Structure and stereochem slide 319 reactions of alkanes combustion complete oxidation of an organic molecule in the presence of oxygen. Members of a group of compounds, such as the alkanes, that have simi lar chemical structures and graded physical properties, and which differ from. In this system, a series of rules has been created that is adaptable to all classes of organic compounds. Structure and stereochemistry of alkanes organic chemistry, 5th edition l. If more than one different chains are of equal length number of carbons, choose the one with the greater number of branch points. Unsaturated hydrocarbons have double or triple bonds and are quite reactive. Elimination reactions alkenes olefins are hydrocarbons that contain a carboncarbon double bond and are said to be unsaturated. Structure and nomenclature chapter 5 2 unsaturated hydrocarbon. Branchedchain alkanes do not exhibit the same smooth gradation of physical properties as do the continuouschain alkanes.
Alkanes are rarely prepared from other types of compounds because of economic reasons. Well, of course, theres one, two, and three carbons. Molecular and structural formula of alkanes youtube. Contains a carboncarbon double bond and has the general formula c nh 2n. Simply put, aliphatic compounds are compounds that do not incorporate any aromatic rings in their molecular structure. The following table lists the iupac names assigned to simple continuouschain alkanes from c1 to c10. Alkanes are less dense than water and swim on top of water. Classification of alkane there are three types of alkanes. Carbons in the middle of a chain are attached to two hydrogens. This chapter describes the skeleltal isomerism of alkanes and cycloalkanes, their threedimensional conformations, and their systematic nomenclature that is the basis for the names of all other organic compounds.
Apr 04, 2018 introduction to alkane alkanes are saturated hydrocarbon consist of carbon and hydrogen only without any functional group. The alkanes and cycloalkanes are also members of a larger class of compounds referred to as. Methane gas is the first member of the homologous series of alkanes. Structure of alkenes 8 cis,trans isomerism in alkenes cis,trans isomers. As such, the geometry of the alkene is preserved in the product.
Structural isomers just how many structures can you make. Learn the important physical and chemical properties of the alkanes. Jul 30, 2018 alkanes, hydrocarbons, class 11 the acyclic saturated hydrocarbons are called paraffins since they are relatively unreactive towards most of the reagents such as acids, bases oxidizing and reducing agents. Molecular and structural formulas the alkynes comprise a series of carbon. The cf bond is much more resistant to uv light than the ccl bond. Boiling points of alkanes branched alkanes have less surface area contact, so weaker intermolecular forces. However, ignoring financial considerations, alkanes can be prepared from the following compounds. The cyclopropanation reaction of an alkene with a carbene takes place in a single step. We begin our study of organic chemistry with the hydrocarbons, the simplest organic compounds, which are composed of carbon and hydrogen atoms only. Chapter 3 2 alkane formulas four carbonor hydogen atoms bonded to each carbon atom all cc single bonds ratio.
Alkanes formula, definition, structure, properties. Alkanes are organic compounds that consist entirely of singlebonded carbon and hydrogen atoms and lack any other functional groups. The simplest of the functional groups are the hydrocarbons, which include the alkanes. Since all alkanes are similar in structure and properties, they are called a homologous series. However, ignoring financial considerations, alkanes can be prepared from. The alkanes and cycloalkanes are also members of a larger class of compounds referred to as aliphatic.
Alkanes and alkyl groups can be subclassified as aliphatic acyclic or cycloaliphatic based on their general structure. They are unsaturated compounds with at least one carbontocarbon double bond. A summary of nomenclature and isomerism in s organic chemistry. A hydrocarbon molecule contains only carbon and hydrogen. Cycloaliphatics or cycloalkanes contain the alkane or alkyl fragment as part of a carbon cycle. Simply put, aliphatic compounds are compounds that do not incorporate any. Notice that both of these molecules contain only f halogen atoms and no cl atoms. If you have fluorine coming off of the carbon chain, it is named as fluoro. Structural isomers just how many structures can you make from a simple formula. Pdf effect of chemical structure on secondary organic. Molecular and structural formulas the alkanes comprise a series of compounds that are composed of carbon and hydrogen atoms with single covalent bonds. Carbon has a valence of four and thus requires four electrons or bonds to complete its octet in the neutral state. The base name of alkanes is derived from the greek for the number of carbons in the longest continuous carbon chain table 2.
In addition to our examination of alkanes, we will also take a brief look. The base name of cycloalkanes is based on the greek for the number of carbons in the ring with the prefix cyclo and the suffix ane. Structural formulas division of the family of hydrocarbons visualization of an alkanes structure alkanes acetylene cycloparaffins alcohol. Fgs behave similarly in every molecule they are part of. Alkane and cycloalkane nomenclature ii our mission is to provide a free, worldclass education to anyone, anywhere. Thus, given the number of carbon atoms in an alkane, it is easy to determine the number of hydrogens in the molecule. Alkene nomenclature please read and understand prefixparentsuffix suffix for alkenes. When it comes to halogens, you have to change the ending ine to o. Within alkane structure there is free rotation about the carbontocarbon single bonds. Learn exactly what happened in this chapter, scene, or section of organic chemistry. Name the longest straight unbranched carbon chain in the structure. Hfa 4a has the structure and the systematic name 1,1,1,2tetrafluoroethane hfa 227 has the wedge and dash structure and the systematic name 1,1,1,2,3,3,3heptafluoropropane. C2h6 once the two carbons are connected, there are only six additional bonding sites and these are filled by the six hydrogen atoms. The ability of carbon atoms to form strong, stable bonds with other.
What is the general formula for a noncyclic alkane. Yet another representation of molecular structural formulas. We will include compounds which contain a c bonded to a halogen also c1, f, br, i. Another shorthand representation of alkanes the bondline formula. Learn how to recognize the alkane functional group in organic compounds. As noted before, alkenes are hydrocarbons with carbontocarbon double bonds r 2 ccr 2 and alkynes are hydrocarbons with carbontocarbon triple bonds rc. When the chain is longer than 3 carbons, number the atoms such that the double bond is given the lowest number i.
Alkanes are organic compounds containing carbon and hydrogen with single bonds only. Pdf chapter 3 structure and stereochemistry of alkanes. These carbon atoms already have four electrons, but they each want to get four more so that they have a full eight in the valence shell. The lewis structures and models of methane, ethane, and pentane are illustrated in figure \\pageindex1\.
Cyclic structure containing heteroatoms are called heterocyclic. Principles of drug action 1, spring 2005, alkanes 1 hydrocarbon structure and chemistry. If you observe the structure, three types of chains are possible two chains each with 6 carbons and another chain with 5. Draw structural formulas for the three constitutional isomers with molecular formula c5h12. Well be learning about different aspects of molecular structure, including common functional groups and conformations. Ultradur, pbt is a plastic polymer that contains an aromatic functional group. Hydrocarbons are further divided into several structural types called, alkanes, alkenes, alkynes and. Learn how to write condensed, expanded, and line structures for organic compounds. Since all alkanes are similar in structure and properties, they are called a homologous series the structure of an alkane, as with all hydrocarbons, can be represented with a. Isomers that have the same connectivity but a different arrangement of their atoms in space due to the presence of either a ring chapter 2 or a carboncarbon double bond. Alkane and cycloalkane nomenclature i video khan academy. For butane and related molecules, the important conformations are eclipsed and staggered including gauche and anti.
An eightcarbon alkane has a molecular formula c 8h 18 and structural formulaalkanes list. Learn the iupac system for naming alkanes and cycloalkanes. Alkanes that have carbons that are bonded to more than 2. Groups that are cis on the alkene will end up cis on the cyclopropane product. Carbons on the end of a chain are attached to three hydrogens. Draw the structural formula and line angle formula for the following molecules.
Perfect for acing essays, tests, and quizzes, as well as for writing lesson plans. The list of some alkanes and the molecular formula is given below. The properties of organic molecules depend on the structure, and knowing the names of organic compounds allow us to communicate with other chemists. Preceding the name of the longest chain, write down in alphabetical order the names of each of the alkyl groups which are attached to the main chain. For alkenes, alkynes and aromatic hydrocarbons, spring models can be constructed. Alkanes, or saturated hydrocarbons, contain only single covalent bonds between carbon atoms. Each of the carbon atoms in an alkane has sp 3 hybrid orbitals and is bonded to four other atoms, each of which is either carbon or hydrogen.
The earliest nomenclature systems followed almost no systematic rules. Introduction hydrocarbons are organic compounds consisting of cc and ch bonds. For making models of alkanes, you can use toothpicks for bonds and plasticine balls for atoms. If there are several groups of the same kind, list the group only once, using. The simplest alkane, methane, has one carbon atom and a molecular formula of ch 4. This chapter begins with the study of the simplest organic molecules. Ch4 c h h h h ch4 c h h condensed formula 2d formula 3d formula methane 2. Draw the line bond structures of following types of hydrocarbons using four carbon atoms. Monocyclic alkanes with no side chains are named similarly to acyclic alkanes, but with the prefix cycloattached to the parent hydride name e. They consist of the elements carbon and hydrogen, and all the bonds between the carbon atoms are single bonds. Structures and names of alkanes chemistry libretexts. A halogen is also treated as a substituent when it comes to naming alkanes.
Chapter 3 structure and stereochemistry of alkanes. Boiling points, melting points, and densities generally increase with the size of the alkane. To work out the best way to distinguish alkanes from alkenes. Alkanes, hydrocarbons, class 11 the acyclic saturated hydrocarbons are called paraffins since they are relatively unreactive towards most of the reagents such as acids, bases oxidizing and reducing agents. These are organic molecules that consist only of hydrogen and carbon atoms in a treeshaped structure acyclic or not a ring.
Branched alkanes normally exhibit lower boiling points than unbranched alkanes of the same carbon content. For substituted and unsubstituted cyclohexanes, the most important conformation is the chair. Groups that are trans on the alkene will end up trans on the cyclopropane product. The double bond makes alkenes more reactive than alkanes. Alkanes chemical nomenclature assigns compounds a unique name that allows them to be easily identified and structurally understood. In an alkane, all 4 4 4 valencies of the carbon atom are satisfied with other hydrogen atoms. Alkanes formula, definition, structure, properties, videos. Of the hydrocarbons, the most basic molecules are alkanes, which consist of only single bonds. Alkanes are the saturated hydrocarbons without any functional group so iupac naming is somewhat easy so, lets go with simple examples initially and then to more advanced structures of alkanes. Identify each as an alkane, an alkene, or an alkyne. An eightcarbon alkane has a molecular formula c 8h 18 and structural formula alkanes list. Each atom is attached to the sufficient hydrogen atoms to develop a total of four single covalent bonds. Alkanes and cycloalkanes 11 million organic compounds which are classified into families according to structure and reactivity functional group fg. Now lets go with more advanced examples and lets apply all iupac rules to get the name.
In structures ii, iv and v, you observed that ch3 group is attached to carbon atom numbered as 2. Name the molecules below are there geometric isomers of the above two structures. Alkane names, formulas, properties memorize sections 3. Physical properties of alkanes alkanes are nonpolar only dispersion forces act between molecules. Since we are naming alkanes, our first role is to identify the longest chain. Chapter 3 22 melting points of alkanes branched alkanes pack more efficiently into a crystalline structure, so have higher m. Microsoft word practice problems on alkane nomenclature. Alkanes can be subdivided into the following three groups. The physical properties of alkenes are similar to those of the alkanes. If you are an advanced reader, you can jump to examples given at the end of this article. If you go on constructing structures for higher alkanes, you will be getting still larger number of isomers.
Draw conformations of alkanes and cycloalkanes when given the name, and identify conformations when given a structure. Organic molecules are often organized by structures called functional groups, which are characteristic arrangement of atoms which define many of the physical and chemical properties of a class of organic compounds. Since alkanes are the most fundamental types of organic compounds, their structural features a basic carbon chain, or skeleton provide the basis for the nomenclature of all organic compounds. Alkane names are based on the number of carbon atoms. Aug 12, 2019 to identify and name simple straightchain alkanes given formulas and write formulas for straightchain alkanes given their names.
Alkanes, cycloalkanes, and functional groups khan academy. This group of compounds is a homologous series with the general molecular formula of c n h 2 n 2, where n equals any integer greater than one. Aliphatic alkanes are linear or branched structures as shown in the example above. As these bonds are all single bonds, there is free rotation around all connections. Alkane structure, properties and examples chemistry dictionary. Cycloalkanes are alkanes arranged in a cyclic structure. Ch 3 ch ch ch 2 ch 2 ch 2 ch 2 ch 3 ch 3 ch 3 7 carbons heptb. The international union of pure and applied chemistry iupac is the organization that assigns names to chemical compounds, and these names generally have three. Usually there is too great a variation in molecular structure for regularities to be apparent. Collectively, they are called unsaturated hydrocarbons because they have fewer hydrogen atoms than does an alkane with the same number of carbon atoms. If a noncyclic alkane contains 15 carbon atoms, how many hydrogen atoms does it contain. In organic chemistry, an alkane, or paraffin a historical name that also has other meanings, is an acyclic saturated hydrocarbon. Although many different types of nomenclature, or naming systems, were employed in the past, today only the international union of pure and applied chemistry iupac nomenclature is acceptable for all scientific publications.
Since alkanes are the major components of petroleum and. Aromatic hydrocarbons are defined by having 6membered ring structures with alternating double bonds fig 8. As in the previous examples, giving the smallest number to the cc takes priority over giving a small number to the methyl branch. Draw the structure of an alkane when given its name. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carboncarbon bonds are single. Their adjacent atoms are connected with sigma bonds and form tetrahedral centers around the carbon atoms. Organic chemistry is concerned with the study of the structure and properties of compounds containing carbon. Effect of chemical structure on secondary organic aerosol formation for c12 alkanes article pdf available in atmospheric chemistry and physics 4. Aromatic hydrocarbons contain the 6membered benzene ring structure a that is characterized by alternating double bonds. Ethene an alkene h c c h h h unsaturated hydrocarbons. Alkanesandalkenesworksheet how can we distinguish between alkanes and alkenes.