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Topic: Cis-alkene

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Laboration 4: Alkene isomers In most cases, there is a difference in the stability between cis- and trans-isomers of alkenes. -bond, a 1,2-disubstituted alkene can exist in two different isomeric forms, namely cis and trans. This is due to the fact that much more energy is needed to rotate a C=C bond than a C-C bond, and thus, the cis- and trans-isomers of an alkane can not equilibrate. www.oc.chalmers.se /spartanc/lab4.html   (166 words)

Markovnikov's Rule - HX + Alkene - Organic Chem 354 - Dr. Sundin - UWP Markovnikov's Rule- HX + Alkene - Organic Chem 354 - Dr. Sundin - UWP ALKYL GROUPS STABILIZE AN ALKENE MORE THAN A HYDROGEN DOES. THE TRANS STEREOISOMER IS MORE STABLE THAN THE CIS STEREOISOMER SINCE THE TRANS DOES NOT HAVE THE STERIC INTERFERENCE (STRAIN) THAT THE CIS DOES! www.uwplatt.edu /~sundin/354-7/l547-13.htm   (166 words)

Stereoisomers As a result, certain disubstituted alkenes may exist as a pair of configurational stereoisomers, often designated cis and trans. Unlike the relatively flat molecules of alkenes, substituted cycloalkanes must be viewed as three-dimensional configurations in order to appreciate the spatial orientations of the substituents. This is similar to the substitution pattern that gives rise to stereoisomers in alkenes; indeed, one might view a double bond as a two-membered ring. www.cem.msu.edu /~reusch/VirtualText/sterisom.htm   (2179 words)

Chapter 5 Notes an alkene can have cis-trans isomers only when each C in the double bond is attached to 2 different groups parent alkene is the longest continuous carbon chain that includes the double bond C=C double bond is one sigma bond and one pi bond chem.pdx.edu /~wamserc/C334F99/5notes.htm   (186 words)

CFCC Organic Chemistry Alkenes Video Lectures by Claude Wintner (Require RealPlayer): Reduction of Alkenes - Forms of Writing Reactions (video, related text) Oxidation of Alkenes to Oxiranes (Epoxides) (video, related text) Oxidation of Alkenes to 1,2-Diols (Cis-Oxidation) (video, related text) Hydration of Alkenes with Mercury (II) Acetate 1 2 Alkene Nomenclature Primer, Penn. State U. Alkene Nomenclature Quiz www.tfn.net /~pendarr/alkenes.html   (320 words)

Glossary for Web Pages Steric strain is responsible for the greater stability of trans versus cis alkenes and for the greater stability of equatorially substituted versus axially substituted cyclohexanes. Addition of water to a molecule, such as occurs when alkenes are treated with aqueous sulfuric acid to give alcohols. In the addition of HX to an alkene, the hydrogen atom bonds to the alkene carbon that has fewer alkyl substituents. www.personal.psu.edu /faculty/t/h/the1/glossary.htm   (320 words)

Regio- and Stereoselective Synthesis of (E)-Alkene trans-Xaa-Pro Dipeptide Mimetics Utilizing Organocopper-Mediated Anti-SN2' Reactions Among such motifs are alkene dipeptide isosteres which mimic cis- or trans-imide using (Z)- or (E)-alkene, respectively. In this report, the first regio- and stereoselective syntheses of (E)-alkene dipeptide isosteres (20, 31, and 35) corresponding to trans-proline dipeptides are described. Proline dipeptides (Xaa-Pro) exist as an equilibrium mixture of cis- and trans-rotamers, which depends on the energy barriers for imide isomerization. pubs.acs.org /cgi-bin/abstract.cgi/joceah/2002/67/i17/abs/jo025922u.html   (342 words)

Help The molecule shown has 2 degrees of unsaturation, the methyl groups are cis (Z), and is not an alkene nor an alkyne. The molecule shown has 3 degrees of unsaturation, the cyano and ethyl groups are cis (Z), and the molecule is neither an alkene nor an alkyne. The molecule shown has 2 degrees of unsaturation, there is no E,Z stereochemistry and is neither an alkene nor an alkyne. www.chem.uic.edu /web1/ocol/Q2/Q2-3h.htm   (336 words)

VOH // Questions and Answers for 10D Thus, reaction of an alkyne with hydrogen (even a large excess), in the presence of a poisoned catalyst (such as Pt/C with quinoline) will give cis-alkene; no alkane is formed. About quinoline and catalytic hydrogenation: Reaction of an alkynes with hydrogen in the presence of a catalyst such as Pt/C gives a cis-alkene. The purpose of the Wittig reaction is to convert an aldehyde or ketone into an alkene. voh.chem.ucla.edu /vohtar/winter98/10D/qa.html   (336 words)

Diels-Alder Mechanism In solution, the carbon-carbon single bond in the diene that connects the two alkenes is constantly rotating, so at equilibrium there is usually some mixture of dienes in the s-trans conformation and some in the s-cis conformation. Because of the Diels-Alder's requirement for having the diene in a s-cis conformation, dienes in rings react particularly rapidly because they are "locked" in the s-cis conformation. One quirk of the Diels-Alder reaction is that the diene is required to be in the s-cis conformation in order for the Diels-Alder reaction to work. www.chemhelper.com /dielsalder.html   (520 words)

Chemoenzymatic synthesis of enantiopure dihydroxy-1,2,3,4-tetrahydronaphthalenes The isolated monols 5 (from alkene 3), 7 and 8 (from alkene 6), are among the first members of the arene hydrate family of metabolites to have been isolated. This report describes the synthesis of all possible enantiopure diols of 1,2,3,4-tetrahydronaphthalene, starting from the readily available metabolites cis -dihydrodiol (2) and arene hydrate (5) and from the meso cis -diol (9). The enantiopure (1 R,2 S) dihydrodiol 2 and (1 R) arene hydrate 5 derivatives, readily available from biotransformation of naphthalene 1 and 1,2-dihydronaphthalene 3 respectively, have been used as precursors of  chiral 1,2,3,4-tetrahydronaphthalene diols 4, 13, 18, 21, 26 and 31. www.arkat-usa.org /ark/journal/2003/I07_McKervey/AM-707D/707D.asp   (520 words)

Essentials of General, Organic, and Biological Chemistry Because rotation about a carbon - carbon double bond is restricted, some alkenes exist in two isomeric (cis - trans) forms. When both the alkene and the reactant are unsymmetrical, the addition proceeds according to Markovnikov's rule: The carbon atom of the double bond that already has the greater number of H atoms gets one more. Cis - trans isomerism is possible when each carbon of the double bond is attached to two different groups. college.hmco.com /chemistry/gob/stoker/essentials_gob/1e/students/protected/concepts/ch11.html   (385 words)

Addition Problem 2 - Mechanism Lindlar's catalyst is a specialized catalyst and is only used in the hydrogentaion of an alkyne to form a cis alkene. The hydrogenation of an alkyne using Lindlar's catalyst results in the formation of the cis alkene only. Lindlar's catalyst is a palladium on calcium carbonate combination to which lead acetate and quinoline have been added. csm.jmu.edu /chemistry/courses/chem341/practice/reactions/addition/reactant02/mechanism.htm   (122 words)

OCOL This will rapidly convert to the more stable "chair" conformation, placing (for the diene) the methyl groups of the diene 1,4-equatorial-axial, or cis- relative to each other (trans-trans yields cis-), and the methyl groups of the dienophile 1,2-diequatorial or trans- relative to each other (trans-dienophile yields trans-product). The cis-trans diene will react with the dienophile to give a cyclohexene in an approximate "boat" conformation. In a [4+2] cycloaddition reaction, new bonds will form between the terminal carbons of the diene and the alkene carbons of the dienophile, as shown below, to give the substituted cyclohexene product. chipo.chem.uic.edu /web1/OCOL3/CH14/15A/SMILES.HTM   (122 words)

114rall.htm Be able to tell whether an alkene is a cis or trans isomer, or neither. Be able to define: alkane, R-group, isomer, combustion, functional group, empirical formula, molecular formula, structural formula, condensed formula, line formula, hydrocarbon, alkane, alkene, alkyne, alkyl halide, cycloalkane, IUPAC, primary carbon, secondary carbon, tertiary, quaternary carbon Be able to list the thiol functional group and remember for biochemistry that disulfide bonds can and do form. www.fhsu.edu /chemistry/twiese/114/114rall.htm   (122 words)

Pericyclic Reaction Chemistry The 1,3,5-cyclononatriene now has two cis and one trans double bonds, however, the nine membered ring is able to accommodate the strain of a trans alkene. This thermal and photo selectivity can be exploited in the reaction sequence below in which 1,3,5-cyclononatriene is converted into bicyclic systems with first cis and then trans ring junctions. This is thermally ring closed in a disrotatory manner and then photo-ring opened at -20°C in a conrotatory manner. www.meta-synthesis.com /webbook/49_pericyclic/pericyclic.html   (122 words)

varela.doc Thus, the hydroboration of tetrasubstituted alkenes and, in particular, bicyclic alkenes with BH3·THF at 50 °C provides, via a highly stereoselective 1,2-rearrangement and a remote C-H activation, a diol in which the relative stereochemistry of up to three centers has been controlled. We have therefore prepared the trisubstituted alkene 16 and were pleased to find that the hydroboration of 16 with BH3·THF and subsequent heating of 16 in THF at 50 °C for 24 h furnished, after oxidative work-up, the diastereomerically pure diol 17 in 60 % yield (Scheme 3). Although the 1,2-migration process of 9 to 12 should readily occur under the reaction conditions, the observed diastereoselectivity of the C-H rearrangement is difficult to explain (cis-arrangement of the substituents in 5). www.mariecurie.org /annals/volume2/varela.doc   (122 words)

Diels-Alder Mechanism Since the dienophile is cis disubstituted, you get the endo stereochemistry with the two cyano (CN) substituents pointing away from the top of the bicyclo compound. One quirk of the Diels-Alder reaction is that the diene is required to be in the s-cis conformation in order for the Diels-Alder reaction to work. The Diels-Alder reaction combines a diene (a molecule with two alternating double bonds) and a dienophile (an alkene) to make rings and bicyclic compounds. www.chemhelper.com /dielsalder.html   (122 words)

Student Doctor Network Forums - OC Question...Alkyne Reduction Schaum's states that the reduction of an alkyne with Lindlar's catalyst (H2/Pd) results in a cis-alkene. Catalytic hydrogenation is H2/Pd,Ni,Pt and they will reduce both an alkyne and an alkene to an alkane...so alkane is the answer to your question. However, it is important to recognize that H2 addition is a syn addition (it could affect the stereochemistry in your answer). forums.studentdoctor.net /showthread.php?t=174146   (1024 words)

Kalamazoo Valley Community College! functional group, alkane, alkene, alkyne, arene, halide, alcohol, ether, amine, nitrile, nitro, sulfide, sulfoxide, sulfone, thiol, carbonyl, aldehyde, ketone, acid, ester, amide, acid chloride, acid anhydride, hydrocarbon, saturated, aliphatic, straight chain, branched chain, normal alkane, isomer, constitutional isomer, alkyl group, IUPAC, paraffin, cycloalkane, alicyclic, cis, trans, stereoisomer. Identify and draw cis and trans isomers for substituted alicyclic compounds. Identify and name the degree of alkyl substitution for carbons and hydrogens in organic molecules. puma.kvcc.edu /rmargelis/Chm220Outlines/chapter3.htm   (1024 words)

Oz The conversion of an alkene to an ozonide is a 6-electron oxidation yet the oxidation of an alkene to two carbonyl compounds is a 4-electron oxidation. , the zwitterions 6 and 7 undergo cycloaddition reactions with the carbonyl compounds 5 and 8 to form ozonides 9, 10 and 11, each of which can exist as a pair of diastereomers (cis/trans). The two electron reduction of the O-O bond of the ozonide is often accomplished with zinc or dimethyl sulfide. classes.yale.edu /chem220a/studyaids/ozonolysis/Oz.html   (1192 words)

CHEM 331, Organic Chemistry I When the total number of substituents is 3 or 4, the isomers are classified as E or Z by assigning the order of priority of subsituents at each carbon of the double bond and giving an E designation to an alkene with the high priority substituents in a trans- configuration. If the total number of different substituents on a double bond is 2, geometric isomers may be classified as cis- or trans-. This leads to existence of (achiral) geometric isomers with a different arrangement of substituents around a double bond. www.towson.edu /~ryzhkov/handouts/stereo.html   (826 words)

UCCS Chem 330 Fall- Objectives for Exam 1 Given a structure provide the IUPAC name, or given an IUPAC or common name draw the structure, for any alkene or alkyne, including cis-trans and E-Z designations where appropriate. Given a structure provide the IUPAC name, or given an IUPAC name, draw the structure, of any carboxylic acid ester, amide, acid halide or anhydride. Given a structure provide the IUPAC name, or given an IUPAC name, draw the structure, of simple carboxylic acids and dicarboxylic acids. www.uccs.edu /~amschoff/chem330/330objsfinal.html   (801 words)

OVERALL COURSE REVIEW Isomers (cis/trans) CIP sequence rules as applied to nomenclature How does the heat of hydrogenation of an alkene relate to its stability relative to isomeric alkenes? How can the exact percentages of any two isomers at equilibrium be calculated if the energy difference between the two isomers is known? www.dartmouth.edu /~chem51/overall/overall.html   (3913 words)

30 As with carbon-carbon double bonds, carbon-carbon triple bonds are not free to rotate, but the concept of cis-trans isomers about a triple bond does not make sense. The parent chain in an alkyl substituted alkene is the longest chain that contains the double bond. This is not the case, the c-c double bonds are all the same length in benzene. darkwing.uoregon.edu /~ch111/L30.htm   (3913 words)

30 As with carbon-carbon double bonds, carbon-carbon triple bonds are not free to rotate, but the concept of cis-trans isomers about a triple bond does not make sense. Because of the special bonding in benzene, it is not classified as an alkene and it is much less reactive than most alkenes. The pi-bonding electrons (see a picture of the pi-bonding in benzene) in benzene are said to be delocalized and it is this delocalization that gives benzene and related compounds their low chemical reactivity. darkwing.uoregon.edu /~ch111/L30.htm   (3913 words)

Chapter 25, Section 3 The location of the double bond along an alkene chain is indicated by a prefix number that designates the number of the carbon atom that is part of the double bond and is nearest an end of the chain. Finally we note that the geometrical configuration at the double bond is cis; that is, the alkyl groups are bonded to the double bond on the same side. The double bond begins at carbon 2 (numbering from the end closest to the double bond); thus the parent hydrocarbon chain is named 2-heptene. cwx.prenhall.com /bookbind/pubbooks/blb/chapter25/medialib/blb2503.html   (1495 words)

ORGANIC CHEMISTRY I - CHAPTER 6 LECTURE OUTLINE Use of cis and trans in the nomenclature usually limited to disubstituted alkenes (alkenes where the double bonds have one hydrogen on each of the double bond carbons). Upon examining hydrogen halide (HX) addition to alkenes, Markovnikov's Rule was proposed: In the addition of HX to an alkene, the H attaches to the carbon of the double bond with the fewest alkyl substituents (i.e., most H's) and the X attaches to the carbon with the most alkyl substituents. For cycloalkenes, number the ring so that the double bond carbons are C-1 and C-2 and so that the branches get the lowest number possible. www.sbuniv.edu /~ggray/CHE3304/ocp6outl.html   (643 words)

lecturenotes3.html Since the double bond is not free to rotate, when the two carbons have two different substituent groups attached to them, the isomers termed cis and trans are formed. The family ALKENE contains molecules which contain at least one carbon-carbon double bond. The carbon-carbon triple bond is not free to rotate, the bond angles are 180 degrees and the shape of the molecule is linear. www.clas.ufl.edu /users/tmullins/BCH3023/fall98/lecturenotes3.html   (524 words)

CHEM 331, Organic Chemistry I When the total number of substituents is 3 or 4, the isomers are classified as E or Z by assigning the order of priority of subsituents at each carbon of the double bond and giving an E designation to an alkene with the high priority substituents in a trans- configuration. If the total number of different substituents on a double bond is 2, geometric isomers may be classified as cis- or trans-. CONFORMATIONAL ENANTIOMERS: Enantiomers that are interconvertable by internal inversion or by rotation around C-C bond when the barrier to these processes is low. www.towson.edu /~ryzhkov/handouts/stereo.html   (524 words)

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