What is Alkene: Definition and 27 Discussions

In chemistry, an alkene is a hydrocarbon that contains a carbon–carbon double bond.Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds. Two general types of monoalkenes are distinguished: terminal and internal. Also called α-olefins, terminal alkenes are more useful.
However, the IUPAC recommends using the name "alkene" only for acyclic hydrocarbons with just one double bond; alkadiene, alkatriene, etc., or polyene for acyclic hydrocarbons with two or more double bonds; cycloalkene, cycloalkadiene, etc. for cyclic ones; and "olefin" for the general class — cyclic or acyclic, with 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 CnH2n with n being 2 or more (which is two hydrogens less than the corresponding alkane). When n is four or more, isomers are possible, distinguished by the position and conformation of the double bond.
Alkenes are generally colorless apolar compounds, somewhat similar to alkanes but more reactive. The first few members of the series are gases or liquids at room temperature. The simplest alkene, ethylene (C2H4) (or "ethene" in the IUPAC nomenclature) is the organic compound produced on the largest scale industrially.Aromatic compounds are often drawn as cyclic alkenes, but their structure and properties are sufficiently distinct that they are not classified as alkenes or olefins. Hydrocarbons with two overlapping double bonds (C=C=C) are called allenes—the simplest such compound is itself called allene—and those with three or more overlapping bonds (C=C=C=C, C=C=C=C=C, etc.) are called cumulenes. Some authors do not consider allenes and cumulenes to be "alkenes".

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  1. Muhammad Danish

    Organic Chemistry, Hydrocarbons

    Homework Statement Homework EquationsThe Attempt at a Solution C=C double bonds means that it is not an Alkane because an Alkane is saturated hydrocarbon. So the answer should be from A, B or C.
  2. Mike Dacre

    NBS vs radical HBr in the bromination of olefins

    I am having some trouble understanding why different sources of bromine radicals supposedly brominate an alkene at different positions. What I mean by this: In the first example, the Bromine radical attacks a hydrogen at the allylic position and then a termination reaction results in a Bromine...
  3. Clack_Attack

    Hydration of Alkenes: Need for Acid

    One of the first addition reactions we learn in a basic organic chemistry class is the hydration of an alkene, that is breaking a double bond by adding water (the H and the OH specifically) across the double bond. The only requirement is that the solution be acidic. I'm wondering if the...
  4. M

    Are Alkene Diastereomers Formed Equally in Carbocation Reactions?

    Hey, so I did a lab on alkene Diastereomers ( I saw a similar thread but it wasn't really helpful... However I am guessing the same lab as me). We initially had Maleic acid and dissolved it in hot water and mixed it with hydrochloric acid ( carbocation?).The question isn't so clear ( to me...
  5. D

    Product of hydrolysis of alkene

    Homework Statement when compund P ( CH2=CHCH2CH3) and Q ( CH3CH=CHCH3) is reacted with steam , compound T which is optically active formed. draw the structure of T . the ans is on the left. my ans is on the right. is my ans ( on the right) accepted , why and why not? Homework Equations...
  6. D

    Bromination of Alkene: Trans or Cis?

    Homework Statement for the bromination of alkene, different sources give different structure of product which is trans(from wikipedia) , but the book is cis. which is correct? Homework Equations The Attempt at a Solution please don't delete my question.. as i really don't know...
  7. K

    Why does the + sign move to O in the addition of alkene with water?

    Homework Statement my question is at part 2 , since c form ch3ch2 is electron deficient, but after OH2 added in , with lone pair electron on O, the c should be no longer electron deficient anymore. am i right? why the + sign is moved to O now? Homework Equations The Attempt at a...
  8. R

    Effect of a Lindlar catalyst on an alkene?

    I know a Lindlar catalyst will cause syn addition of hydrogens to an alkyne and then stop at an alkene, but what about a molecule that has both an alkyne and an alkene in it to start. Is the alkene taken to an alkane or is it simply not affected? Thanks for your answers.
  9. G

    Alkene Nomenclature: Question 1 - Genius Attempt!

    1. I made up this problem myself in order to practice. I stumped myself. I'm such a genius, I'm aware It's basically alkene nomenclature with the E,Z naming scheme.2. Picture See below. I've taken the liberty of already numbering the longest chain.The Attempt at a Solution Without the double...
  10. S

    Ester linkage and alkene cracking

    in an ester is the ester link/bond the -COO-? meaning does it include the C=O in the ester linkage. i would think so as something else would mean the functional group is different. However, i am not entirely sure as my textbook just brakets the C-O as the ester bond. Also, can alkenes such...
  11. M

    Bromination of an alkene using isopropanol

    What would be the product if I carried out a bromination of an alkene using isopropanol as the solvent?
  12. M

    Bromination of an alkene

    I am asked for the "actual products" of reacting Br(2) with: trans-1,2-diphenylethene and cis-1,2-diphenylethene I know their structures. And I know that each Br will attach to each side of the double bond. Are there three products for each? ...with the products being isomers?
  13. M

    Ring Expansion of 1,3-Methylcyclopentene with H-Br

    I need to react 1,3-methylcyclopentene with H-Br. Do I do a ring expansion here? What I came up with is 1-bromo-3-methylcyclohexane. Am I completely off? Is there just one major product? I would appreciate the help!
  14. A

    Formation of a cis alkane from a trans alkene

    Homework Statement Create cis-1,2-epoxy-1-phenylhexane from (E)-1-phenyl-1-hexene Homework Equations The Attempt at a Solution My teacher asked for two ways to create this and I think I've got the first. The first way was by treating (E)-1-phenyl-1-hexene with H2 and poisoned...
  15. W

    How can we convert 1-hexene to cis-3-octene using alkynes as intermediates?

    Organic: Alkene to Alkyne I am trying to do a synthesis of 2-Octyne from 1-heptene. Conversion of the triple bond to a double bond is pretty easy, but i also have to add an alkyl group, and the double bond must remain on the original triple bond location. Thus, so far thoughts: 1. remove...
  16. T

    O-Chem: Alkene Reaction with HBr and Methanol

    Homework Statement What are the two final products when cis-2-butene reacts with HBr and CH3OH? Homework Equations Reactions of Alkenes.The Attempt at a Solution I'm not sure if the HBr will attack the double bond first or if the OH on methane will take the H off HBr and create a radical...
  17. L

    Alkene vs Alkyne: Hydrocarbon Bonding

    Would a hydrocarbon with both double and triple bonds be considered just an alkyne...or both an alkene and alkyne?
  18. C

    Solving Alkene Reactions Problems for Chem Exam

    Hey I'm studying for my chem exam & I am having difficulty solving some problems. 1. 1,3cyclohexadiene + Br2= ? Here,should i treat it like a conjugated diene? Meaning that the Br molecules will have 1,2 and 1,4 additions on the diene and 2 products will be there? 2. 1,4cyclohexadiene +...
  19. A

    Q. about the Cossee-Arlman mechanism in alkene polymerization

    Starting out with TiCl4 and triethylaluminum, I understand how the triethylaluminum alkylates the TiCl4 and creates a polymeric TiCl3, but then an ethene molecule coordinates with a vacant site on the alkylated TiCl3? I thought titanium's highest oxidation state was +4?
  20. K

    Can you consider a benzene ring to also be an alkene?

    Can you consider a benzene ring to also be an alkene? As in, there are double bonds within the benzene ring.
  21. K

    Is it true you can only add H to an alkene?

    My textbook introduces the reaction of catalyzed Hydrogenation and later on in the chapter states that all reactions have the ability to proceed forward or backward, yet in the elimination reactions chapter they do not mention this reaction. So, is it true?
  22. C

    Alkene Diastereomers Lab: Theory & Results

    I did a lab on alkene diastereomers and I'm a bit confused as to what the purpose was. We reacted maleic acid with a temporary carbocation to see whether the product would be maleic acid or fumaric acid. These are alkene diastereomers of each other. My results suggested that the product was...
  23. S

    Alkene reaction with Br2 and NaCl (saturated)

    Hi all, I am studying for an exam tomorrow and can't seem to find this mechanism anywhere. I know that a Br and a Cl are added in Markovnikov fashion but I don't know which would be added first and which would go on the more substituted carbon. Any help is appreciated. Thanks
  24. S

    Convert a given alkane to any higher or lower alkene without sides rxn

    how can we convert any given alkane to any other higher or lower alkane without giving rise to any side reactions i tried to find many books but they all give wurtz,decarboxylation,kolbe synthesis but for all these steps we need to prepare their halogen deirvatives which are formed in...
  25. T

    Alkene Reactions: Help with Understanding & Memorizing

    I'm having trouble keeping all these alkene reactions straight (hydroboration, oxymercuration/demurcuration, etc.) is there a useful website or an easier way to categorize/remember which reagents go with a particular reaction? My book isn't much help. Need help!
  26. A

    Infrared spectroscopy of a cyclic alkene

    At school we extracted limonene from orange peels and we had to make an IR spectroscopy for it but I don't see anywhere how we can know the product has a ring constitution... I see a lot of information about aromatic rings but nothing for an alkene ring... Can anybody help me?
  27. maverick280857

    Seven Carbon Alkene with one Stereogenic Center

    Hi I can't figure out the structure of a seven carbon alkene that has a stereogenic center (chiral center) and is known to be optically active. The structure which comes to my mind is apparently not the one that is correct...any suggestions would be greatly appreciated. Thanks and cheers...