Alkanes are generally in towards acids, bases, oxidizing and reducing agents. Physical properties of alkanes alkanes are nonpolar only dispersion forces act between molecules. A small difference in the molecule changes the name and can drastically change the reactivity of the compound. A radical chain process will continue until a termination step. Alkenes and alkynes are much more reactive than alkanes. General methods of preparation of alkanes wurtz reaction. Alkane names, formulas, properties memorize sections. A systematic method for the naming of many organic compounds is contained in the iupac publication. Pdf homologation reactions of alkanes on transitionmetal.
Alkanes the most basic of all organic compounds undergo very few reactions. If two different alkyl halides are used to prepare an alkane with odd number of carbon atoms, a mixture of three alkanes is actually produced. Finally, we shall study some chemical reactions of alkanes and cycloalkanes. The international union of pure and applied chemistry iupac is the organization that assigns names to chemical compounds, and these names generally have three. At room temperature alkanes do not react with acids, bases, or strong oxidizing agents. Tes global ltd is registered in england company no 02017289 with its registered office at 26 red lion square london wc1r 4hq. However, anyone who has used a match to light a gas burner, or dropped a match onto charcoal coated with lighter fluid, should recognize that alkanes burst into flame in the presence of a spark.
This is because the cc bond and the ch bond are relatively strong. As such, the geometry of the alkene is preserved in the product. Alkanes are rarely prepared from other types of compounds because of economic reasons. To me it appears like a primeval tropical forest full of the most remarkable things, a dreadful endless jungle into. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carboncarbon bonds are single. Janice gorzynski smith university of hawaii chapter 4 alkanes. Alkanes are stable compounds and are generally unreactive. Depending on the structure of the alkene and the specific reagents, the reactions can be regioselective andor stereoselective. Learn the iupac system for naming alkanes and cycloalkanes. This is because the reaction between c 2 h 4 and chlorine gives c 2 h 2 cl 2, oil. This reaction is known as wurtz reaction and used for the preparation of symmetrical alkanes. As a result alkanes do not react with electron rich species. Reactions of alkanes the alkanes and cycloalkanes, with the exception of cyclopropane, are probably the least chemically reactive class of organic compounds.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. In the presence of certain catalysts called initiators, many alkenes form polymers by the addition of monomers greek. But the y burn well in a good supply of oxygen, forming carbon dioxide and water vapour. Properties of alkanes alkenes and alkynes nomenclature isomers preparation of alkenes and alkynes. Wurtz reaction is a convenient method for the preparation of symmetrical alkanes i.
Alkyl halides except alkyl fluorides on reduction with zinc and dilute hydrochloric acid produce alkanes. Lowmolecularweight alkanes are still soluble enough so that a direct uptake of the alkane from water can assure a sufficient masstransfer to the cell. Alkanes are less dense than water and swim on top of water 2. Functional groups and simple chemical reactions learnt in higher chemistry in the. Jul 17, 2019 the compounds formed by the replacement of one or more hydrogen atoms of alkanes by deriavtives atoms are called halogen derivatives of alkanes. Reactions of alkenes reactions of alkenes electrophilic catalytic carbene oxidative addition halohydrogenation acid catalyzed hydration oxymercurationdemercuration hydroborationoxidation hydrogenation cyclopropanation halogenation halohydrin formation epoxidation antihydroxylation synhydroxylation oxidative cleavage via. Alkanes when we combine the two high bond enthalpy and being nonpolar this makes alkanes quite unreactive alkanes dont react with acidsbases or oxidizing agents this is a useful trait and alkanes are used as lubricating agents and the backbone of polymers but when the do react look out. Number core chain from an end nearest a substituent 3. B halogenation halogenation a substitution reaction.
In the presence of a flame, the reactions are rather like the fluorine one producing a mixture of carbon and the hydrogen halide. In the absence of a spark or a highintensity light source, alkanes are generally inert to chemical reactions. Nomenclature of organic chemistry 1979 and clarified in a guide to iupac nomenclature of organic compounds recommendations 1993. Alkanes 2 organic chemistry nowadays almost drives me mad. Preparations alkenes are generally prepared through. What is the difference between alkanes and alkenes. Unsaturated hydrocarbons have double or triple bonds and are quite reactive. Dealing with organic compounds in chemistry can feel overwhelming. Alkanesandalkenesworksheet how can we distinguish between alkanes and alkenes. Alkane names, formulas, properties memorize sections 3.
The most important application of alkanes is in oxidation reactions. Reactions of alkenes since bonds are stronger than bonds, double bonds tend to react to convert the double bond into bonds this is an addition reaction. The violence of the reaction drops considerably as you go from fluorine to chlorine to bromine. Alkanes, alkenes and halogenoalkanes lesmahagow high school. In the presence of ultraviolet light a halogen will substitute a hydrogen in an alkane, a halogenoalkane and hydrogen halide is produced. Halogenation of alkanes substitution reactions alkanes are unreactive due to the lack of polarity. Difference between alkanes and alkenes compare the. Boiling points, melting points, and densities generally increase with the size of the alkane. Alkane being saturated compounds can undergo only substitution reactions. Alkanes are comprised of a series of compounds that contain carbon and hydrogen atoms with single covalent bonds. Addition of hydrogen halides to symmetrical alkenes the regioselective reaction of the carboncarbon double bond in alkenes with hydrohalogens hx is a controlled by carbocation stability. Freeradical halogenation of alkanes among the methods used in industry, and occasionally in the laboratory, to produce simple alkyl halides is direct halogenation of alkanes.
Despite their relative inertness, alkanes undergo several important reactions that are discussed in the following section. By reduction of alkyl halides rx haloalkanes rx when heated with reducing agents like. Other types of reaction have been substitution and elimination. An example of halogenation chlorination of methane produces chloromethane, dichloromethane, trichloromethane, and tetrachloromethane. This reaction is an addition reaction the halogen atoms will add at the site of the double bond only. The result is the joining of the two alkyl groups from two molecules of. The physical properties of alkenes are similar to those of the alkanes. Most chemical reactions require a functional group. In the presence of a flame, the reactions are rather like the fluorine one producing a mixture of carbon and the hydrogen. This reaction is the most common reaction alkanes undergo. The activation energy for cc coupling reactions was found to be higher following promotion of a ru catalyst with v. However, all saturated hydrocarbons are attacked by oxygen at ele vated temperatures and, if oxygen is in excess, complete combustion to carbon dioxide and water occurs. Organic chemistry science at yorkdale with jessica.
If two molecules can only be interconverted by breaking a bond and then reforming it somewhere else in the molecule, they are structural isomers. Substitution reactions in a substitution reaction a halogen replaces a hydrogen in an alkane in this reaction, two bonds must be broken. Chemsketch molecular modelling activity you have learnt 7 important concepts. Alkanes are quite inert substances with highly stable nature.
Alkanes answers to problems 1 c and d are the same. Groups that are cis on the alkene will end up cis on the cyclopropane product. Branched alkanes containing three or more carbon atoms in their longest chain have isomers with unique names iii. These reactions are employed to illustrate how we can predict and use energy changesparticularly ah, the heat evolved or absorbed by a reacting system, which often can be estimated from bond ener gies. The reactions between alkanes and chlorine or bromine there is no reaction in the dark. In organic chemistry, an alkane, or paraffin a historical name that also has other meanings, is an acyclic saturated hydrocarbon. Cliffsnotes study guides are written by real teachers and professors, so no matter what youre studying, cliffsnotes can ease your homework headaches and help you score high on exams. General methods of preparation of alkanes is the topic which has a potential of fetching a question in iit jee and jee mainadvanced examination very frequently. The two reactions of more importaces is combustion and halogenation, i. The reactions between alkanes and chlorine or bromine. Pdf organic chemistry made easy for senior secondary schools.
The 3d representations and ballandstick models for these alkanes indicate the. Identify each as an alkane, an alkene, or an alkyne. Metathesis of alkanes and related reactions request pdf. Pdf on may 27, 2017, adebayo bamidele olanrewaju and others published organic chemistry. Reactions of alkanes ib combustion of alkanes alkanes are unreactive as a family because of the strong cc and ch bonds as well as them being nonpolar compounds. Applying heat and a catalyst can crack larger, more complex alkanes and produce smaller, more useful alkanes and alkenes. In addition to carbon dioxide, water and heat a variety of products are possible. Since alkanes dont really have functional groups, they arent very useful in many. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The interesting reactions happen in the presence of ultraviolet light sunlight will do.
This holds true for the two compound groups, alkanes and alkenes. Learn substitution reaction alkanes with free interactive flashcards. Groups that are trans on the alkene will end up trans on the cyclopropane product. Haloalkanes alkyl halides react with metallic sodium in dry ether to form symmetrical alkanes with double the number of carbon atoms present in the alkyl halide. This website and its content is subject to our terms and conditions. An alkyl halide on wurtz reaction leads to the formation of symmetrical alkane having an even number of carbon atoms. Alkanes formula, definition, structure, properties, videos. Choose from 500 different sets of substitution reaction alkanes flashcards on quizlet.
This section deals with wurtz reaction,frankland reaction. Differences in niso ratio between labelled and nonlabelled products. Since alkanes are the major components of petroleum and. For alkenes, alkynes and aromatic hydrocarbons, spring models can be constructed. Alkenes, alkynes, and aromatic compounds hydrocarbons with multiple bonds.
Iodine doesnt react with the alkanes to any extent at least, under normal lab conditions. Alkanes and alkenes organic chemistry wyzant resources. However, ignoring financial considerations, alkanes can be prepared from. Radical reactions remember that reactions are controlled by the. Preparations include the dehydration of alcohols, the dehydrohalogenation of alkyl halides, and the dehalogenation of alkanes. They are both hydrocarbons and therefore follow the. Reactions of alkanes introduction to chemistry lumen learning. Jul 30, 2014 6th in a series of 15 films covering the sl organic topic in the ib diploma chemistry course. Introduction of a halogen into a molecule chlorination, bromination general reaction. Alkanes chemical nomenclature assigns compounds a unique name that allows them to be easily identified and structurally understood. Thus, the typical reactions of alkanes a1 substitution reactions. For making models of alkanes, you can use toothpicks for bonds and plasticine balls for atoms. In substitution reactions, a hydrogen of a hydrocarbon. The alkanes and cycloalkanes, with the exception of cyclopropane, are probably the least chemically reactive class of organic compounds.
The letter in brackets, x, designates the type of reaction mechanism. Alkanes are organic compounds that consist of singlebonded carbon and hydrogen atoms. To work out the best way to distinguish alkanes from alkenes. In wourtz reaction a solution of alkyl halide in ether on heating with sodium gives alkane. However, they undergo the following reactions under certain conditions.
In general, alkanes do not react with many reagents. Chemical reactions of alkanes chemistry assignment. Hence, alkanes are quit less reactive and are known as paraffins parumlittle affinisreactivity or affinity. Reactions of alkanes 8 alkanes are generally considered unreactive as they have no functional groups present. When atomic orbitals combine to form molecular orbitals, the number of molecular orbitals that result. Organic chemistry university of california riverside. To me it appears like a primeval tropical forest full of the most remarkable things, a dreadful endless jungle into which one does not dare enter, for there seems to be no way out. If two structures just differ in the way the atoms are shown on the page, but not in the arrangement of the bonds, the molecules are the. Learn the important physical and chemical properties of the alkanes.
They will react readily with br 2 or cl 2, and ultraviolet light is not needed for the reaction. Alkanes and cycloalkanes section 2 of organic chemistry notes is 18 pages in length page 21 through page 218 and covers all youll need to know about the following lecturebook topics section 2 the nature of organic compounds. However, all saturated hydrocarbons are attacked by oxygen at ele vated temperatures and, if oxygen is in excess, complete combustion to carbon dioxide and. The cyclopropanation reaction of an alkene with a carbene takes place in a single step.
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