(a) Draw the structural formula of each of the isomers (include all atoms). Most women find that topical vitamin C brightens their complexion and takes off years of aging from their face. Is there any model that comes from QCD that explains why atomic nucleus are stable? Stack Exchange Network Stack Exchange network consists of 176 Q&A communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. The heats of formation (ΔH f o in kcal/mol) of selected alkenes are shown on the right. Hence these are called as positional isomers. (6 points) cub. The isomers of a chiral compound often differ from each other in their biological properties. It certainly has constitutional isomers: For example, the sum formula $\ce{C6H6}$ does describe benzene as well as hex-1,5-en-3-in $\ce{H2C=CH-C#C-CH=CH2}$. 1 triple bond. Using the z-rotate tool, R-drag to rotate the selection about the rotation bond. Ethene can be converted into a variety of useful products as illustrated. This kind of instability is known as ring strain, and it occurs because the most thermodynamically stable carbon-to-carbon bond angle is 109. Cyclobutane itself is of no commercial or biological significance, but more complex derivatives are important in biology and biotechnology. 1 differ by one methylene group. I'd imagine that, were the data available, that 2,2,3,3-tetramethylpentane would be still more stable. Problem: Identify the more stable stereoisomer in each of the following pairs, and give the reason for your choice: (a) cis- or trans-1-Isopropyl-2-methylcyclohexane 🤓 Based on our data, we think this question is relevant for Professor Switzer's class at UCR. Experiment 1: "A cis to trans conversion" Saturday, June 25, 2005 4:19 PM Notes on Theory • Alkenes o They are hydrocarbons with a C=C double bond • Double bonds are stronger and more reactive than single bonds o Hydrocarbons with double bonds used to be known as "olefins", because they had an oily appearance • "Oleum" means oil • "Ficare" means make • Isomers o Geometric isomers. and Goulay, F. AU - Degregorio, Michael W. Isomers are different compounds with the same molecular formula. Meaning of metastable isomer. [–]anon1moosPh. For nitrito isomer, these are the stretches of N=O bond which is observed at 1480-1380 cm-1, and the stretch of the N-O group that occurs at 1200-1050 cm-1. Draw both the eclipsed and staggered conformations of 2-chloropropane in the Newman projection looking down the C1-C2 bond. In the options given below the isomer given in the option A of 1-tert-butyl-5-methylcyclohexane is the most stable of all. Let us look at the most two important. The formula is also C4H10. equal to one. (c) the bromine atom in an axial position and the chlorine atom in an equatorial position. Isomers Pentane is one of three structural isomers with the molecular formula C 5 H 12 , the others being isopentane and neopentane. The heats of formation (ΔH f o in kcal/mol) of selected alkenes are shown on the right. Coordination compounds are important for at least three reasons. 2007,,, 63-117. Isomers which differ only in shifting a hydrogen from one atom to another are often called tautomers. Ethane is a saturated molecule. Computational chemistry can be very useful for calculating the relative energies of different conformers and isomers, and determining which is most stable. 1-tert-butyl-3-methylcyclohexane c. (8 pts) Draw both the cis and trans isomer of 1-chloro-2-ethylcyclohexane (pictured), each as a pair of chair conformers. Most alkanes you will come across are relatively small molecules in which all the chemical bonds are covalent bonds. Here one isomer is an open chain molecule and the other a cyclic molecule. slowly and tend to be stable even when solvated. Theoretical calculations performed to find stationary points on the potential energy surface confirm that the observed structure is the most stable form. Basic aspects of Stereochemistry 1. Reoptimize the geometry and save the structure of the most stable conformer of each isomer. Delta H should not change, since it is simply the difference in energy between A and B. Conformations of butane. Two are cis-2-tert-butylcyclohexanol and two are cis-3-tert-butylcyclohexanol. The (E)-isomer would dominate in an equilibrium mixture because it is the most stable. C5H12 C3H6(propene) KBrO3 C3H8 AgNO3 C4H8(cyclobutane) None. The chair conformations with 2 equatorial methyls ad 1 axial methyls C. Butanol isomers A detailed chemical kinetic mechanism has been developed and validated using experimental data from shock tubes, a rapid compression machine (RCM) and a jet stirred reactor (JSR). B Two mark questions 1. The staggered conformation is the most stable as it has the lowest energy. Malleable means capable of being hammered into thin sheets. Now make models of cis and trans 1,4-dimethylcyclohexane. Furthermore, the double bond formed as the intermediate functional group was also. Benzene is the global minimum on the potential energy surface of C 6 H 6, 35 kcal mol −1 lower in energy than the second most stable isomer, fulvene. A conformer is also known as a conformational isomer. The most significant conformers of ethane are the staggered and eclipsed conformers. }, abstractNote = {We carried out the product detection studies of C(3P) atom reactions with butene (C4H8) isomers (but-1-ene, cis-but-2-ene, trans. These isomers arise because of the possibility of branching in carbon chains. For each of the four alcohols, predict the alkene product(s), including the expected major product, from an acid-catalyzed dehydration (E1) reaction. Also, internal alkenes are more stable than terminal ones. It is proposed that if each isomeric carbon cage for a given fullerene C n is constructed such that no five-membered ring contains a double bond, then the most stable isomer is that containing the highest number of benzenoid rings (i. Note that the twelve atoms that make up these isomers are connected or bonded in very different ways. Most stable cis is one axial and one equatorial (i. See the following isomers of butene: Figure 7. For example, the isomer of C 3 H 8 O that is an ether boils at -23 °C, while the two isomers that are alcohols boil at +78 °C and +83 °C. The isomerism in organic compounds can be classified broadly into: Structural isomerism (constitutional isomerism) In general the keto form is the low energy form and is more stable than the enol form. Hydrocarbon structures and types of isomerism (structural isomers, cis/trans isomers, and enantiomers). There are two characteristic stretches for both isomers which can be used to distinguish the products. 1 A brief guide to the structure and nomenclature of non-cyclic alkane hydrocarbons. WHY? The order of stability for carbocations is. Shorthand structures for four of these isomers are shown below with their IUPAC names. Chemistry Cyclopropane, C3H6, is converted to its isomer propylene, CH2=CHCH3, when heated. Both compounds exist as gases at 25°C and 1. Alkanes are simplest hydrocarbons with all C-C bonds. (Other types of reaction have been substitution and elimination). (6 points) cub. 2-Methylpropene. The ClClO2 isomer is predicted to be the most stable isomer and is more stable than ClOOCl by 3. Their structures are shown below. The main difference between alpha and beta glucose is the position of the -OH group attached to their first carbon atom. Write IUPAC name of the following [CO(NH 3) 6Cl 3 Hexaaminocobalt(III)chloride 2. Molecular Weight 156. The concentration of the nitrito isomer plotted against the time yields a line with a negative slope. Both halide atoms in equatorial positions. The energy difference between cis-and trans-cyclooctene is approximately 38. Examples include alkenes such as butene and alkanes such as cyclobutane and methylcyclopropane. The most basic five carbon chain will have a chemical formula of: C 5 H 12, but as pentene has a double bond, it has two less hydrogen atoms. How-ever, all theoretical models predict that the most stable isomer is not the all-equatorial isomer 13 but 9 which has two neighboring axial substituents. In the second isomer, however, the styrene phenyl group is oriented towards the phenylimido ligand. Fullerenes in which a high proportion of the hexagonal rings are benzenoid are very stable, e. If cyclohexane is mono-substituted with a large substituent, then the substituent will most likely be found attached in an equatorial position, as this is the slightly more stable conformation. Constitutional isomers. Rank by alkene stability. The isomer with the methyl groups on the same side is called the cis isomer, while the isomer with the groups located on opposite sides is called the trans isomer. X‐ray crystallography revealed C s ‐symmetrical molecular structures of both compounds, with the former being a substructure of the latter (see picture; C grey, Cl green). We have seen examples on this type of isomers on page 21 in the hand out you have been given before. MDL number MFCD00001472. The other shapes we have looked at, the two eclipsed conformations, are not very stable at all. equal to two:. Which of the following is the most stable conformer of the most stable isomer of 1,4-diethylcyclohexane? Ans: 71. 035a Hybrid-Meta-GGA TPSSh I 0. Which isomer is most stable and why? 2. Give the structures of these two isomers and name the type of structural isomerism shown. CH 3 H 3 C H H H H 3 C H CH 3 HH H 3 C H CH 33. Therefore the only functional group that can be present is an alkane. Problem: Which isomer of C8H18 is the most stable? 🤓 Based on our data, we think this question is relevant for Professor Daoudi's class at UCF. and Le Picard, S. A correct IUPAC name for the following compound is: A) 2,5-Dimethyl -3-propylheptane B) 3,6-Dimethyl -5-propylheptane Which isomer of C 5H10 would you expect to have the smallest heat of combustion*? A) Cyclopentane What structure represents the most stable conformation of cis-1,3-dimethylcyclohexane? H H3C H CH 3 CH3 H H H3C H CH3 H. Write down reasonable isomers for your predicted geometries and determine in each case which isomer is the most likely. In general the Keto form is more stable. This video shows you how to draw the constitutional isomers of C4H8. The Glycosidase Team: (L to R) Sergi Pascual, Aditya Pote, Antoni Planas, Mark Peczuh. Isomers of Organic Compounds, An Introduction: By: Frank R. Experiment 1: "A cis to trans conversion" Saturday, June 25, 2005 4:19 PM Notes on Theory • Alkenes o They are hydrocarbons with a C=C double bond • Double bonds are stronger and more reactive than single bonds o Hydrocarbons with double bonds used to be known as "olefins", because they had an oily appearance • "Oleum" means oil • "Ficare" means make • Isomers o Geometric isomers. The chain isomers have almost similar chemical properties but different physical properties. AP® CHEMISTRY 2010 SCORING GUIDELINES (Form B) Question 1 (10 points) The compound butane, C 4 H 10, occurs in two isomeric forms, n-butane and isobutane (2-methyl propane). Isomers are those organic compounds having the same molecular formulae but different in arrangement of an atoms of that particular molecule ( i. In the Conformational isomers we can convert from one isomer to other isomers by just rotation about C-C bonds. The less heat released, the more stable. This video shows you how to draw the constitutional isomers of C4H8. Ch08 Reacns of Alkenes (landscape) Page 1 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. It Takes AlkynesAlkynes take alkanes to the next level…all the way up to a triple bond. All carbon atoms tend to complete their tetravalency by bonding with the same or different atoms. The staggered conformation is the most stable as it has the lowest energy. in terms of cyclic alkanes. However, the cis isomer is. The most water soluble compound is 1, while the least water soluble compound is 5. Now make models of cis and trans 1,4-dimethylcyclohexane. Which isomer of C 5H10 would you A correct IUPAC name for the following compound is: What structure represents the most stable conformation of cis-1,3. 6% of the earth's crust; it is the most abundant of the alkali group of metals. Only difference in these compounds is 2-methyl propane has 3 carbon atoms in main carbon chain and there is CH3. 3 kcal/mol at 298 K. D) tert-butyl is equatorial and the methyl is equatorial. Pietropolli Charmet,2 N. 9th Edition. The isomer with the methyl groups on the same side is called the cis isomer, while the isomer with the groups located on opposite sides is called the trans isomer. In disubstituted alkenes, trans isomers are more stable than cis isomers due to steric hindrance. equilibrium between clothianidin and its Z-isomer. Post questions you can’t solve, Past exam questions with answers, large question bank. Similar relationships occur within families, for example, you can only be a brother or sister to someone else while a person. isomerism[ī′säm·ə‚riz·əm] (biology) The condition of having two or more comparable parts made up of identical numbers of similar segments. 3-Methylbut-1-ene. B Two mark questions 1. First, rather than being the center of a "funnel" in an energy landscape of isomers, penta-graphene is part of the "funnel" that leads to graphene as the most stable structure. Additional [1,2] H. It is stable but incompatible with strong oxidizing agents, strong acids and strong bases. Stability of Dibenzalacetone Isomers: In the synthesis of dibenzalacetone by aldol condensation of acetone with benzaldehyde 1 the primary product melts at 110-112° C and has a intense uv absorption at 330 nm. Theoretical calculations performed to find stationary points on the potential energy surface confirm that the observed structure is the most stable form. This hydrocarbon has two hydrogens less, so it must contain either a double bond or a ring. Rather, the two most stable isomers of the group are the branched chain isomers; tert-butylnitrile and isobutyl cyanide. 4 Hydrocarbon Rings • Some hydrocarbon compounds have a carbon chain that is in the form of a ring. Substituent Effects on Alkene Stability Electronic disubstituted alkenes are more stable than monosubstituted alkenes Steric trans alkenes are more stable than cis alkenes Figure 5. In acyclic systems, trans isomers are more stable than cis isomers. What is the F-Xe-F bond angle in the more stable isomer? E. The double bond is made up of one strong σ bond and one weak π bond. Isomers which differ only in shifting a hydrogen from one atom to another are often called tautomers. The most stable IPR isomer of C 88 fullerene, C 88 (17), has been captured by chlorination as C 88 (17)Cl 16 and C 88 (17)Cl 22. Don't forget you can E,Z (cis and trans) isomers about a C=C bond. What symmetry elements are present in the most stable form of SF4? D. The recent suggestion, based on gas-phase experimental data, that the most stable isomer of protonated benzene has a face-protonated π-complex structure is not supported by our detailed computations which indicate that the π-complex is a second-order saddle point on the potential energy surface, lying 199 kJ mo -1 higher in energy than the well-established C 2v σ-protonated structure. The most water soluble compound is 1, while the least water soluble compound is 5. cis-But-2-ene. constitutional isomers. Both 1-butene and 2-butene contain linear arrangement of carbons. The chemical bonding in alkane molecules. Ea should be lowered, however, since the catalyst provides a new, faster pathway between A and B. First rank situation! (606) 559-8612 Every degree matters. which is the least stable isomer of C4H8: methyl cyclopropane or cyclobutane and why? asked by Mischa on October 24, 2008; chemistry. But they differ by the position of double bond. Least stable chair Most stable chair 1 1 1 CH3!G = kcal/mol (e) For the isomer of 1-chloro-3,5-dimethylcyclohexane shown below, draw in bonds to CH3 and Cl groups as appropriate, to indicate the least and most stable chair conformers. [4 pts] Draw the most stable radical that could form upon hydrogen atom abstraction from the following molecule. There are three possible isomers of XeF2. Like all cyclopropanes, the last three isomers are unstable, since they have three carbon-to-carbon bonds at a 60-degree angle. This hydrocarbon has two hydrogens less, so it must contain either a double bond or a ring. The six possibilities are: But-1-ene. 00 PM (GMT). Draw the most stable chair form for the molecule (cis or trans, whichever is more stable) (groups in equatorial positions) and 2. Draw two constitutional (structural) isomers with the molecular formula C 4 H 10. Single-point energies were evaluated at the MP4, CCSD(T), MCSCF(11. 057 Hybrid-GGA B3PB6 II -0. Butene is an alkene with a rigid double bond in it. Highly flammable - readily forms an explosivemixture with air. In most cases, bromine will be added to the carbon with the fewest hydrogens attached to it C C H H H C H H H H + This carbocation intermediate is more stable because the methyl groups on either side of the positive carbon are electron releasing and reduce the charge on the ion which stabilises it. Two other isomers are known. For each of the four alcohols, predict the alkene product(s), including the expected major product, from an acid-catalyzed dehydration (E1) reaction. Draw the most stable chair conformer of the most stable isomer of 1,3,5-trimethylcyclohexane. A photoisomerization is the conversion of one isomer into another isomer by light. Write the expression to demo the possible geometric isomers of dibenzalacetone. For example, in the case of the C. Addition reactions are typically exothermic. Conformations of propane. For example, there are two isomers of butane. Geometric Isomerism - The existence of cis and trans isomers in compounds with the general formula [MX 2 Y 4]. Chain isomerism. Isomers are different compounds with the same molecular formula. The main difference between alpha and beta glucose is the position of the -OH group attached to their first carbon atom. Last Post; May 31, 2014; Replies 4 Views 5K. The six possibilities are: But-1-ene. Cyclohexane. Cyclopropane, C3H6, is converted to its isomer propylene, CH2=CHCH3, when heated. But these structures are not energy minima, and so they do not. equal to one. 4 °C, the trans isomer melts at 43 °C. Additional [1,2] H. These isomers are usually coproduced as a mixture and are commonly referred to as the C4 fraction. A saturated alkane would have a CnH2n+2 formula, or C4H10. 1 differ by one methylene group. The isomer with the methyl groups on the same side is called the cis isomer, while the isomer with the groups located on opposite sides is called the trans isomer. Of these ONLY ONE exhibits geometrical isomerism. Optical isomers are yet a third kind of isomer. For example, there are five C 6 H 14 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. Functional groups. H2C=CH-CH2-CH3 {or H3C-CH2-CH=CH2} its but-1-ene or 1-butene. 17b is more stable than the other. Best Answer: Cyclohexane is the most stable ring having this formula. 1-tert-butyl-3-methylcyclohexane c. Isomers Pentane is one of three structural isomers with the molecular formula C 5 H 12 , the others being isopentane and neopentane. Isobutylene is a colorless gas with a faint petroleum-like odor. Photoion mass spectrometry (PIMS) over the spectral range 7-22 eV was used to measure the appearance energies of the parent and fragment ions of six C 7 H 8 isomers, toluene, cycloheptatriene, norbornadiene, quadricyclane, spiro, hepta-4,6-diene and 1,6-heptadiyne (). Now make models of cis and trans 1,4-dimethylcyclohexane. The main difference between alpha and beta glucose is the position of the -OH group attached to their first carbon atom. When you draw them it is a good idea to have a system whereby you start with the longest chain, then move to shorter chains with an increasing number of. conformation? A. Ethane is a saturated molecule. What is the F-Xe-F bond angle in the more stable isomer? E. CONCEPT: THE OCTET RULE Atoms are most stable when they achieve the number of electrons necessary to reach a Noble Gas Configuration. Generally, 1º C-H bonds are stronger than 2º or 3º C-H bonds, so maximizing the number of methyl groups (and minimizing the number of 3º C-H bonds) leads to more stable isomers. Cis vs Trans Isomers and E vs Z Isomers. 2) • When 2 isomers can be converted to a common product, the relative magnitude of ΔH tells which isomer is more stable • The more heat released, the less stable the isomer. those with alternating double and single bonds). txt) or view presentation slides online. Consider the structure of the following solvents when answering the questions. Problem: Identify the more stable stereoisomer in each of the following pairs, and give the reason for your choice: (a) cis- or trans-1-Isopropyl-2-methylcyclohexane 🤓 Based on our data, we think this question is relevant for Professor Switzer's class at UCR. 1 Both of these stretches can be seen on the infrared spectra of the product. Why should the trans, trans isomer be the thermodynamically most stable one? Your Ad Here The trans configuration generally creates more separation between the substituents on adjacent atoms compared to the cis configuration. The other staggered conformation has a Me-Me dihedral angle of 60 degrees and is called gauche. On the templates below, draw the most stable conformer and calculate the total interaction energy. Remove sources ofigntion from the working area. Molecular Weight: 2-methylprop-1-ene is an alkene that is prop-1-ene substituted by a methyl group at position 2. First, most of the elements in the periodic table are metals, and almost all metals form complexes, so metal complexes are a feature of the chemistry of more than half the elements. The cis isomer in this case has a boiling point of 60. Trans isomers have higher melting point because they are more stable than cis isomers. The mass spectrum of an element reveals the abundances of these isotopes, which can be used to calculate the relative atomic mass of the element. See the following isomers of butene: Figure 7. For example, there are two isomers of butane. pptx), PDF File (. Because the isomers are so similar, their physical properties, such as boiling point, commercially available or easily made, and highly stable compared to most porous materials. (b) geometric isomers (c) conformational structures (d) identical structures (e) optical isomers 13. txt) or view presentation slides online. 2 methyl groups are more stable than 1 ethyl group so these two substituents have to be as far away from each other as possible to be the most stable and both must be in the equatorial position. 2-Methylpropene. Isomer counting. There is no "number of chain isomers formula" for alkanes, and the number quickly grows cumbersome (for example, decane, or C 10 H 22, has a whopping 75 isomers). The most stable isomer of C8H16 has to have a cyclohexane structure since it has the least amount of strain. The most stable (low energy) conformation is the one in which all of the bonds as far away from each other as possible (staggered when viewed end-on in a Newman projection). Hence these are called as positional isomers. cis-But-2-ene. In the second isomer, however, the styrene phenyl group is oriented towards the phenylimido ligand. Write an isomer of structure for a), b) and c) and name them. Coordination compounds are important for at least three reasons. The chair conformations with 2 equatorial methyls ad 1 axial methyls C. Show the reagents used to convert the starting material to the product. A saturated alkane would have a CnH2n+2 formula, or C4H10. relative cost of the two isomers. Geometric Isomerism - The existence of cis and trans isomers in compounds with the general formula [MX 2 Y 4]. The cis isomer's melting point is 13. Federal Government. 2-tert-Butylcyclohexanol, mixture of isomers 99% CAS Number 13491-79-7. (800) 955-7641 Title suggestion for beginners. ethane: C2H6 Once the two carbons are connected, there are only six additional bonding sites and these are filled by the six hydrogen atoms. Both 1-butene and 2-butene contain linear arrangement of carbons. (b) geometric isomers (c) conformational structures (d) identical structures (e) optical isomers 13. two linkage isomers. The trans, trans isomer is the most stable. In one of the isomers, the bond between the substituted carbon atoms is single bond while in the other it is a double bond. (c) the bromine atom in an axial position and the chlorine atom in an equatorial position. 1021/ja00705a004. what time does the sun go down. Not all coordination compounds have geometric isomers. Rank the following isomers by stability. There are three possible isomers of XeF2. Chain isomerism. Gilbert, John and Martin, Stephen, Experimental Organic Chemistry, Philadelphia: Saunders College Publishing, 1998. Note: Three possible suggestions for remembering this: E is for "Enemies", which are on opposite sides. stable Isomer is in large amount as compared to vinvl alcohol Since one of the i. Only by heating to 200 °C is the endo isomer transformed into the more stable exo isomer. tHere are 3 structural isomers possible for C4H8. In this geometry, the four carbons are in the same plane. Constitutional isomers. It is possible that lycopene exists in both human and animal tissues as ∼50% cis-lycopene because this mixture is the most stable and represents an equilibrium between trans-lycopene and its isomers. molecule from the central carbons? A. It is an alkene and a gas molecular entity. 1,4-diethylcyclohexane III. The chair conformations with 1 equatorial methyls ad 2 axial methyls D. of Chemical Sciences Bridgewater State College Bridgewater, MA 02325: Please read!Important notes about this presentation. MDL number MFCD00001472. 3: Trans-2-butene is the most stable because it has the lowest heat. (10 pts) Consider 2-bromobutane (shown). Transition Metals and Complex Ion Chemistry Definitions Complex ion - a metal ion with Lewis bases attached to it through coordinate covalent bonds. ((CH3)3C)4C ) or ring strain. Which isomerisms are shown by following. – example: C4H10 CH3CH2CH2CH3 Butane (bp -0. They are both excited – the last reported discovery of […]. 2-tert-Butylcyclohexanol, mixture of isomers 99% CAS Number 13491-79-7. (5) 1,3-dibromocyclobutane is also positional isomer of C 4 H 6 Br 2 and can exhibit E/Z (geometric) isomerism. Improve concepts using videos, connect with students and teachers globally. The experimental rotational parameters are in very good agreement with those computed using double hybrid functionals. 3: Trans-2-butene is the most stable because it has the lowest heat of hydrogenation. Notes The pi bond, in addition to the sigma bond, between the two alkene carbons cause the structure to be conformationally locked allowing for cis and trans geometric isomers. The IUPAC name for this compound is 1-tert-butyl-3-ethyl-5-methylbenzene. Both 1-butene and 2-butene contain linear arrangement of carbons. The most stable conformation (isomer) is the one that minimizes the mutual repulsion of bonded electron clouds on adjacent carbons. The reason for this is that the trans isomer is straighter, packs better, and hence – having a much higher melting point. 4 kcal/mol, and the smallest BDE in ClOOCl is the O-O bond with a. Therefore, each molecule will spend most of its time in its most stable conformation. The cis isomer in this case has a boiling point of 60. There are three possible isomers of BrF3. AU - Osborne, C. this stabality arises due to their shape, trans are strieght which allows H intermolecular forces to accure. e different structural formulae) normally the number of isomers increases as the number of carbon in a certain series increase!!!. The most stable alkene is 1, while the least stable alkene is 5. It is possible that lycopene exists in both human and animal tissues as ∼50% cis-lycopene because this mixture is the most stable and represents an equilibrium between trans-lycopene and its isomers. The most stable isomers release more energy when they are formed; the less stable isomers release less energy. We have seen examples on this type of isomers on page 21 in the hand out you have been given before. But, we can mainly divide the isomers into two groups as constitutional. Which of the following is the most stable isomer? Why is D the most stable isomer? Get more help from Chegg. Cyclobutane does not have as much strain as cyclopropane does and thus the answer must be. Despite the benign chemistry of cobalt(III) complexes, the Co(III) ion is not stable in water due to the hydrolysis reaction below. (Other types of reaction have been substitution and elimination). 4 kcal/mol) barrier to rotation in propane. We apologise for any inconvenience this might cause and thank you for your patience. Linear Formula (CH 3) 3 CC 6 H 10 OH. Draw both the eclipsed and staggered conformations of 2-chloropropane in the Newman projection looking down the C1-C2 bond. Throughout this contribution, for simplicity we will usually only quote energies from. Both halide atoms in axial positions. Draw the constitutional isomers for C4H8. 035a Hybrid-Meta-GGA TPSSh I 0. For transportation it may be stenched. Energies of minima and TS as well as characteristic NMR chemical shifts are reported for the parent unsaturated phospho-organic molecules with CP2 backbone. For nitrito isomer, these are the stretches of N=O bond which is observed at 1480-1380 cm-1, and the stretch of the N-O group that occurs at 1200-1050 cm-1. The less heat released, the more stable. Table A: Relative Energy Comparison of Most Stable Conformers. The key difference between cis and trans isomers is that the cis isomer has same atoms on the same side of the double bond whereas the trans isomer has two of the same atoms on the opposite sides of the double bond. Author information: (1)Hefei National Laboratory for Physical Sciences at Microscale, & Department of Materials Science and Engineering, University of Science and Technology of China (USTC. D on August 27, 2014; Chemistry- DrBob222. We'll do our best to fix them. C) tert-butyl is equatorial and the methyl is axial. 1,2-dibromocyclopentane can exist as two different stereoisomers: cis -1,2-dibromocyclopentane and trans -1,2-dibromocyclopentane. Sodium is present in fair abundance in the sun and stars. Both halide atoms in equatorial positions. Enols can be forms by acid or base catalysis from the ketone and are extensively used in making C-C single bonds in organic synthesis. In disubstituted alkenes, trans isomers are more stable than cis isomers due to steric hindrance. 5°C) CH3 CH3CHCH3 2-Methylpropane (bp -11. C 5 H 10, on the other hand, has three isomers, while C 6 H 14 has nine. ethane: C2H6 Once the two carbons are connected, there are only six additional bonding sites and these are filled by the six hydrogen atoms. OU Chemical Safety Data (No longer updated) More details. Geometric isomers are two or more coordination compounds which contain the same number and types of atoms, and bonds (i. Draw a functional group isomer of C4H8 that does not belong to this homologous series. Instead, you should be able to construct a few of them given a particular alkane formula. Draw figure to show splitting of d- orbitals in an octahedral crystal field. 7 61) Circle the alkene below which has the smallest heat of hydrogenation. Which of the following cyclohexane conformation is(are) consider to be cis. ASAP Flexible Luminescent MOF: Trapping of Less Stable Conformation of Rotational Isomers, In Situ Guest-Responsive Turn-Off and Turn-On Luminescence and Mechanistic Study ACS Applied Materials&InterfacesDOI: 10. It certainly has constitutional isomers: For example, the sum formula $\ce{C6H6}$ does describe benzene as well as hex-1,5-en-3-in $\ce{H2C=CH-C#C-CH=CH2}$. What is the F-Xe-F bond angle in the more stable isomer? E. – example: C4H10 CH3CH2CH2CH3 Butane (bp -0. So next would be the di-substituted alkene. There are different types of isomers: constitutional isomers, positional isomers, conformational isomers, configurational isomers (geometric and optical) and functional group isomers. In general the Keto form is more stable. Consequently, the boiling points of the branched chain alkanes are less than the straight chain isomers. This presentation is designed to be used as an adjunct to traditional lectures not as a replacement. The average rate constant determined was 6. The chain isomers have same molecular formula but different types of chains i. There are four isomeric alkenes of formula C4H8. Well, it depends on what kinds of isomers you have in mind. 1 triple bond. But, we can mainly divide the isomers into two groups as constitutional. We'll consider the intriguing problem of why 2-butene prefers the E isomer, while the. The most stable isomer of C8H16 has to have a cyclohexane structure since it has the least amount of strain. (MCP), the most stable C4H4•+ isomer. Rank by water solubility. That means that there are actually four isomers, not three if you go by merely the position of the double bond. Two distinct temperature regimes are clearly visible. Also, internal alkenes are more stable than terminal ones. but-1-ene cis but-2-ene (Z) but-2-ene trans but-2-ene (E) but-2-ene 2-methylpropene * YOU CAN GET ALKANES WITH FORMULA C4H8 IF THE CARBON ATOMS ARE IN A RING. An alkene that is prop-1-ene substituted. C 5 H 10, on the other hand, has three isomers, while C 6 H 14 has nine. Google Classroom Facebook Twitter. I suspect that it will be most useful as a. Choose the thermodynamically most stable isomer. 0 kJ/mol, a hydrogen-methyl eclipsing interaction costs 6. It is proposed that if each isomeric carbon cage for a given fullerene C is constructed such that no five-membered ring contains a double bond, then the most stable isomer is that containing the highest number of benzenoid rings ( those with alternating double and single bonds). The energy of the most stable isomer was considered as a reference to calculate the relative energy for other relevant isomers. The substance is toxic to lungs, the nervous system, mucous membranes. Remove sources ofigntion from the working area. This presentation is designed to be used as an adjunct to traditional lectures not as a replacement. The bromine atom in the equatorial position and the chlorine atom in the axial position. 8 kcal/mol, and neopentane by 5 kcal/mol. Last Post; Mar 17, 2017; Replies 2 Views 2K. This presentation is designed to be used as an adjunct to traditional lectures not as a replacement. A pyrethroid compound, therefore, consists of two to eight isomers. 1-tert-butyl-3-methylcyclohexane c. Both the MM Energy and the heat of formation from a semi-empirical calculation can be used to determine relative stabilities of isomers. Draw the most stable. Nuclear Isomer Definition Nuclear isomers are atoms with the same mass number and atomic number , but with different states of excitation in the atomic nucleus. Step 1: Decide if it is acylic or if it is cyclic. The most important isomer of this group is the 2. However, the cis isomer is. Isomerism and Stereochemistry. There are five constitutional isomers of formula C4H8:. Must explain your answer for each question. When the group of atoms that make up the molecules of different isomers are bonded together in fundamentally different ways, we refer to such compounds as constitutional isomers. The isomer with the methyl groups on the same side is called the cis isomer, while the isomer with the groups located on opposite sides is called the trans isomer. Most stable cis is one axial and one equatorial (i. Theoretical calculations performed to find stationary points on the potential energy surface confirm that the observed structure is the most stable form. Identify whether the more stable stereoisomer is cis (both up or both down) or trans (one up, one down) a. Geometry optimizations were carried out on stationary point conformations of seven configurational isomers at UHF, B3LYP, MP2, CISD, QCISD, MCSCF(7,7), and MCSCF(9,9) levels of theory. Which of the following statements concerning conformations is (are) TRUE? (1) Ethane has an infinite number of conformations. PUSAT ASASI SAINS. • Two types of stereoisomers are geometric isomers and optical isomers. Our new CrystalGraphics Chart and Diagram Slides for PowerPoint is a collection of over 1000 impressively designed data-driven chart and editable diagram s guaranteed to impress any audience. Step 1: Decide if it is acylic or if it is cyclic. Clearly label each structure. There are probably >30! What Rex has given is for the fully saturated C6H14 (e. Ab initio calculations have been carried out on the lowest energy isomers of C4H5 to predict spectroscopic properties and relative stabilities. Chain isomerism. 4-trimethylpentane (known as isooctane) because it is used as a reference value in the octane rating scale. 057 Hybrid-GGA B3PB6 II -0. Ans 1 : The molecular formula of C 6 H 14 contains the maximum number of H atoms for 6C (C n H 2n+2) so it can cannot contain double bonds or rings. Tracked the problem child has double doors?. 1-tert-butyl-3-methylcyclohexane c. What are they, what's the difference and when to use each case. Choose from 191 different sets of stereoisomers flashcards on Quizlet. For C4H8, the least stable isomer would have a cyclopropane structure with one methyl group. Examples include alkenes such as butene and alkanes such as cyclobutane and methylcyclopropane. To convert CBD (open form, Left) to THC (closed form) the hydroxyl group (blue arrow) needs to form a bond to carbon #5. WHY? The order of stability for carbocations is. Types of structural isomerism. Q: Sight down the C-2─C-3 bond, and draw Newman projection formulas for the (a) Most stable conformation of 2, 2-dimethylbutane (b) Two most Q: One of the staggered conformations of 2-methylbutane in Problem 3. The chain isomers have almost similar chemical properties but different physical properties. Generally, 1º C-H bonds are stronger than 2º or 3º C-H bonds, so maximizing the number of methyl groups (and minimizing the number of 3º C-H bonds) leads to more stable isomers. Two are cis-2-tert-butylcyclohexanol and two are cis-3-tert-butylcyclohexanol. The robust formulation provides stable catalyst operation and performance even with non-hydrotreated feeds containing higher quantities of sulfur. Arrange the four compounds in order of stability. So this one would be the least stable, and the tri-substituted would be the most stable. Functional groups. Reoptimize the geometry and save the structure of the most stable conformer of each isomer. Molekül-Mechanik-Rechnungen in der Organischen Chemie: Beispiele für die Nützlichkeit eines einfachen nicht-quantenmechanischen Modells. Which of the following conformation is the most stable conformation of butane, view the. There is no "number of chain isomers formula" for alkanes, and the number quickly grows cumbersome (for example, decane, or C 10 H 22, has a whopping 75 isomers). The most stable conformational isomer of cis - 1 - bromo - 2 - chlorocyclohexane will have bromine atom in an equatorial position and chlorine atom in axial position, so Br atom is larger in size so it will occupy equatorial position and cis geometry made chlorine atom to occupy axial position. (10 pts) Consider 2-bromobutane (shown). D) cis-1,4-diethylcyclohexane. A is a constitutional isomer of X and stereoisomer of Y. In the field of organic chemistry, cis isomers contain functional groups on the same side of the carbon chain whereas the functional groups are on opposite sides in trans isomers. (10 pts) Draw both the cis and trans isomer of 1-chloro-3-ethylcyclohexane (pictured), each as a pair of chair conformers. Which isomerisms are shown by following. In disubstituted alkenes, trans isomers are more stable than cis isomers due to steric hindrance. Can you please write the isomer name though? I will draw it from that. There are various types of isomers. There are also a lot ring structures that are isomers of benzene:. Which of the following cyclohexane conformation is(are) consider to be cis. Derivatives of cyclobutane are called cyclobutanes. Circle the most stable of the two. The chair conformations with 1 equatorial methyls ad 2 axial methyls D. Single-point energies were evaluated at the MP4, CCSD(T), MCSCF(11. Remember isomerism is a property between a pair (or more) of molecules, i. 2-tert-Butylcyclohexanol, mixture of isomers 99% CAS Number 13491-79-7. Google Classroom Facebook Twitter. Draw figure to show splitting of d- orbitals in an octahedral crystal field. Remove sources ofigntion from the working area. It certainly has constitutional isomers: For example, the sum formula $\ce{C6H6}$ does describe benzene as well as hex-1,5-en-3-in $\ce{H2C=CH-C#C-CH=CH2}$. It can have three structures of 1 double bond: It can have two structures of 1 ring: Now for D. 60 per gram for the cis isomer but only $0. Basic aspects of Stereochemistry 1. cis-1-bromo-2-chlorocyclohexane Isomer. VitaMK7® is the most stable form of Menaquinone-7: Stable both as stand-alone and in formulations Stable for 36 months at room temperature protected from light Stable in liquid (water, yogurt, oil) and milk powder formulations. 4 Heats of combustion of C4H8 isomers. In the context of chemistry, cis indicates that the functional groups are on the same side of the carbon chain while trans conveys that functional groups are on opposing. The chair conformations with 1 equatorial methyls ad 2 axial methyls D. The prefixes "cis" and "trans" are from Latin: "this side of" and "the other side of", respectively. Unlike its electronic energy, isotropic magnetizability of benzene is slightly lower than the average magnetizability of its isomers. I count six isomers of "C"_4"H"_8. Ch08 Reacns of Alkenes (landscape) Page 1 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. Which of the following is the most stable isomer? Why is D the most stable isomer? Get more help from Chegg. 5, and transition states are illustrated in association with following individual discussions of each reaction. All undergo combustion according to the equation When the heats of combustion of the isomers are plotted on a common scale as in the figure, we see that the isomer of highest energy (the least stable one) is 1-butene, CH2=CHCH2CH3. (E,E) This is due to sterics. In the options given below the isomer given in the option A of 1-tert-butyl-5-methylcyclohexane is the most stable of all. The best agreement with the experiment is found for the most unstable isomer, labelled as T. You don't, of course, need a way of remembering the Z as well - it's just the other way around from E. The recent suggestion, based on gas-phase experimental data, that the most stable isomer of protonated benzene has a face-protonated π-complex structure is not supported by our detailed computations which indicate that the π-complex is a second-order saddle point on the potential energy surface, lying 199 kJ mo -1 higher in energy than the well-established C 2v σ-protonated structure. We propose that the second isomer of 19 (isomer B) has a very similar structure to the isomer A, shown in Figure 3. May 2002; Journal of the American Chemical Society 92(2) DOI: 10. The most stable (low energy) conformation is the one in which all of the bonds as far away from each other as possible (staggered when viewed end-on in a Newman projection). Cyclobutane does not have as much strain as cyclopropane does and thus the answer must be. 039 GGA PBE II -0. The trans isomers have lower densities than their cis counterparts. Q: Sight down the C-2─C-3 bond, and draw Newman projection formulas for the (a) Most stable conformation of 2, 2-dimethylbutane (b) Two most Q: One of the staggered conformations of 2-methylbutane in Problem 3. 2007,,, 63-117. in terms of cyclic alkanes. Stability of Dibenzalacetone Isomers: In the synthesis of dibenzalacetone by aldol condensation of acetone with benzaldehyde 1 the primary product melts at 110-112° C and has a intense uv absorption at 330 nm. Information about two of these isotopes is given. 4 kcal/mol) barrier to rotation in propane. 2-methylprop-1-ene. It is shipped as a. The isomers of a chiral compound often differ from each other in their biological properties. PUSAT ASASI SAINS. 015 Meta-GGA TPSS II -0. Cyclobutane itself is of no commercial or biological significance, but more complex derivatives are important in biology and biotechnology. (b) Most elements exist naturally as a mixture of isotopes, each with their own relative isotopic mass. 1 lists the heat of combustion data for some simple cycloalkanes. It is shipped as a. Well, it depends on what kinds of isomers you have in mind. Draw the most stable conformer and calculate the total interaction. Step 1: Decide if it is acylic or if it is cyclic. Both the MM Energy and the heat of formation from a semi-empirical calculation can be used to determine relative stabilities of isomers. 2) • When 2 isomers can be converted to a common product, the relative magnitude of ΔH tells which isomer is more stable • The more heat released, the less stable the isomer. Most C4H8[radical sign]+ isomers are demonstrated to be mutually accessible below the threshold for the lowest energy dissociation, consistent with inferences from earlier experimental data. Butane (/ ˈ b juː t eɪ n /) is an organic compound with the formula C 4 H 10 that is an alkane with four carbon atoms. See the following isomers of butene: Figure 7. C5H12 C3H6(propene) KBrO3 C3H8 AgNO3 C4H8(cyclobutane) None. The trans, trans isomer is the most stable. Federal Government. Explains the E-Z notation for naming geometric isomers. For example, in the case of the C. The most basic five carbon chain will have a chemical formula of: C 5 H 12, but as pentene has a double bond, it has two less hydrogen atoms. Related Threads on Most stable isomer Most stable Lewis structure. A) tert-butyl is axial and the methyl is equatorial. (10 pts) Consider the general reaction of A to B. This tells me that it is the most stable and less volatile than the other isomers which have a lower thaw point. Indicate which is the more stable conformation for each pair, and indicate which of all four conformations is the most stable. Butanol isomers A detailed chemical kinetic mechanism has been developed and validated using experimental data from shock tubes, a rapid compression machine (RCM) and a jet stirred reactor (JSR). The food matrix that surrounds lycopene when it is present within the tomato seems to prevent this isomeric equilibrium from occurring. The examples we will look at involve exclusively the conversion between two geometric isomers. In order to establish a baseline of behavior against which these reactions may be ranked, we need to investigate the reactivity of compounds lacking any functional groups. This hydrocarbon has two hydrogens less, so it must contain either a double bond or a ring. Conformations of ethane. Beginning with butane (C 4 H 10 ), and becoming more numerous with larger alkanes, we note the existence of alkane isomers. λ Example: H H light of H Cl C == C → C == C Cl Cl appropriate Cl H energy (The Greek letter λ signifies light. Australians hope to open another dimension in chemistry. Author information: (1)Hefei National Laboratory for Physical Sciences at Microscale, & Department of Materials Science and Engineering, University of Science and Technology of China (USTC. 7 62) Which has the smaller heat of hydrogenation, (E)-2-pentene or (Z)-2-pentene? What is the structural origin of this difference? Answer: (E)-2-pentene has the smaller heat of hydrogenation. Now make models of cis and trans 1,4-dimethylcyclohexane. In the Conformational isomers we can convert from one isomer to other isomers by just rotation about C-C bonds. Chemical and Physical Properties of Gold There is only one stable isotope of gold: Au-197. EC Number 236-806-6. A Complex (or Coordination compound) is a compound consisting either of complex ions with other ions of opposite charge or a neutral complex species. 3 Isomers • Structural isomers differ in physical proper-ties and have different chemical reactivites. The chair conformations with 1 equatorial methyls ad 2 axial methyls D. It certainly has constitutional isomers: For example, the sum formula $\ce{C6H6}$ does describe benzene as well as hex-1,5-en-3-in $\ce{H2C=CH-C#C-CH=CH2}$. All smaller rings, cyclopropane, cyclobutane and cyclopentane are less stable. Chemical and Physical Properties of Gold There is only one stable isotope of gold: Au-197. Chart and Diagram Slides for PowerPoint - Beautifully designed chart and diagram s for PowerPoint with visually stunning graphics and animation effects. Most C4H8+ isomers are demonstrated to be mutually accessible below the threshold for the lowest energy dissociation, consistent with inferences from earlier experimental data. If gold chloride is heated gently, it will decompose to release the pure elements again. all of these ____ 8. 1 Both of these stretches can be seen on the infrared spectra of the product. When the group of atoms that make up the molecules of different isomers are bonded together in fundamentally different ways, we refer to such compounds as constitutional isomers. 1 kcal/mol at 298 K. (5) 1,3-dibromocyclobutane is also positional isomer of C 4 H 6 Br 2 and can exhibit E/Z (geometric) isomerism. AU - Ciocca, Daniel R. Only difference in these compounds is 2-methyl propane has 3 carbon atoms in main carbon chain and there is CH3- group in 2nd C atom while butane has 4 carbon atoms in. , acctatdchydc contains a keto group and the other, i. Derivatives of cyclobutane are called cyclobutanes. Eventually, trans isomers become more stable than cis isomers once the ring contains more than eleven carbons,. [4 pts] Draw the most stable radical that could form upon hydrogen atom abstraction from the following molecule. Criteria to predict experimentally stable allotropes of a "funnel" in an energy landscape of isomers, penta-graphene is part of the "funnel" that leads to graphene as the most stable structure. Theoretical studies revealed that the pyrogenic synthetic method used enables reactants to overcome the. AU - Degregorio, Michael W. The ClOClO isomer is less stable than ClOOCl by 8. 4 °C, the trans isomer melts at 43 °C. Enterotoxigenic Escherichia coli (ETEC) is responsible for 280 million to 400 million episodes of diarrhea and about 380,000 deaths annually. TITLE OF WORK The synthesis and characterisation of functionalized porous organics AbstractLophine based radicals have been studied for many years due to their photochromic nature, recent literature has seen attempts to connect two radicals to carbon based backbones. Sighting along the C2-C3 bond and using Newman projections: a. A fifth and sixth hydrocarbon of the same composition exists, but they’re not alken. All undergo combustion according to the equation When the heats of combustion of the isomers are plotted on a common scale as in the figure, we see that the isomer of highest energy (the least stable one) is 1-butene, CH2=CHCH2CH3. Isomer A: Isomer B: Isomer C: c. See the following isomers of butene: Figure 7. There is no "number of chain isomers formula" for alkanes, and the number quickly grows cumbersome (for example, decane, or C 10 H 22, has a whopping 75 isomers). 2-tert-Butylcyclohexanol, mixture of isomers 99% CAS Number 13491-79-7. In this second example, two structural chain or skeletal isomers are observed; both have the same formula (C 4 H 10 O) and the same substituent (OH), but the isomer on the left is straight chain (1-butanol), while the one on the right has a branched structure (2-methyl-2-propanol). (b) both halide atoms in equatorial positions. The thermodynamic product has a higher activation energy, which was expected to affect the yield of each isomer. 1,2-Dimethylcyclopropane There are two stereoisomers of 1,2-dimethylcyclopropane. It is shipped as a. Given cyclohexane in a chair conformation, substitute two of the H labels with Br to construct the most stable isomer and conformation of 1,3-dibromocyclohexane. They took samples from more than 1000 women, but analyzed them for only a few pesticides. Carbohydrates are the most abundant biomolecules on earth. Your possible cycloalkanes are: (A) 1,2-dimethylcyclopropane (B) 1,1-dimethylcyclopropane. , the connectivity between atoms is the same), but which have different spatial arrangements of the atoms. The most stable isomer of C8H16 has to have a cyclohexane structure since it has the least amount of strain. The most water soluble compound is 1, while the least water soluble compound is 5. The food matrix that surrounds lycopene when it is present within the tomato seems to prevent this isomeric equilibrium from occurring. Isomers of Organic Compounds, An Introduction: By: Frank R. 2 posts • Page 1 of 1. Step 1: Decide if it is acylic or if it is cyclic. 2007,,, 63-117. There are. Malleable means capable of being hammered into thin sheets. Indicate which is the more stable conformation for each pair, and indicate which of all four conformations is the most stable. Ethene can be converted into a variety of useful products as illustrated. The branched isomers are more stable than pentane, which means that they have lower heat of formation and heat of combustion. Check Answer and Solution for above Chemistry question - Tardigrade. Australians hope to open another dimension in chemistry. HUMAN STUDIES: 1-Butene is a simple asphyxiant and may be a CNS depressant in high concentrations. 1021/acsami. Table of Content. (same for determining stabilities of any other compounds: lowest = most stable) Top. Benzene is the global minimum on the potential energy surface of C 6 H 6, 35 kcal mol −1 lower in energy than the second most stable isomer, fulvene. General formula for alkanes is C n H 2n+2. It is proposed that if each isomeric carbon cage for a given fullerene C n is constructed such that no five-membered ring contains a double bond, then the most stable isomer is that containing the highest number of benzenoid rings (i. 3 Isomers • Structural isomers differ in physical proper-ties and have different chemical reactivites. Heats of combustion. Hydrocarbon structures and types of isomerism (structural isomers, cis/trans isomers, and enantiomers). The names of the various forms of structural isomerism probably don't matter all that much, but you must be aware of the different possibilities when you come to draw isomers. Ring Strain. E) All are equally stable. Cyclohexane. By Arthur Winter. , the connectivity between atoms is the same), but which have different spatial arrangements of the atoms. AU - Degregorio, Michael W. Step 2: Draw different. 2-methylprop-1-ene. Reoptimize the geometry and save the structure of the most stable conformer of each isomer. The keto tautomer is typically much more stable than the enol form, with K's of about 10 to the -5th power. It is possible that lycopene exists in both human and animal tissues as ∼50% cis-lycopene because this mixture is the most stable and represents an equilibrium between trans-lycopene and its isomers. Both halide atoms in equatorial positions. Clearly label each structure.
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