-determining step.
The presence of the more electronegative halogen in the substrate creates a polarized carbon-halide bond. The halide pulls the electron cloud generating an electrophilic center at the carbon atom. Thus, the carbon atom carries a partial positive charge while the halide has a...
SN2 Reaction: Transition State02:26

SN2 Reaction: Transition State

An SN2 reaction of an alkyl halide is a single-step process in which bond formation between the nucleophile and the substrate and bond breaking between the substrate and the halide occurs simultaneously through a transition state without forming an intermediate.
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
E2 Reaction: Kinetics and Mechanism02:45

E2 Reaction: Kinetics and Mechanism

SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Chih Tu: a pioneer of Xinjiang's agricultural science.

Protein & cell·2014
Same author

National trends and disparities in cervical cancer screening among commercially insured Women, 2001-2010.

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology·2014
Same author

Persistent medication affordability problems among disabled Medicare beneficiaries after Part D, 2006-2011.

Medical care·2014
Same author

Characterizing topological patterns in amnestic mild cognitive impairment by quantitative water diffusivity.

Journal of Alzheimer's disease : JAD·2014
Same author

Access to affordable medicines after health reform: evidence from two cross-sectional surveys in Shaanxi Province, western China.

The Lancet. Global health·2014
Same author

Increased acyl ghrelin but decreased total ghrelin and unacyl ghrelin in Chinese Han people with impaired fasting glucose combined with impaired glucose tolerance.

Peptides·2014

Related Experiment Video

Updated: Jul 16, 2026

Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations
13:09

Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations

Published on: January 4, 2018

[Research on substrate transformation mechanism in A2/O process].

Wei-Feng Xu1, Yin-Guang Chen, Guo-Wei Gu

  • 1State Key Laboratory of Pollution Control and Resource Reuse, Tongli University, Shanghai 200092, China. steve78107@163.com

Huan Jing Ke Xue= Huanjing Kexue
|March 1, 2007
PubMed
Summary

Nitrate presence in anaerobic conditions reduces phosphorus-accumulating organisms (PAOs) efficiency and polyhydroxyalkanoates (PHAs) synthesis. However, nitrate does not impact overall phosphorus uptake capacity.

More Related Videos

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
09:37

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

Published on: October 18, 2019

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
07:36

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

Published on: November 9, 2019

Related Experiment Videos

Last Updated: Jul 16, 2026

Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations
13:09

Utilization of Stop-flow Micro-tubing Reactors for the Development of Organic Transformations

Published on: January 4, 2018

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
09:37

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

Published on: October 18, 2019

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
07:36

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

Published on: November 9, 2019

Area of Science:

  • Environmental biotechnology
  • Wastewater treatment
  • Microbial metabolism

Context:

  • Investigated substrate transformation mechanisms in a laboratory-scale anaerobic-anoxic-oxic (A-A-O) process using real wastewater.
  • Focused on the impact of nitrate presence during the anaerobic stage on microbial processes.

Purpose:

  • To elucidate the substrate transformation pathways under anaerobic conditions with and without nitrate.
  • To quantify the effect of nitrate on phosphorus-accumulating organisms (PAOs) and polyhydroxyalkanoates (PHAs) synthesis.
  • To assess the influence of anaerobic nitrate presence on subsequent anoxic and aerobic phosphorus uptake.

Summary:

  • Without nitrate, PAOs utilized 51% of consumed COD for PHAs storage, with specific phosphorus uptake rates of 3.87 mg/(g·h) (anoxic) and 6.54 mg/(g·h) (aerobic).
  • With nitrate, PAO COD uptake decreased to 30.8%, with 61.5% used for denitrification. Phosphorus uptake rates were lower at 2.24 mg/(g·h) (anoxic) and 4.58 mg/(g·h) (aerobic).
  • Nitrate in the anaerobic phase reduced PAO efficiency and PHAs synthesis, impacting subsequent phosphorus uptake rates, but not the overall phosphorus uptake capacity.

Impact:

  • Provides crucial insights into the competitive role of denitrification versus biological phosphorus removal in A-A-O systems.
  • Highlights the negative effect of nitrate on anaerobic PAO activity and PHAs accumulation.
  • Informs optimization strategies for wastewater treatment plants aiming for enhanced biological nutrient removal.