How many organic compounds exist

The current estimate is around 20 million different organic compounds that we know about. Why the uncertainty? Every day, scientists are coming up with new compounds. Some of these materials are of interest for a research project, while others are destined to be developed for a commercial market.

As soon think we know how many organic compounds exist, more are discovered and our number quickly becomes out of date. At one time in history, it was thought that only living things were capable of synthesizing the carbon-containing compounds present in cells. For that reason, the term organic was applied to those compounds. Eventually it was proved that carbon-containing compounds could be synthesized from inorganic substances, but the term organic has remained.

Currently, organic compounds are defined as covalently bonded compounds containing carbon, excluding carbonates and oxides. By this definition, compounds such as carbon dioxide CO 2 and sodium carbonate Na 2 CO 3 are considered to be inorganic. Organic chemistry is the study of all organic compounds. Organic chemistry is a very vast and complex subject. There are millions of known organic compounds, which is far more than the number of inorganic compounds.

Carbon has four valence electrons and therefore makes four separate covalent bonds in compounds. Carbon has the ability to bond to itself repeatedly, making long chains of carbon atoms as well as ringed structures. These bonds can be single, double, or triple covalent bonds. Carbon readily makes covalent bonds with other elements, primarily hydrogen, oxygen, nitrogen, halogens, and several other nonmetals.

The figure below shows ball-and-stick models of two of the many organic compounds. Stearic acid is composed of many carbon black and hydrogen white atoms, along with two oxygen red atoms. Methionine is composed of carbon, hydrogen, oxygen, nitrogen blue , and sulfur yellow atoms. The related field of biochemistry overlaps to some extent with organic chemistry. Biochemistry is the study of the chemistry of living systems. Many biochemical compounds are considered to be organic chemicals.

Both of the molecules shown above are biochemical materials in terms of their use in the body, but organic chemicals in terms of their structure and chemical reactivity. Read the material at the site below and answer the following questions:. Rethinking Transportation. As our country looks at the prospect of oil shortages in the future, we are searching for alternative transportation fuel sources.

One very viable possibility is propane gas. Power and acceleration for propane-powered vehicles are comparable to gasoline-powered vehicles and fuel efficiency is greater.

Propane has a higher octane rating than regular gasoline, leading to much longer engine life. When properly structured, propane engines can produce lower amounts of air pollution.

We are seeing a growing use of propane in buses, trucks, and police cars. Pictured above is a prototype of a minibus that will run on propane fuel. Maybe your next car will burn propane. A hydrocarbon is an organic compound that is made up of only carbon and hydrogen. A hydrocarbon is the simplest kind of organic molecule and is the basis for all other more complex organic compounds. Hydrocarbons can be divided into two broad categories.

Aliphatic hydrocarbons are hydrocarbons that do not contain the benzene group or a benzene ring. Aromatic hydrocarbons contain one or more benzene rings. In this concept, we will discuss the aliphatic hydrocarbons. An alkane is a hydrocarbon in which there are only single covalent bonds.

The simplest alkane is methane, with the molecular formula CH 4. The carbon is the central atom and makes four single covalent bonds to hydrogen atoms. Methane is the simplest hydrocarbon and is shown with a structural formula, a ball-and-stick model, and a space-filling model. The next simplest alkane is called ethane C 2 H 6 and consists of two carbon atoms with a single covalent bond between them.

Each carbon is then able to bond to three hydrogen atoms. The alkane series progresses from there, increasing the length of the carbon chain by one carbon at a time. Structural formulas for ethane, propane C 3 H 8 , and butane C 4 H 10 are shown below. These alkanes are called straight-chain alkanes because the carbon atoms are connected in one continuous chain with no branches.

Naming and writing structural and molecular formulas for the straight-chain alkanes is straightforward. The name of each alkane consists of a prefix that specifies the number of carbon atoms and the ending —ane. The Table below lists the first ten members of the alkane series. Molecular Formula. Condensed Structural Formula. Note that the table shows a variation of a structural formula called a condensed structural formula. In this formula, the covalent bonds are understood to exist between each carbon and the hydrogens associated with it, as well as between carbon atoms.

This table also shows that the boiling points of the alkanes steadily increase as the length of the carbon chain increases. This is due to an increase in the strength of the intermolecular attractive forces and is a general feature of other organic molecules as well. Read the material at the web site below and answer the following questions:.

Who is my great-aunt? Tracing your family tree can be both fun and exciting. But, it helps to know the exact names of your family members in order to do this correctly.

Just a first name or middle name or last name is not enought. A traceable family tree is one in which all relatives are carefully and precisely identified. After all, you would prefer that great-great-great-uncle to be royalty and not a horse thief. Beginning with butane, there is an alternate structure possible that is not a straight chain.

The structural formulas below show a structure with a three-carbon chain that has a —CH 3 group attached to the middle carbon. The name of this molecule is 2-methylpropane.

The molecular formula is still C 4 H 10 , which is the same formula as butane. A structural isomer is one of multiple molecules that have the same molecular formula, but different structural formulas. Butane and 2-methylpropane are structural isomers. The IUPAC system of nomenclature for branched alkanes follows a set of steps which will be applied to the example molecule below. Work the problems at the link below:. Better Than A Hacksaw. One of the most effective ways to cut metal is with an oxy-acetylene torch.

Very high temperatures are obtained when acetylene burns in oxygen. Safety precautions need to be observed since the gas is very explosive. For welding and cutting, the oxy-acetylene torch is one of the best ways to go. An alkene is a hydrocarbon with one or more carbon-carbon double covalent bonds. The simplest alkene is composed of two carbon atoms and is called ethene shown below. Each carbon is bonded to two hydrogen atoms in addition to the double bond between them.

The hybridization of each carbon atom is sp 2 with trigonal planar geometry. All the atoms of the molecule lay in one plane. Like the alkane series, the names of alkenes are based on the number of atoms in the parent chain. Naming follows the same rules as for alkanes, with the addition of using a number to indicate the location of the double bond.

Propene C 3 H 6 has three carbons total, while butene C 4 H 8 has four. The general formula for alkenes with one double bond is C n H 2n. Alkenes are called unsaturated hydrocarbons. An unsaturated hydrocarbon is a hydrocarbon that contains less than the maximum number of hydrogen atoms that can possibly bond with the number of carbon atoms present. The location of the carbon-carbon double bond can vary.

The 4-carbon alkene generic name is butene. Since the double bond can be located in more than one place, we have 1-butene and 2-butene:. Molecules with multiple double bonds are also quite common. The formula below shows a four-carbon chain with double bonds between carbons 1 and 2 and between carbons 3 and 4. This molecule is called 1,3-butadiene. An alkyne is a hydrocarbon with one or more carbon-carbon triple covalent bonds. The simplest alkyne consists of two carbon atoms and is called ethyne common name: acetylene.

The ethyne molecule is linear, with sp hybridization for each carbon atom. The general formula of alkynes with one triple bond is C n H 2n Alkynes are also unsaturated hydrocarbons. Other alkynes exist, such as 2-pentyne:. Answer the questions at the site below:.

What difference does the isomer make? As we get more into the complexities of organic chemistry, we will see how molecular shape affects reactions. One common reaction for alkenes is the addition of hydrogen across the double bond to form the corresponding alkane. Because of the geometry of the reaction, the different 2-butene shapes have different heats of reaction.

These differences are important both from a theoretical standpoint as well as from the point of view of industrial applications. Greater energy requirements mean a higher cost and a more expensive product. One of the interesting aspects of organic chemistry is that it is three-dimensional. A molecule can have a shape in space that may contribute to its properties. Molecules can differ in the way the atoms are arranged — the same combination of atoms can be assembled in more than one way.

These compounds are known as isomers. Isomers are molecules with the same molecular formulas, but different arrangements of atoms. We will look at some isomer possibilities for alkanes and alkenes. A structural isomer is one in which two or more or organic compounds have the same molecular formulas but different structures. The two pentane molecules below differ only in the location of the methyl group. Alkenes can also demonstrate structural isomerism. In alkenes, there are multiple structural isomers based on where in the chain the double bond occurs.

The condensed structural formulas of 1-butene and 2-butene show this. The number in the name of the alkene refers to the lowest numbered carbon in the chain that is part of the double bond. With a molecule such as 2-butene, a different type of isomerism called geometric isomerism can be observed. Geometric isomers are isomers in which the order of atom bonding is the same but the arrangement of atoms in space is different.

The double bond in an alkene is not free to rotate because of the nature of the pi bond. Therefore, there are two different ways to construct the 2-butene molecule. The image below shows the two geometric isomers, called cis butene and trans butene. The cis isomer has the two single hydrogen atoms on the same side of the molecule, while the trans isomer has them on opposite sides of the molecule. In both molecules, the bonding order of the atoms is the same.

In order for geometric isomers to exist, there must be a rigid structure in the molecule to prevent free rotation around a bond.

If the double bond in an alkene was capable of rotating, the two geometric isomers above would not exist. In addition, the two carbon atoms must each have two different groups attached in order for there to be geometric isomers. Propene has no geometric isomers because one of the carbon atoms has two single hydrogens bonded to it. Physical and chemical properties of geometric isomers are generally different. While cis butene is a polar molecule, trans butene is nonpolar. Heat or irradiation with light can be used to bring about the conversion of one geometric isomer to another.

The input of energy must be large enough to break the pi bond between the two carbon atoms, which is weaker than the sigma bond. At that point, the now single bond is free to rotate and the isomers can interconvert. As with alkenes, alkynes display structural isomerism beginning with 1-butyne and 2-butyne. However, there are no geometric isomers with alkynes because there is only one other group bonded to the carbon atoms that are involved in the triple bond. Watch the video at the link below and answer the following questions:.

From Benzene To Balloons. Although cyclohexane can be isolated from petroleum products, a major source of this chemical is the hydrogenation of benzene. Much of the cyclohexane produced is used to manufacture intermediates for the production of nylon. The nylon balloons pictured above no doubt had their start in a chemical plant where hydrogen gas and benzene were reacted at high temperatures to form cyclohexane. This cycloalkane then undergoes nitration to begin the process of forming the long strands of nylon that can be made into balloons, ropes, clothing, and many other useful products.

A cyclic hydrocarbon is a hydrocarbon in which the carbon chain joins to itself in a ring. A cycloalkane is a cyclic hydrocarbon in which all of the carbon-carbon bonds are single bonds. Like other alkanes, cycloalkanes are saturated compounds. Cycloalkanes have the general formula of C n H 2n. The simplest cycloalkane is cyclopropane, a three-carbon ring. Cyclopropane is the simplest cycloalkane. Its highly strained geometry makes it rather unstable and highly reactive.

The structural formulas of cyclic hydrocarbons can be represented in multiple ways, two of which are shown above. Each atom can be shown as in the structure on the left from the Figure above. A convenient shorthand is to omit the element symbols and only show the shape, as in the triangle on the right. Carbon atoms are understood to be the vertices of the triangle. The carbon atoms in cycloalkanes are still sp 3 hybridized, with an ideal bond angle of This deviation from the ideal angle is called ring strain and makes cyclopropane a fairly unstable and reactive molecule.

This minimal ring strain for cyclopentane makes it a more stable compound. Cyclohexane is a six-carbon cycloalkane shown below. All three of the depictions of cyclohexane are somewhat misleading because the molecule is not planar.

In order to reduce the ring strain and attain a bond angle of approximately The puckering of the ring means that every other carbon atom is above and below the plane. The Figure below shows two possibilities for the puckered cyclohexane molecule. Each of the structures is called a conformation.

The conformation on the right is called the boat conformation, while the one on the left is called the chair conformation. Chair left and boat right conformations for cyclohexane. While both conformations reduce the ring strain compared to a planar molecule, the chair is preferred. This is because the chair conformation results in fewer repulsive interactions between the hydrogen atoms.

However, interconversion readily occurs between the two conformations. Larger cycloalkanes also exist, but are less common. Cyclic hydrocarbons may also be unsaturated.

A cycloalkene is a cyclic hydrocarbon with at least one carbon-carbon double bond. A cycloalkyne is a cyclic hydrocarbon with at least one carbon-carbon triple bond. Shown below are the simplified structural formulas for cyclohexene and cyclooctyne. Name the compounds at the link below:. Can a dream affect reality? He supposedly was thinking about the structure of the benzene ring as he fell asleep.

He used this idea to propose the cyclic structure for benzene. Whether or not he actually had this dream has been debated ever since. Whatever really happened, the tale has persisted until today. Benzene is the parent compound of the large family of organic compounds known as aromatic compounds. Unlike cyclohexane, benzene only contains six hydrogen atoms, giving the impression that the ring is unsaturated and each carbon atom participates in one double bond.

Two different structures with alternating single and double bonds around the ring can be written for benzene. In benzene, the true bonding between carbon atoms is neither a single nor a double bond. Rather, all of the bonds are a hybrid of a single and double bond. In benzene, the pi bonding electrons are free to move completely around the ring. Delocalized electrons are electrons that are not confined to the bond between two atoms, but are instead allowed to move between three or more.

The delocalization of the electrons in benzene can best be shown by showing benzene with a ring inside the hexagon, with the hydrogen atoms understood. Delocalization of the electrons makes for a more stable molecule than a similar molecule that does not have delocalized electrons. Benzene is a more stable and less reactive compound than straight-chain hexenes. The sp 2 hybridization of the carbon atoms results in a planar molecule as opposed to the puckered structure of cyclohexane.

Benzene rings are common in a great number of natural substances and biomolecules. The figure below shows the structural formulas for vanilla and naphthalene.

Naphthalens is a chemical which is commonly used in mothballs. The simplest aromatic compounds are benzene rings with one substituent replacing one of the hydrogen atoms. The molecule shown below is therefore called ethylbenzene. Substituents can be groups other than alky groups.

If a chlorine atom were substituted for a hydrogen, the name becomes chlorobenzene. An —NH 2 group is called an amino group, so the corresponding molecule is called aminobenzene, often referred to as aniline. An —NO 2 group is called a nitro group and so the third example below is nitrobenzene. If more than one substituent is present, their location relative to each other can be indicated by numbering the positions on the benzene ring.

The number of the carbon location then precedes the name of the substituent in the overall name, with the numbers separated by a comma. As with branched alkanes, the system requires that the numbers be the lowest possible and that prefixes be used for more than one of the same substituent.

If there are different substituents, the first in alphabetical order is given the lower number and listed first. Clicking on the table will display examples of these shapes. The covalent bonding in such compounds involves participation of low energy 3d-orbitals,and will be discussed in a later section of this chapter.

The hexafluorides, sulfur hexafluoride,SF 6 , and hexafluorosilicic acid, H 2 SiF 6 , both have octahedral structures. From a valence shell electron count. The latter is a moderately strong acid stable only in water solution. Its salts have seen use as a pesticide. The useful chlorinating agent phosphorous pentachloride, PCl 5 , is formed by reacting PCl 3 with Cl 2.

It decomposes to these reactants on heating. It is necessary to draw structural formulas for organic compounds because in most cases a molecular formula does not uniquely represent a single compound. Different compounds having the same molecular formula are called isomers , and the prevalence of isomers among organic compounds reflects the extraordinary versatility of carbon in forming strong bonds to itself and to other elements.

When the group of atoms that make up the molecules of different isomers are bonded together in fundamentally different ways, we refer to such compounds as constitutional isomers.

There are seven constitutional isomers of C 4 H 10 O, and structural formulas for these are drawn in the following table. These formulas represent all known and possible C 4 H 10 O compounds, and display a common structural feature. There are no double or triple bonds and no rings in any of these structures.

Curiously, if two hydrogens are removed from the molecular formula, giving C 4 H 8 O, the number of constitutional isomers increases to eighteen, and all these compounds have either a ring or a double bond in their structural formulas.

The reason for this will be discussed in the bext section. Simplification of structural formulas may be achieved without any loss of the information they convey. In condensed structural formulas the bonds to each carbon are omitted, but each distinct structural unit group is written with subscript numbers designating multiple substituents, including the hydrogens.

Shorthand line formulas omit the symbols for carbon and hydrogen entirely. Each straight line segment represents a bond, the ends and intersections of the lines are carbon atoms, and the correct number of hydrogens is calculated from the tetravalency of carbon. Non-bonding valence shell electrons are omitted in these formulas. Developing the ability to visualize a three-dimensional structure from two-dimensional formulas requires practice, and in most cases the aid of molecular models.

As noted earlier, many kinds of model kits are available to students and professional chemists, and the beginning student is encouraged to obtain one. Although constitutional isomers have the same molecular formula, their physical and chemical properties may be very different.

For an example Click Here. Even though structural formulas are essential to the unique description of organic compounds, it is interesting and instructive to evaluate the information that may be obtained from a molecular formula alone. Three useful rules may be listed:.

By rule 2 m must be an even number, so if m The presence of one or more nitrogen atoms or halogen substituents requires a modified analysis. The above formula may be extended to such compounds by a few simple principles: The presence of oxygen does not alter the relationship. All halogens present in the molecular formula must be replaced by hydrogen.

Each nitrogen in the formula must be replaced by a CH moiety. When discussing structural formulas, it is often useful to distinguish different groups of carbon atoms by their structural characteristics. The three C 5 H 12 isomers shown below illustrate these terms.

Structural differences may occur within these four groups, depending on the molecular constitution. A consideration of molecular symmetry helps to distinguish structurally equivalent from nonequivalent atoms and groups. The ability to distinguish structural differences of this kind is an essential part of mastering organic chemistry. It will come with practice and experience. Individual molecules are too small to be viewed by even powerful microscopes.

To see how chemists can draw structural formulas with confidence Click Here. The following problems explore many of the concepts discussed above. They include valency, evaluation of line and condensed structural formulas, analyzing molecular formulas and identifying structurally equivalent groups. The number of hydrogen atoms that can be bonded to a given number of carbon atoms is limited by the valence of carbon. The origin of this formula is evident by considering a hydrocarbon made up of a chain of carbon atoms.

Here the middle carbons will each have two hydrogens and the two end carbons have three hydrogens each. Thus, when even-valenced atoms such as carbon and oxygen are bonded together in any number and in any manner, the number of remaining unoccupied bonding sites must be even. If these sites are occupied by univalent atoms such as H, F, Cl, etc. If the four carbon atoms form a ring, two hydrogens must be lost. Organic compounds are all around us. Many modern materials are at least partially composed of organic compounds.

Examples of where you can find organic compounds include agrichemicals, coatings, cosmetics, detergent, dyestuff, food, fuel, petrochemicals, pharmaceuticals, plastics, and rubber. Biotech involves using living organisms and bioprocesses to create or modify products for a specific use.

For example, a biotech company might produce seeds for crops that are disease-resistant, or plants that are drought-resistant. Most consumer products we use involve organic chemistry. Take the cosmetics industry as an example. Organic chemistry examines how the skin responds to metabolic and environmental factors, and chemists formulate products accordingly. Other examples of everyday products that involve organic chemistry include soaps, plastic goods, perfume, coal, and food additives. Crucial to modern world economies, organic industrial chemistry focuses on converting raw materials e.

Today, organic industrial chemistry is based mainly on petroleum and natural gas. Because these are finite raw materials, a lot of industry focus is on learning how to convert renewable resources e. The largest-volume petroleum products are fuel oil and gasoline. Petroleum is also the raw material for many chemical products e. The pharmaceutical industry develops, produces, and markets drugs used as medications for humans or animals. Some pharmaceutical companies deal in brand-name i.

Pharmaceuticals brand name and generic and medical devices are subject to many country-specific laws and regulations regarding patenting, testing, safety assurance, efficacy, monitoring, and marketing. Federal offices e.