The general formula for alkenes with one double bond is c n h 2 n. In this process, dihydrogen gas is added to alkynes and alkenes in the present catalyst. This can also be done at a lower temperature by use of catalyst such as silica or alumina. Dealing with organic compounds in chemistry can feel overwhelming. If a hydrocarbon contains double andor triple bonds, it is known as unsaturated. He spent the next several years developing this technique and passing it on to others through university organic. When alkanes are heated to high temperatures in absence of air, mixture of saturated and unsaturated hydrocarbons is formed. Hydrocarbons with only cc single bonds are known as saturated hydrocarbons. Alkanes are a group of acyclic, saturated hydrocarbons. Alkenes, alkynes, and aromatic compounds hydrocarbons with multiple bonds. Name the parent compound using the appropriate prefix. Alkenes find many diverse applications in industry. Higher alkenes and alkynes are named by counting the number of carbons in the longest continuous chain that includes the double or triple bond and appending an ene alkene or yne alkyne suffix to the stem name of the. Therefore, to convert an alkene to an alkyne, you simply need to break the double bond.
Alkenes and alkynes can be transformed into almost any other functional group you can name. Examples of alkenes include ethene, propene, but1ene and but2ene. Jan 31, 2010 alkenes are produced from the alkanes in crude oil by a process called cracking. The boiling point of alkanes increases with increasing molecular weight, the straightchain alkanes are observed to have a higher boiling point in comparison to their structural isomers. It is postulated that when ants sting, the alkanes help the formic acid spread through the victims contact point 12.
Reactions of alkenes and alkynes introduction to chemistry. The preparations of alkynes are very similar to those of the alkenes. Carbon is unique in that it can form up to four bonds in a compound, so they can easily bond with other carbon atoms, forming long chains or rings. The liquid alkanes are good solvents for many other covalent compounds. Preparation of alkanes from unsaturated hydrocarbon. They are both hydrocarbons and therefore follow the. Hydrocarbon hydrocarbon nomenclature of alkenes and alkynes. Alkane can be prepared from alkene and alkyne through the process of hydrogenation. The rules for alkenes are similar to those used for alkanes. The cracking process is important because it turns less useful alkanes into more useful smaller ones and produces very useful alkenes like ethene, the starting material for many plastics. Compound with only single bonds unsaturated hydrocarbons. 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. Chemical properties of alkanes some more reactions.
Alkanes and alkenes organic chemistry wyzant resources. In fact, there is very little difference between the two. Identify the longest continuous chain of carbon atoms that contains the carbon. Physical properties of alkanes alkanes are nonpolar only dispersion forces act between molecules. Using a flowsheet showing different reactions of alkanes, alkenes, and alkynes to solve an organic synthesis problem. Polymerization of alkenes is a reaction that yields polymers of high industrial value at great economy, such as the plastics polyethylene and polypropylene. Compound composed of only carbon and hydrogen saturated hydrocarbons. In particular, these molecules can participate in a variety of addition reactions and can be used in polymer formation.
They are called saturated hydrocarbons because there is a hydrogen in every possible location, and are used as the basis for naming the majority of organic compounds. We just need to break open the double bond and attach an h to each of the carbons. Melting points of alkenes are higher than alkanes because p electrons of double bond are polarizable. Each video lesson provides an easy, yet comprehensive approach made from the student. Hydrogenation of alkenes and dehydrogenation of alkanes. The physical properties of alkenes are similar to those of the alkanes. By contrast, alkenes, olefins, have two hydrogens less than the saturated formula, i. Polymers from alkene monomers are referred to in a general way as polyolefins or in rare instances as polyalkenes.
As a result, intermolecular forces of attraction are stronger. Alkanes formula, definition, structure, properties, videos. Click here to see how our chapters match up with your schooltextbook. What follows applies equally to alkanes and cycloalkanes. In these compounds, unsaturation is due to the presence of the double bond. Naming alkenes and alkynes rules are almost identical to naming for alkanes step 1. Each video lesson provides an easy, yet comprehensive approach made from the student perspective. Briefly identify the important distinctions between an alkene and an alkane. Alkenes have the general formula n cx nhx 2n, where n is the number of carbon atoms in the molecule. A small difference in the molecule changes the name and can drastically change the reactivity of the compound. Alkenes can be straight chain, branched chain, or cyclic.
Preparation of alkanes from carboxylic acids, alkyl halides. When the chain is longer than 3 carbons, number the atoms such that the double bond is given the lowest number. Alkanes are useful as fuels and alkenes are used to make chemicals such as plastic. Crackochem chapters match up with any textbook you use, but may be in a different order. In the molecular mass but they do not show any regular trend. The melting point of alkanes follow the same trend as their boiling point that is, it increases with increase in molecular weight. While alkanes and alkenes are both hydrocarbons, the primary difference is that alkanes are saturated molecules, containing only single covalent bonds. An alkane, on the other hand, is a hydrocarbon with only single bonds. Hydrocarbons, alkanes, electrophilic addition reactions, electrophilic attack, stability of carbocation. This catalysts which are finely divided is like nickel, palladium or platinum to form alkanes. Plus great graphics to understand everything better. Cracking uses heat and a catalyst to decompose alkanes. Hydrocarbon nomenclature of alkenes and alkynes britannica.
Powerpoint and afl task for teaching alkanes and alkenes. Alkenes and alkynes are generally more reactive than alkanes due to the electron density available in their pi bonds. We turn next to reactions in which a hydrogen molecule is added to the double bond of an alkene, forming an alkane and the reverse, in which. This holds true for the two compound groups, alkanes and alkenes. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The main preparative reactions involve the elimination of groups or ions from molecules, resulting in the formation of.
Find the longest chain containing the double alkene or triple bond alkyne name the parent compound by adding the suffix ene alkene or yne alkyne. Apr 23, 2011 in this video, we begin our transition from general chemistry into the exciting world of organic chemistry. Alkanes are virtually insoluble in water, but dissolve in organic solvents. Alkenes are the unsaturated hydrocarbons in which there is a double bond between two carbon atoms. Alkenes and alkynes organic chemistry science khan academy. The naming conventions for these compounds are similar to those for alkanes. Let crackochem be your personal organic chemistry video tutor. Crackochem videos are set up to match book chapters in any order. Alkenes and alkynes boundless chemistry lumen learning. Organic chemistry is the study of carbon compounds, so the study of organic chemistry is important because all living things are based on carbon compounds.
Hydrocarbons are organic compounds which only consist of carbon c and hydrogen h as their elements. When a molecular substance dissolves in water, you have to. In the absence of a spark or a highintensity light source, alkanes are generally inert to chemical reactions. Cracking of alkanes cracking is a form of thermal decomposition, which breaks long chain hydrocarbons, many of which are not very useful, into shorter molecules by heating them. Alkanes, alkenes and alkynes a hydrocarbon that contains no double bonds is called an alkane, or hydrocarbon containing only single bonds. Compounds with at least one double or triple bond 2.
The most important alkenes for the chemical industry are ethene, propene and 1,3butadiene. Ethylene and acetylene are synonyms in the iupac nomenclature system for ethene and ethyne, respectively. They are used as starting materials in the syntheses of alcohols, plastics, laquers, detergents, and fuels. Because these videos are so comprehensive, some students have successfully. It is quite important that you can write properly balanced equations for these reactions, because they often come up as a part of thermochemistry calculations. Simple alkenes often have common names, but all alkenes can be named by the system of the international union of pure and applied chemistry and have the ending ene. Apr 20, 2018 alkenes are also hydrocarbons, but they are unsaturated, meaning they contain carboncarbon double bonds, for example, there are one or more double bonds between carbon atoms in the molecule. Ants and cockroaches have nundecane which is a pheromone in their bodies 11. Boiling points, melting points, and densities generally increase with the size of the alkane.
563 1171 793 674 411 360 204 360 1142 154 268 106 247 481 380 1360 74 1081 740 725 535 999 584 1260 864 1143 1037 1452 549 18 1303 426 311 707 991 1392 398 663 1261 1205 1260 701 694 462 697