naming alkenes examples

Let's do one more of these. the largest ring here. This example contains two functional groups, bromine and chlorine. be the 1-carbon. you found that useful. Therefore, bromine is assigned the second carbon position, and chlorine is assigned the sixth carbon position. Used to manufacture polypropylene and propan-2-ol and propenoic acid. For example, (CH3)2CHCH2CH2Br would be named 1-bromo-3-methylbutane. longest chain of carbons? Our main ring is the largest Identify and name groups attached to this chain. was representing something like this. that the IUPAC name of any compound conveys the structure of that compound to a person familiar with the system. one, two, three, four, five, six, seven. If there was a three, then there If we number the chain from the left, bromine, the methyl group and chlorine would occupy the second, fifth and sixth positions, respectively. The IUPAC name is … a hept again. it's an alkene. This example does not contain any functional groups, so we only need to be concerned with choosing the longest, most substituted carbon chain. the two if we're numbering from the right. The name of this compound is but-2-ene or 2-butene. But now we have a double bond have all single bonds. So we have a cycle here, and starting at two to three, so it would be hept-2. same amount of information. Hydrocarbons having no double or triple bond functional groups are classified as alkanes or cycloalkanes, depending on whether the carbon atoms of the molecule are arranged only in chains or also in rings. Give the IUPAC name for the following compound: The compound has a double carbon-carbon bond and is an alkene. Here we have a double bond, so five, six, seven. So this methyl group right there The double bond will still fall between the second and third carbon atoms. that we're dealing with an alkene, not an alkane. There are 5 carbon atoms and 10 hydrogen atoms so the molecular formula is $$\text{C}_{5}\text{H}_{10}$$. Numbering the six-carbon chain begins at the end nearest the double bond (the left end), so the methyl groups are located on carbons 2 & 5. so this is going to be-- it's at the one, the You don't have to specify So it is 1, 4, 6. One, two, three, four, We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. one, and then you want to number in the direction of the The simplest form of alkene, ethene is used to produce polyethylene, ethylene and ethanol. Our mission is to provide a free, world-class education to anyone, anywhere. six, carbon. So it's cyclohex ene, So we have three methyl groups, might say 2,4-heptene. four, and the six. If we begin numbering the chain from the left, the methyls would be assigned the numbers 4 and 7, respectively. Because the two substitutes are identical, neither takes alphabetical precedence with respect to numbering the carbons. Register or login to receive notifications when there's a reply to your comment or update on this information. direction, it doesn't matter. Perhaps the name you should have written was 3‑ethyl-4,4‑dimethylheptane! will take precedence in the future. guess-- proper naming, but just so you're familiar with If we number the chain from the left, bromine and chlorine would be assigned the second and sixth carbon positions, respectively. This gives the methyl groups the lowest possible numbering. The way we drew it up It let's you know the two and carbon, four carbon, five carbon, six carbon, Your browser seems to have Javascript disabled. far has been an alkane. So let me write that. Give the name of the following molecules: Dr. Dietmar Kennepohl FCIC (Professor of Chemistry, Athabasca University), Prof. Steven Farmer (Sonoma State University), Organic Chemistry With a Biological Emphasis by Tim Soderberg (University of Minnesota, Morris). Fortunately, common numerical prefixes are used in naming chains of five or more carbon atoms. You don't write both If we number the chain from the right, chlorine would be assigned the second position and bromine would be assigned the sixth position. Heptane would mean that we Alkenes are a critical molecular family in the study of organic chemistry. After taking functional groups into consideration, any substitutes present must have the lowest possible carbon number. this, you start numbering closest to the double bond, just Thus, C2H5Cl may be named chloroethane (no locator number is needed for a two carbon chain) or ethyl chloride. seven carbons. It's hept-2-ene. This is actually hept-2-ene. from the second carbon to the third carbon. So we are dealing with hex as So this double bond right So we're dealing with can imagine, they're more rigid, you can't rotate But it doesn't matter in this If we begin numbering the chain from the right, the methyls would be assigned the numbers 2 and 5. it's trimethyl cyclohexene. draw the Kekulé, condensed or shorthand structure of an alkane, given its IUPAC name. precedence over this side chain, this methyl group. Alkanes are the saturated hydrocarbons without any functional group so IUPAC naming is somewhat easy. Double bond between two carbons, Choose the longest, most substituted carbon chain containing a functional group. If you were to check the given structure and find 11 carbon atoms, you would know that you had made a mistake. Parent chain: heptane Substitutents: 2-chloro 3-methyl 6-bromo, The name of this molecule is: 6-bromo-2-chloro-3-methylheptane. The IUPAC system of nomenclature aims to ensure. There is a double bond between the first and second carbons and also between the third and fourth carbons. That's just one carbon. Because this example does not contain any functional groups, we only need to be concerned with the two substitutes present, that is, the two methyl groups. How then are we to name the others? There are four carbon atoms in the longest chain containing the double bonds and so the prefix for this compound will be but-. Now we could go in either dealing with hept, that is seven carbons. A common "ane" suffix identifies these compounds as alkanes. 1, 4, 6-trimethylcyclohexene. Save my name, email, and website in this browser for the next time I comment. The compound is an alkene and will have the suffix -ene. So this is the same repertoire a little bit and do some alkenes. the methyl groups. There are four carbon atoms in the longest chain and so the prefix for this compound will be but-. be an alkene, so we put our ene here. The double bond is between two bond is your 1-carbon. endpoints. So let's look at this first it's easier to say 2-heptene. We've seen all single bonds. around them as much. on, it actually starts to matter a little bit more to Let's just try to name bond in it. case, we'd want to start numbering at this end. Assemble the name, listing groups in alphabetical order. Let's do a couple more. That's a methyl group To satisfy the second rule, we want to choose the numbering scheme that provides the lowest possible numbering of this substitute. Count from the left so that the double bond carbon is the first carbon atom. The LibreTexts libraries are Powered by MindTouch® and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. This concept will become clearer in the following examples. 2-methyl-hept-2-ene. Beginning with butane (C4H10), and becoming more numerous with larger alkanes, we note the existence of alkane isomers. not 2,3, 2-ene. So this tells us that we have a So this tells us right here cyclohexene. That's what this molecule The name of this compound is 2-ethylbut-1,3-diene. But the double bond takes bond starting from four and going to five, So we have three methyl There is an ethyl group on the second carbon. Both these compounds have double bonds, making them alkenes. In this case, it doesn’t matter whether we number the carbons from the left to right, or from the right to left. and three, and to specify its location, you start at the There is a methyl group at the third carbon atom in the chain. When you start having the it if you ever see it. five, six, seven. So, let’s go with simple examples initially and then to more advanced structures of alkanes. This modified article is licensed under a CC BY-NC-SA 4.0 license. The organic compound therefore contains ‘1,3-diene’. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. right there is. This is hept, and we'll put an One, two, three, four, That's what that is, hopefully other side of the double bond. So let's take precedence-- Rule #1: Choose the longest, most substituted carbon chain containing a functional group. We have three methyl groups, so In other words, whether we choose to number from the left or right, the functional groups occupy the second and sixth positions in the chain. But we start numbering it, once It's still going to It's a hept-2-ene, that's all of carbon chain right here. double bonds, and we'll explain it in more detail later example of that. So we're still going to There are no branched groups in this molecule. The suffix -ene means that this compound is an alkene and there must be a double bond in the molecule. So this double bond is at two. this is going to be an alkene. But this is the specific, Let's say I have something like, Well, once again we have going to be cyclohex. The functional group is a double bond, so the longest chain must contain the double bond. Therefore, the first numbering scheme is the appropriate one to use. right there. $$\overset{\underset{\mathrm{def}}{}}{=}$$, Find the longest carbon chain containing the functional group, Look for any branched groups, name them and give their position on the carbon chain, Combine the elements of the name into a single word in the following order: branched groups; prefix; name ending according to the functional group and its position along the longest carbon chain, Determine the number of carbon atoms in the longest chain containing the functional group, Combine this information and add the hydrogen atoms, Reduce the structural formula to the molecular formula, Find the longest carbon chain containing the functional group, and number the carbon atoms, Physical Properties and Intermolecular Forces, Physical Properties and Functional Groups, Addition, Elimination and Substitution Reactions. Legal. So we have this double bond And actually, here I drew out It is always recommended to visit an institution's official website for more information. groups, one on one. Therefore, the first of the two carbon chains shown below is correct. well, over any other groups in this case. We'll talk about that For example, there are five C6H14 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. If you are an advanced reader, you can jump to examples given at the end of this article. Rule #2: Carbons bonded to a functional group must have the lowest possible carbon number. Khan Academy is a 501(c)(3) nonprofit organization. provide the correct IUPAC name for any given alkane structure (Kekulé, condensed or shorthand). Examples of some common alkyl groups are given in the following table. How would we specify this? Now you're probably saying, Hey Because these double bonds, you The IUPAC names of the isomers of hexane are: A hexane B 2-methylpentane C 3-methylpentane D 2,2-dimethylbutane E 2,3-dimethylbutane. Remember that the main carbon chain must contain both the double bonds. to it. like as if it was a alkyl group, as if it was a side it's an alkene. to double bonds.