• Secondary Carbon Footprint
• Primary Secondary And Tertiary Carbon
• Secondary Carbon Atom
• Secondary Carbon Double Bond
• Secondary Carbon

Secondary carbon. A secondary carbon is a carbon atom bound to two other carbon atoms. For this reason, secondary carbon atoms are found in all hydrocarbons having at least three carbon atoms. In unbranched alkanes, the inner carbon atoms are always. We supply secondary choice carbon steel wire: We are a top level supplier and exporter of secondary carbon steel wire. (secondary grade, 2nd choice quality & overstock prime) We work with the largest steel wire producers in North America, and have been supplying our customers in various countries around the world for over 35 years. The terms secondary and tertiary structure refer to the three-dimensional (3D) conformation of a protein chain. Secondary structure refers to the interactions of the backbone chain (that is, the amide linkages). Tertiary structure refers to interactions of the side chains.

The key difference between primary and secondary allylic carbocations is that primary allylic carbocation is less stable than secondary allylic carbocation.

An allylic carbocation is a resonance stabilized carbon structure. It is an ion containing a positive charge. In these ions, the positive ion is placed on the allylic carbon atom (an allylic carbon atom is the adjacent atom to a double bond). Primary allylic carbocation is an allylic carbocation where the positive charge is placed on a primary carbon atom while secondary allylic carbocation is an allylic carbocation where the positive charge is placed on a secondary carbon atom.

Secondary Carbon Structural formula of propane (secondary carbon is highlighted red): A secondary carbon is a carbon atom bound to two other carbon atoms. For this reason, secondary carbon atoms are found in all hydrocarbons having at least three carbon atoms.

CONTENTS

1. Overview and Key Difference
2. What are Primary Allylic Carbocations
3. What are Secondary Allylic Carbocations
4. Side by Side Comparison – Primary vs Secondary Allylic Carbocations in Tabular Form
5. Summary

What are Primary Allylic Carbocations?

Primary allylic carbocation is an allylic carbocation where the positive charge is placed on a primary carbon atom. It is named as a carbocation because it contains a positive charge on a carbon atom. Usually, an allylic carbocation carries a +1 positive charge. A primary carbon atom is a carbon atom that is attached to two hydrogen atoms and a double bond. Typically, a neutral carbon atom forms four covalent bonds, and one covalent bond is removed when it forms a cation. A primary carbon atom contains only one aryl or alkyl group attached to it while other bonds are C-H bonds.

Generally, a molecule containing double bonds between carbon atoms can have resonance stabilized structures. Resonance means that electrons in the pi bond of the double bond are distributed throughout the molecule as a delocalized system where the stability is increased than in a normal molecule. Therefore, if we are going to name a compound as a primary allylic carbocation, that particular compound should have a positive charge on allylic carbon atoms in all possible resonance structure of that molecule.

What are Secondary Allylic Carbocations?

Secondary allylic carbocation is an allylic carbocation where the positive charge is placed on a secondary carbon atom. It is named as a carbocation because it contains a positive charge on a carbon atom. Usually, an allylic carbocation carries a +1 positive charge. A secondary carbon atom is a carbon atom that is attached to one hydrogen atom, a double bond and an alkyl or aryl group. Typically, a neutral carbon atom forms four covalent bonds where one covalent bond is removed when it forms a cation. A secondary carbon atom contains two aryl or alkyl group attached to it while the other bond is a C-H bonds.

Sometimes, the term secondary allylic carbocation is used when only one resonance structure of a particular compound contains the positive charge on a secondary carbon atom. More importantly, secondary allylic carbocations are more stable than primary allylic carbocations because they have two aryl or alkyl groups attached to the carbon atom bearing the positive charge (aryl or alkyl groups are electron-withdrawing groups so, they can minimize the positive charge on the carbon atom).

What is the Difference Between Primary and Secondary Allylic Carbocations?

Allylic carbocations are chemical structures where the positive charge is on the allylic carbon atom of the molecule. The allylic carbon atom is the carbon atom that is adjacent to a double bond. Primary allylic carbocation is an allylic carbocation where the positive charge is placed on a primary carbon atom while secondary allylic carbocation is an allylic carbocation where the positive charge is placed on a secondary carbon atom. The key difference between primary and secondary allylic carbocations is that the primary allylic carbocation is less stable than the secondary allylic carbocation.

Below tabulation summarizes the differences between primary and secondary allylic carbocations.

Summary – Primary vs Secondary Allylic Carbocations

Allylic carbocations are chemical structures where the positive charge is on the allylic carbon atom of the molecule. The allylic carbon atom is the carbon atom that is adjacent to a double bond. The key difference between primary and secondary allylic carbocations is that the primary allylic carbocation is less stable than the secondary allylic carbocation.

Reference:

1. “Secondary Allylic Carbocation.” Chemistry LibreTexts, Libretexts, 14 July 2020, Available here.

Image Courtesy:

1. “Allylic resonance” By User Tor Svensson – Structure drawn by me (Public Domain) via Commons Wikimedia

Pollutants Released Into The Environment

Research on environmental health has indicated an increased amount of pollutants in the Earth’s atmosphere, waterways, and soil. These pollutants come from a number of sources including: the agricultural industry, manufacturing plants, and urban centers. As countries around the world continue to industrialize their economies and the cities continue to undergo rapid urbanization, the amount of pollutants released into the environment is steadily increasing. Even everyday, seemingly ordinary activities like driving personal automobiles to work makes an impact on the environment by emitting large quantities of contaminants.

Understanding details about which contaminants are making their way into the soil, waterways, and air is important in order to combat any damage they may cause. Some important details include: pollutant source, manner of emission, and interactions in the environment. Without this information, preventing harmful consequences is difficult, if not impossible. This article focuses on the types of pollutants found in air pollution: primary and secondary.

What Is A Primary Pollutant?

Secondary Carbon Footprint

A primary pollutant is emitted from a single source into the air, where it may contaminate natural habitats and concentrate exponentially over time. Some of the most common primary pollutants include: carbon dioxide, nitrogen oxide, chlorofluorocarbons, sulphur dioxide, volatile organic compounds, mercury, and particulate matter. These emissions make their way into the atmosphere by natural causes, like volcanic eruptions, and by human activity, like the manufacturing industry. The main contributor of primary pollutants to the atmosphere, however, is motor vehicle emissions. Burning gasoline and diesel fuel in combustion engines results in significant exhaust emissions.

What Is A Secondary Pollutant?

A secondary pollutant is not a direct emission from a single source. Instead, these pollutants are formed when 2 or more primary pollutants react with each other in the atmosphere. An example of this can be seen when nitrogen oxide and hydrocarbons react with sunlight, resulting in ozone. Another example of a secondary pollutant occurs when nitrogen oxide and sulphur dioxide react with water in the atmosphere, creating acid rain. Other secondary pollutants include: smog, nitrogen dioxide, peroxyacyl nitrates, and sulfuric acid.

The creation of secondary pollutants is influenced by a number of factors, including: particle sizes, concentration levels, UV strength, and external weather conditions. Many experts report that secondary pollutants can cause much greater damage to the environment than primary pollutants. Additionally, these substances are of particular concern given their variability and propensity to form from a wide range of primary pollutants.

How Do Primary Pollutants React In The Atmosphere?

As previously mentioned, several factors can contribute to the creation of secondary pollutants in the atmosphere. One of the most important of these is considered particle size. These solid particles, which can be carried through the air at any time, absorb a small amount of gas particles into their surface level. When this absorption occurs, the gases become stronger, effectively increasing their level of toxicity.

Effects Of Primary And Secondary Pollutants

Researchers have identified a link between primary pollutants and global climate change. Additionally, secondary pollutants are known to cause a number of negative impacts on the environment as well. Primary pollutants in particular are known for their corrosive properties, which can cause damage to ecosystems as well as manmade infrastructure.

When pollutants in the atmosphere present as smog, they may reduce the visibility of an area or cause respiratory and cardiac problems in humans. Some health professionals believe that smog leads to asthma in children as well an increased risk of pneumonia. Animals may also be affected by poor air quality, which forces them to seek out new habitats. This secondary pollutant has become a common occurrence in urban areas around the world, particularly in cities with high population densities. Photochemical smog may consist of several secondary pollutants, such as ozone and nitric acid.

In addition, ozone depletion is one of the effects of primary and secondary pollutants in the atmosphere. Ozone depletion is caused by chlorofluorocarbons, which makes the ozone layers grow thin. Thinner, or in some cases non-existent, ozone permits dangerous solar UV rays to reach the surface of the earth. These UV rays are harmful for plant life and humans. In humans, it can cause vision problems and skin cancer.

Acid rain, a secondary pollutant, occurs anywhere near fossil fuel-burning power plants. This rain, filled with nitrogen and sulphur oxides, flows into waterways, changing marine habitats. Additionally, it may have a negative impact on agriculture harvest yield.

Primary Secondary And Tertiary Carbon

As previously mentioned, primary and secondary pollutants have also been connected to global climate change. One of the results of this has been increasing temperatures around the world. As temperatures increase in colder regions, the melting snow, ice, and glaciers are contributing to rising sea levels. Increases in sea levels are threatening coastal communities, particularly on island nations. As temperatures increase in warmer regions, rainfall decreases. These increased instances of drought often result in desertification.

High levels of pollutants can also be carried to the earth’s surface, where it seeps into groundwater and washes away into waterways. One of the results of this is eutrophication, which is a higher than average concentration of nitrogen in the water. This nitrogen content creates the perfect environment for algae, which soon begins to take over the marine habitat. As algae grows thicker, it blocks the sunlight from entering the water, which prevents the growth of other oxygen-creating marine plants. With less plants in the waters, fish and other marine species are unable to obtain all of their dietary needs. Eventually, eutrophication results in decreased marine animal life as well.

Secondary Carbon Atom

Preventing Air Pollution

Given that private transportation is one of the main contributors of primary pollutants to the atmosphere, reducing the use of combustion engine vehicles is one of the principal means of preventing air pollution. Experts suggest increasing the use of public transportation or to ride to work in carpools, anything to reduce the number of automobiles on the road.

Secondary Carbon Double Bond

Other ways to prevent primary pollutants from entering the atmosphere (and resulting in secondary pollutants) is by investing in renewable energy. Showing support for and demanding renewable energies could prompt more governments around the world to invest in solar, wind, and hydro infrastructure to meet energy needs. Where this is not available, concerned individuals can reduce their use of energy by taking some simple steps throughout their day, like turning off the lights and other electronic appliances when not in use.

Secondary Carbon

Staying informed and urging governments and private organizations to take steps to reduce primary pollutant emissions is one of the best ways to fight air pollution and climate change.