File Name: structural formula of alkanes alkenes and alkynes .zip
Most reactions of organic compounds take place at or adjacent to a functional group. In order to establish a baseline of behavior against which these reactions may be ranked, we need to investigate the reactivity of compounds lacking any functional groups.
Such compounds are necessarily hydrocarbons , made up of chains and rings of carbon atoms bonded to a full complement of hydrogen atoms all carbons are sp 3 hybridized. Hydrocarbons of this kind are classified as alkanes or cycloalkanes , depending on whether the carbon atoms of the molecule are arranged only in chains or also in rings. Although these hydrocarbons have no functional groups, they constitute the framework on which functional groups are located in other classes of compounds, and provide an ideal starting point for studying and naming organic compounds.
Alkanes and cycloalkanes are termed saturated , because they incorporate the maximum number of hydrogens possible without breaking any carbon-carbon bonds. They are also members of a larger class of compounds referred to as aliphatic.
Simply put, aliphatic compounds are compounds that do not incorporate any unsaturated aromatic rings in their molecular structure. The increasingly large number of organic compounds identified with each passing day, together with the fact that many of these compounds are isomers of other compounds, requires that a systematic nomenclature system be developed.
Just as each distinct compound has a unique molecular structure which can be designated by a structural formula, each compound must be given a characteristic and unique name. Common Names As organic chemistry grew and developed from its early beginnings, many compounds were given trivial names at the time of their discovery.
These names have remained in common use, and are widely recognized. The relationship of these names to each other is usually arbitrary, and no rational or systematic principles underly their assignments. Some examples are:.
Common names such as these often have their origin in the history of the science and the natural sources of specific compounds. The relationship of these names to each other is arbitrary, and no rational or systematic principles underly their assignments. Consequently, common names can only be remembered by repeated use, in much the same way we use nicknames. A rational nomenclature system should do at least two things: First , it should indicate how the carbon atoms of a given compound are bonded together in a characteristic lattice of chains and rings.
Second , it should identify and locate any functional groups present in the compound. Since hydrogen is such a common component of organic compounds, its quantity and location can be assumed from the tetravalency of carbon, and need not be specified in most cases.
Knowing these rules and given a structural formula, one should be able to write a unique name for every distinct compound. A root or base indicating a major chain or ring of carbon atoms found in the molecular structure. A suffix or other element s designating functional groups that may be present in the compound. As an introduction to the IUPAC nomenclature system, we shall first consider the alkanes and cycloalkanes, since these compounds provide the foundation on which the nomenclature of functional groups is built.
To use this site Click Here. A common "ane" suffix identifies these compounds as alkanes. Longer chain alkanes are well known, and their names may be found in many reference and text books.
The names methane through decane should be memorized, since they constitute the root of many IUPAC names. Fortunately, common numerical prefixes are used in naming chains of five or more carbon atoms. Some important behavior trends and terminologies: i. The formulas and structures of these alkanes increase uniformally by a CH 2 increment. A uniform variation of this kind in a series of compounds is called homologous.
Beginning with butane C 4 H 10 , and becoming more numerous with larger alkanes, we note the existence of alkane isomers. For example, there are five C 6 H 14 isomers, shown below as abbreviated line formulas A through E :. Although these distinct compounds all have the same molecular formula, only one A can be called hexane.
How then are we to name the others? The IUPAC system requires first that we have names for simple unbranched chains, as noted above, and second that we have names for simple alkyl groups that may be attached to the chains. Examples of some common alkyl groups are given in the following table.
Note that the "ane" suffix is replaced by " yl " in naming groups. The symbol R is used to designate a generic unspecified alkyl group.
Find and name the longest continuous carbon chain. Identify and name groups attached to this chain. Number the chain consecutively, starting at the end nearest a substituent group. Designate the location of each substituent group by an appropriate number and name. Assemble the name, listing groups in alphabetical order. The prefixes di, tri, tetra etc. Halogen substituents are easily accomodated, using the names: fluoro F- , chloro Cl- , bromo Br- and iodo I-.
If the halogen is bonded to a simple alkyl group an alternative "alkyl halide" name may be used. Thus, C 2 H 5 Cl may be named chloroethane no locator number is needed for a two carbon chain or ethyl chloride. Cycloalkanes have one or more rings of carbon atoms. The simplest examples of this class consist of a single, unsubstituted carbon ring, and these form a homologous series similar to the unbranched alkanes.
The last yellow shaded column gives the general formula for a cycloalkane of any size. If a simple unbranched alkane is converted to a cycloalkane two hydrogen atoms, one from each end of the chain, must be lost. Hence the general formula for a cycloalkane composed of n carbons is C n H 2n. Substituted cycloalkanes are named in a fashion very similar to that used for naming branched alkanes.
The chief difference in the rules and procedures occurs in the numbering system. Since all the carbons of a ring are equivalent a ring has no ends like a chain does , the numbering starts at a substituted ring atom. For a monosubstituted cycloalkane the ring supplies the root name table above and the substituent group is named as usual. A location number is unnecessary.
If two different substituents are present on the ring, they are listed in alphabetical order, and the first cited substituent is assigned to carbon 1. The numbering of ring carbons then continues in a direction clockwise or counter-clockwise that affords the second substituent the lower possible location number. If several substituents are present on the ring, they are listed in alphabetical order.
Location numbers are assigned to the substituents so that one of them is at carbon 1 and the other locations have the lowest possible numbers, counting in either a clockwise or counter-clockwise direction. The name is assembled, listing groups in alphabetical order and giving each group if there are two or more a location number. Small rings, such as three and four membered rings, have significant angle strain resulting from the distortion of the sp 3 carbon bond angles from the ideal This angle strain often enhances the chemical reactivity of such compounds, leading to ring cleavage products.
It is also important to recognize that, with the exception of cyclopropane, cycloalkyl rings are not planar flat. The three dimensional shapes assumed by the common rings especially cyclohexane and larger rings are described and discussed in the Conformational Analysis Section.
Hydrocarbons having more than one ring are common, and are referred to as bicyclic two rings , tricyclic three rings and in general, polycyclic compounds. The structural relationship of rings in a polycyclic compound can vary. They may be separate and independent, or they may share one or two common atoms.
Some examples of these possible arrangements are shown in the following table. Hydrocarbons incorporating double or triple carbon-carbon bonds are called unsaturated because hydrogen can be added to the multiple bond, converting the compound to an alkane or cycloalkane.
Such compounds are called alkenes and alkynes respectively. Because they are isomeric with cycloalkanes or bicycloalkanes, their names must clearly convey the presence of functional unsaturation.
This is done by changing the ane suffix in the name of an alkane to ene for a double bond, or yne for a triple bond, as illustrated by the following examples. The location of a multiple bond in a chain is designated by a number, just as is done for substituents on a chain. A complete treatment of alkene and alkyne nomenclature is presented below. Alkenes and alkynes are hydrocarbons which respectively have carbon-carbon double bond and carbon-carbon triple bond functional groups.
The molecular formulas of these unsaturated hydrocarbons reflect the multiple bonding of the functional groups:. As noted earlier in the Analysis of Molecular Formulas section, the molecular formula of a hydrocarbon provides information about the possible structural types it may represent.
For example, consider compounds having the formula C 5 H 8. The formula of the five-carbon alkane pentane is C 5 H 12 so the difference in hydrogen content is 4. This difference suggests such compounds may have a triple bond, two double bonds, a ring plus a double bond, or two rings. Some examples were shown above, and there are at least fourteen others! The ene suffix ending indicates an alkene or cycloalkene.
The longest chain chosen for the root name must include both carbon atoms of the double bond. The root chain must be numbered from the end nearest a double bond carbon atom. If the double bond is in the center of the chain, the nearest substituent rule is used to determine the end where numbering starts. The smaller of the two numbers designating the carbon atoms of the double bond is used as the double bond locator.
If more than one double bond is present the compound is named as a diene, triene or equivalent term, indicating the number of double bonds. Each double bond is assigned a locator number. In cycloalkenes the double bond carbons are assigned ring locations 1 and 2. Which of the two is 1 may be determined by the nearest substituent rule.
The yne suffix ending indicates an alkyne or cycloalkyne. The longest chain chosen for the root name must include both carbon atoms of the triple bond. The root chain must be numbered from the end nearest a triple bond carbon atom. If the triple bond is in the center of the chain, the nearest substituent rule is used to determine the end where numbering starts. The smaller of the two numbers designating the carbon atoms of the triple bond is used as the triple bond locator.
Make sure that your printout includes all content from the page. If it doesn't, try opening this guide in a different browser and printing from there sometimes Internet Explorer works better, sometimes Chrome, sometimes Firefox, etc. Hydrocarbons are the simplest organic compounds, but they have interesting physiological effects. These effects depend on the size of the hydrocarbon molecules and where on or in the body they are applied. Alkanes of low molar mass—those with from 1 to approximately 10 or so carbon atoms—are gases or light liquids that act as anesthetics. Swallowed, liquid alkanes do little harm while in the stomach. The lungs become unable to expel fluids, just as in pneumonia caused by bacteria or viruses.
I agree Our site saves small pieces of text information cookies on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing our website without changing the browser settings you grant us permission to store that information on your device. Alkanes, alkenes and alkynes are simple hydrocarbon chains with no functional groups. The simplest organic compounds are the alkanes.
Most reactions of organic compounds take place at or adjacent to a functional group. In order to establish a baseline of behavior against which these reactions may be ranked, we need to investigate the reactivity of compounds lacking any functional groups. Such compounds are necessarily hydrocarbons , made up of chains and rings of carbon atoms bonded to a full complement of hydrogen atoms all carbons are sp 3 hybridized. Hydrocarbons of this kind are classified as alkanes or cycloalkanes , depending on whether the carbon atoms of the molecule are arranged only in chains or also in rings.
In chemistry , an alkene is a hydrocarbon that contains a carbon —carbon double bond. The term is often used as synonym of olefin , that is, any hydrocarbon containing one or more double bonds. Acyclic alkenes, with only one double bond and no other functional groups also known as mono-enes form a homologous series of hydrocarbons with the general formula C n H 2 n with n being 2 or more which is two hydrogens less than the corresponding alkane.
The largest database 1 of organic compounds lists about 10 million substances, which include compounds originating from living organisms and those synthesized by chemists. The number of potential organic compounds has been estimated 2 at 10 60 —an astronomically high number. The existence of so many organic molecules is a consequence of the ability of carbon atoms to form up to four strong bonds to other carbon atoms, resulting in chains and rings of many different sizes, shapes, and complexities. The simplest organic compounds contain only the elements carbon and hydrogen, and are called hydrocarbons.
Alkanes belong to the family of saturated hydrocarbons that is; they contain only sigma bond linkages between carbon and hydrogen.
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Беккер понял, что перегнул палку. Он нервно оглядел коридор. Его уже выставили сегодня из больницы, и он не хотел, чтобы это случилось еще. - Nimm deinen FuB weg! - прорычал немец. - Уберите ногу.
Он сам считает как фокусник. Она знала, что он перемножает цифры и намертво запоминает словари, не хуже ксерокса. - Таблица умножения, - сказал Беккер. При чем здесь таблица умножения? - подумала Сьюзан. - Что он хочет этим сказать.
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Aromatic hydrocarbons are defined by having 6-membered ring structures with Union of Pure and Applied Chemistry (IUPAC) names for alkynes parallel.