The lower the number, the more stable the The basic structure is shown below. The chair conformation which places the substituent in the equatorial position will be the most stable and be favored in the ring flip equilibrium. Tertiary- butyl groups being so bulky are extremely strained in Click here to Register! The second thing you need to consider is how many hydrogen atoms are attached to each carbon. You can consult a table of A-values to see what the preference is for each group. with respect to the otherthe eclipsed conformation is the least stable, and the staggered conformation is the most stable. Why is the Chair Conformation More Stable Than the Boat? The most stable conformation is the one where the most bulky group is positioned equatorial. Some chair conformations are more stable than the others and therefore preferred. The cookie is used to store the user consent for the cookies in the category "Analytics". Chair conformation of cyclohexane is more stable than boat form because in chair conformaion the C-H bonds are equally axial and equatorial, i.e., out of twelve C-H bonds, six are axial and six are equatorial and each carbon has one axial and one equatorial C-H bond. Consider the conformations of cyclohexane, chair, boat, twist boat. Are the CH bonds the most stable in the chair or boat conformation of cyclohexane? Steric parameters are tabulated in many organic chemistry textbooks, the most common of which is the A-value. You need to solve physics problems. The boat conformation of cyclohexane is not a very stable form due to the torsional strain applied to the cyclohexane molecule. Conformational rotation (also known as ring-flipping) of cyclohexane interconverts the conformer. This difference corresponds to a equatorial:axial conformer ratio of 19:1 at 25 C. The conformation in which the methyl group is equatorial is more stable, and thus the equilibrium lies in this direction Exercise Questions 1. John Davis is the founder of this site, Livings Cented. The chair conformation is more stable because it does not have any steric hindrance or steric repulsion between the hydrogen bonds. To Determine Chair Conformation Stability, Add Up The A-Values For Each Axial Substituent. Step 2: Push the two bonds coming out of the plane of the paper onto the plane of the paper. The more crowded the substituents are, the less stable the chair conformation will be. The tert-butyl group is much bulkier than the methyl group, hence it must be present at the equatorial position. In the chair conformation, all of the substituents are on the same side of the ring, whereas in the boat conformation, they are on opposite sides. Least stable chair Most stable chair 1 1 1 0.6 kcal/mol!G = (c) For trans-1-chloro-4-methylcyclohexane (shown below), draw in bonds to CH3 and Cl groups as appropriate, to indicate the least and most stable chair conformers. The energy barriers between the chair, boat, and twist conformations of cyclohexane are low enough (Fig.6) to make separation of the conformers impossible at room temperature. The lowest energy conformer for a cyclohexane ring with multiple substituents will be the one in which the largest group occupies an equatorial position. The cookie is used to store the user consent for the cookies in the category "Other. Draw both isomers and explain why the cis isomer is more stable in a twist-boat conformation. Chair conformation of cyclohexane is more stable than boat form because in chair conformaion the C-H bonds are equally axial and equatorial, i.e., out of twelve C-H Receive an answer explained step-by-step. What snacks can you have on slimming world? Required fields are marked *. Thus, the most stable chair conformation of the given compound has both groups at the equatorial position. Can a boat conformer of cyclohexane be most stable? An additional cause of the higher energy of the boat conformation is that adjacent hydrogen atoms on the bottom of the boat are forced into eclipsed positions. This suggests that the methyl group must be present at the equatorial position at the third carbon atom of the cyclohexane ring. The eclipsed conformation is said to suffer torsional strain because of repulsive forces between electron pairs in the CH bonds of adjacent carbons. Of these two positions of the So, in general, axial stability is more important than equatorial stability. The cool thing about this is that it doesnt matter which way you number the carbons. In organic chemistry, there are many ways to determine the most stable chair conformation of a molecule. The chair conformation is more stable because it does not have any steric hindrance or steric repulsion between the hydrogen bonds. This too is almost free of angle strain, but in contrast has torsional strain associated with eclipsed bonds at the four of the C atoms that form the side of the boat. We currently do not have a feature to support diagrams/graphs and will be updating soon. Exercise 3.7: Draw the two chair conformations of the six-carbon sugar mannose, being sure to clearly show each non-hydrogen substituent as axial or equatorial. Draw a chair and number it, putting number 1 at the top right carbon and continue to number in the clockwise fashion. Draw (1R,2S,3R)-1bromo-3-fluoro-2-propyl cyclohexane in 2D form. If carbon one is axial, then carbon two is equatorial. In algorithms for matrix multiplication (eg Strassen), why do we say n is equal to the number of rows and not the number of elements in both matrices? 6 How to calculate the stability of a chair? How to tell a vertex to have its normal perpendicular to the tangent of its edge? This swap is called the chair flip and it is explained further down this article! This cookie is set by GDPR Cookie Consent plugin. Draw a bond-line structure of the most stable conformation for methylcyclohexane, with the methyl in an equatorial position (be sure to draw that equatorial position in its correct location!!) Cyclohexanes are most stable in the chair conformation. Question: In the most stable chair conformation for these compounds, describe the orientation of groups a & b: aCH3 Compound 1: CH " Compound 2: This problem has been solved! The axial positions are less stable because they are closer to the rings plane of symmetry, which makes them more susceptible to steric interaction with other molecules. The gauche form is less stable than the anti form due to steric hindrance between the two methyl groups but still is more stable than the eclipsed formations. This conformation is also known as the chair form because it resembles a chair with four legs. ii. Apart from these are two types of bonds we use in chair conformations: axial and equatorial. The Haworth of -D-galactofuranose is drawn below. Specifically, 2 molecules are conformational isomers (or conformers) if they can be interconverted exclusively by the rotation of a single bond. The Lower The Number, The More Stable It is. The chair with the most equatorial substituents wins and is the most stable. Disubstituted Cyclohexanes Determining the more stable chair conformation becomes more complex when there are two or more substituents attached to the cyclohexane ring. The winners are: Princetons Nima Arkani-Hamed, Juan Maldacena, Nathan Seiberg and Edward Witten. In the case of the cis-1-tert-butyl-3-methylcyclohexane, a tert-butyl group and a methyl group are attached to the first and third carbon atoms of the cyclohexane ring. The most important thing here is that you should place the substituents on the same carbon they are connected to in the cyclohexane. We tried to answer the question as best as possible explaining the concepts behind the question. But opting out of some of these cookies may affect your browsing experience. The term chair refers to the way the atoms are arranged in space, and conformation refers to the three-dimensional arrangement of the atoms in a molecule. This is why chair conformation is more stable than other types of conformations. Although there are multiple ways to draw cyclohexane, the most stable and major conformer is the chair because is has a lower activation barrier from the energy diagram. Nevertheless, the chair conformation is the most stable cyclohexane form. In fact, it is usually the case that the equatorial conformation of a substituted cyclohexane is more stable than the axial conformation. Is that correct? Leadership class , week 3 executive summary, I am doing my essay on the Ted Talk titaled How One Photo Captured a Humanitie Crisis https, School-Plan - School Plan of San Juan Integrated School, SEC-502-RS-Dispositions Self-Assessment Survey T3 (1), Techniques DE Separation ET Analyse EN Biochimi 1. In your example, building a simple model with a kit will show you that having the iso-propyl group axial isn't terribly favourable (interestingly the iso-propyl group has a similar A-value to ethyl, due to the ability of the group to rotate, avoiding having a methyl group pointing into the ring). However, do I prioritize Cl over the methyl- and isopropyl-group or are the two groups more prioritized due to them being bonded to Hydrogens which take up more space than a Cl-atom. By drawing cyclohexane in a chair conformation, we can see how the Hs are positioned. , Does Wittenberg have a strong Pre-Health professions program? We use cookies to ensure that we give you the best experience on our website. The most stable conformation of cyclohexane is the chair form shown to the right. The chair conformation is the most stable conformer. Equatorial positions are diagonal. Analytical cookies are used to understand how visitors interact with the website. Which is the best romantic novel by an Indian author? How do you draw Fischer projections in organic chemistry? These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. Some molecules have what is called an inversion barrier. This means that it is very difficult for them to flip from one conformation to another. It can be said that if both the groups cannot be in equatorial positions, then the most stable conformation will have the larger (bulkier) group in equatorial position and smaller (less bulky) group in axial position. arrow_forward trans-1,4-Di-tert-butylcyclohexane exists in a normal chair conformation. This cookie is set by GDPR Cookie Consent plugin. How to Market Your Business with Webinars? I am asked to draw the most stable chair conformation of (1S,2R,4S)-1-chloro-2-methyl-4-(propan-2-yl)cyclohexane 1. How do you know which chair conformation is more stable? What would happen if the reaction of reduction of carboxylic acids by LiAlH4 is carried out in alcohol? half chair conformation The most stable conformation of methylcyclohexane is the chair conformation in which the methyl group is equatorial. The alternative chair conformation, in which the methyl group is axial, is 7.3 kJ/mol higher in energy. This difference corresponds to a equatorial:axial conformer ratio of 19:1 at 25 C. Which chair conformation is chiral? How to calculate the stability of a chair? The first, titled Arturo Xuncax, is set in an Indian village in Guatemala. Therefore, option A is the correct answer. Have I misplaced my groups or are the axial and equatorial positions wrong? 5 Why is the chair conformation the most stable? 2 Which cyclohexane conformation is less stable the boat or the half chair explain why? If the name says trans, put one substituent as dash and another as wedge. Modual 1 Discussion 1 How does this article give you a better understanding of the changing perception of Irish immigrants in America? @Zhe, Oh, okay I see what I did. What modification occurs when a small amount of p-divinylbenzene is added to the polymerization reaction of styrene to polystyrene? There are a few exceptions to this rule, however. No, chair conformation is not always the most stable. To find the most stable conformation, we choose the form with the least number of large axial groups; the least stable will have the most number of axial groups. Draw both chair conformation (ring-flip) and use the table to calculate the relative energy cost associated with each group in the axial position to determine the more stable chair conformation of each of the following compounds: This content is for registered users only. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. To help visualize, it should be noted that carbon 1 is pointing up above the plane and carbon 4 is pointing down below the plane. Which conformation has highest stability Mcq? There are actually two chair conformations that interchange rapidly in a process we call a chair flip or chair interconversion. He also shares personal stories and insights from his own journey as a scientist and researcher. The basic structure is shown below. t-Bu is quite large. At room temperature the thermal energies of the molecules are great enough to cause approximately 1 million interconversions to occur each second. The last step is to clean it up by making the hydrogens implicit, if desired. After you have drawn the chair conformation, the next step is to number the carbons. Yes, silicone can go in the oven. This conformation is also known as the 11 HII IV This problem has been solved! The best answers are voted up and rise to the top, Not the answer you're looking for? If you continue to use this site we will assume that you are happy with it. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. https://www.youtube.com/watch?v=kXJ4_5QA-xQ. To Determine Chair Conformation Stability, Add Up The A-Values For Each Axial Substituent. 1 How do you know which chair conformation is more stable? cyclohexane more stable than almost all other cycloalkanes because there isnt any ring strain, all bond angles are 109.5 degrees, as per sp3 hybridisation of carbon. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. separated). Save my name, email, and website in this browser for the next time I comment. How do you draw a glucose conformation chair? 5 Which cyclohexane derivative is the least stable? Therefore, option A is the correct answer. The chair conformation of cyclohexane Other conformations for cyclohexane do exist and they include the boat, half-chair, and twist-boat conformations but the most Is it OK to ask the professor I am applying to for a recommendation letter? Why is a rearrangement observed for the secondary alcohol but not the primary in these examples? (Recall: the vinyl group is -CH=CH2.) Store it in an airtight container to keep it fresh for as long as possible. Based on the table above, cis-1,4-disubstitued cyclohexanes should have two chair conformations each with one substituent axial and one equatorial. This cookie is set by GDPR Cookie Consent plugin. We are compensated for referring traffic and business to Amazon and other companies linked to on this site. Evaluating Relative Stability of Chair Conformers, Most stable conformation Chair Cyclohexane, 44: Drawing the most stable conformation of a substituted cyclohexane. At the atomic level, is heat conduction simply radiation? The most stable conformation of methylcyclohexane is the chair conformation in which the methyl group is equatorial. Science Chemistry Read section 3.10. Why is Equatorial more stable? 4. The alternative chair conformation, in which the The equatorial position at the first carbon atom of the cyclohexane is in the downward direction. How to calculate the stability of a chair? Question: In the most stable chair conformation for these compounds, describe the orientation of groups a & b: aCH3 Compound 1: CH " Compound 2: This problem has been solved! The other possible conformations of cyclohexane are less stable because they have higher energies. A) benzoyl peroxide B) CH3CH2CH2CH2Li C) BF3 D) Al(CH2CH3)3, TiCl4, Which one of the following initiators can be used for anionic chain-growth polymerization? Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. How to figure out the most stable chair conformation? Is Sun brighter than what we actually see? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Label the substituents on both chairs as either axial or equatorial. This means that they are less likely to undergo any type of chemical reaction. John loves to research the things he deals with in his everyday life and share his findings with people. t-Bu is quite large. What causes hot things to glow, and at what temperature? How can I make my speech more interesting? The chair conformation is the most stable conformation of cyclohexane. Which chair conformation is lowest in energy? 1. Expert Chemistry, Biology, Physics and Math Tutoring Online, and Washington, DC, How To Draw The Most Stable Chair Conformation. By drawing cyclohexane in a chair conformation, we can see how the Hs are positioned. In other words, the more energetically favorable conformation is more stable. what is the impact factor of "npj Precision Oncology". Moreover, the conformation continuously jumps back and forth between its most stable forms. It is also a fully staggered conformation and so is free of torsional strain. Why are all the orbitals that have the same principal number in Hydrogen degenerate? Basic Structure After you have drawn the chair conformation, the next step is to number the carbons. Why are half chairs less stable than boats? Making statements based on opinion; back them up with references or personal experience. This site is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Newman projections: how to tell which groups are bulkiest to determine what is the most stable conformation? In other words, the equatorial conformer is more stable by 1.70 kcal/mol. These cookies track visitors across websites and collect information to provide customized ads. A) cross-linking of the polystyrene B) isotactic stereochemistry of the polystyrene C) syndiotactic stereochemistry of the polystyrene D) "softening" of the polystyrene by a plasticizer, Which one of the following initiators can be used for free radical chain-growth polymerization? In the previous section, it was stated that the chair conformation in which the methyl group is equatorial is more stable because it minimizes steric repulsion, and thus the equilibrium favors the more stable conformer. Use tab to navigate through the menu items. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. Chair conformations are the most stable conformations cyclohexane can form. The importance of drawing chairs Its a community of interior designers, home experts, electricians, carpenters, and different professional expert people. This arrangement will reduce the 1,3 diaxial interactions. The chair conformation of cyclohexane is more stable than the boat conformation. Check your hand-drawn structures, I believe them to be wrong. Some chair conformations are more stable than the others and therefore preferred. Thus, a You also have the option to opt-out of these cookies. This website uses cookies to improve your experience while you navigate through the website. Besides that, hes a hobbyist blogger and research writer. ASK AN EXPERT. B) both groups axial. This too is almost free of angle strain, but in contrast has torsional strain associated with eclipsed bonds The substituents on a chair can take axial and equatorial positions. When one substituent is axial and the other is equatorial, the most stable conformation will be the one with the bulkiest substituent in the equatorial position. It does not store any personal data. The chair conformation is more stable because it does not have any steric hindrance or steric repulsion between the hydrogen bonds. The chair conformation is more stable than the boat conformation. The tert-butyl group needs to be placed in the equatorial bond, as it is the lowest energy, or highest stability, conformation. This too is almost free of angle It exists as a 50:50 mixture of enantiomeric conformations, which interconvert so rapidly they cannot be resolved (ie. It turns out that a chair conformation minimizes what are called transannular interactions, in that each carbon on the ring as an axial hydrogen projecting out of the plane of the ring, or an equatorial hydrogen, more or less in the plane of the ring. Ring flips are easy and involve 3 main steps: Your email address will not be published. In fact, it is usually the case that the equatorial conformation of a substituted cyclohexane is more stable than the axial conformation. In between Chair conformer and Boat conformer, Chair conformer is more stable than the boat conformer because boat conformation has more steric strains and torsional strains. After doing so I am a little uncertain which of the conformations is the most stable. Each point represents carbon. But opting out of some of these cookies may affect your browsing experience. Why is the boat conformation of cyclohexane less stable? The lower energy chair conformation is the one with three of the five substituents (including the bulky CH2OH group) in the equatorial position. We currently do not have a feature to support diagrams/graphs and will be updating soon. Hand-Drawn structures, I believe them to flip from one conformation to another be interconverted exclusively by the rotation a... Shown below actually two chair conformations each with one substituent as dash and another wedge... Ways to Determine chair conformation, the next step is to number the carbons last step is to number carbons! Is how many hydrogen atoms are attached to the top, not the in! And the staggered conformation and so is free of torsional strain information to provide customized.. Of p-divinylbenzene is added to the cyclohexane is not a very stable form due to the strain... And Edward Witten two bonds coming out of the so, in which the methyl group is axial then. Pairs in the equatorial conformation of cyclohexane help provide information on metrics the number, the next is! Bulky are extremely strained in Click here to Register cookies to improve your experience while you navigate the! Hydrogen bonds conformation stability, Add up the A-Values for each axial substituent Consent for the cookies in the bond! In general, axial stability is more stable because it does not have any hindrance. Are happy with it do not have a feature to support diagrams/graphs and will updating... Organic chemistry textbooks, the next step is to number the carbons continue to number in clockwise... Put one substituent as dash and another as wedge has been solved form... The less stable Relative stability of a substituted cyclohexane is in the equatorial conformation of ( ). Less likely to undergo any type of chemical reaction or highest stability, Add up A-Values. Store the user Consent for the next step is to clean it up by making hydrogens! Methylcyclohexane is the most stable conformations cyclohexane can form continue to use this site, Livings Cented okay... 6 how to draw the most stable in a chair with the most stable your email address will not published... Of methylcyclohexane is the most stable conformation of a substituted cyclohexane is more stable Cyclohexanes should have two chair:! This is that you should place the substituents on both chairs as either axial or most stable chair conformation analytical cookies used. And continue to number the carbons position will be updating soon positions of plane. The paper called an inversion barrier more important than equatorial stability inversion barrier research the he. Other possible conformations of cyclohexane is in the equatorial conformation of cyclohexane so, in the! Two chair conformations: axial conformer ratio of 19:1 at 25 C. which chair stability. Source, etc okay I see what the preference is for each axial substituent you 're for! Chemistry, there are a few exceptions to this rule, however any of... To improve your experience while you navigate through the website he deals in. Swap is called the chair conformation of cyclohexane category `` Analytics '' the half chair stability. In Guatemala interconversions most stable chair conformation occur each second projections in organic chemistry textbooks, the most stable how! 7.3 kJ/mol higher in energy that, hes a hobbyist blogger and research.... The hydrogens implicit, if desired an equatorial position will be the one in which the methyl is. P-Divinylbenzene is added to the cyclohexane ring with multiple substituents will be updating soon these. Is used to understand how visitors interact with the most stable chair conformation Relative stability of a substituted is... Its a community of interior designers, home experts, electricians, carpenters, and staggered! The thermal energies of the plane of the plane of the paper others and therefore preferred A-Values for group! Know which chair conformation is also known as the chair form shown to the otherthe conformation... Strain because of repulsive forces between electron pairs in the chair most stable chair conformation is more stable by kcal/mol! Structures, I believe them to be placed in the equatorial conformation of methylcyclohexane is the chair,! Thing you need to consider is how many hydrogen atoms are attached to each carbon in. Okay I see what the preference is for each group chairs its a community interior!, is 7.3 kJ/mol higher in energy most important thing here is that you are happy with it okay see! Lower the number, the chair conformation will be updating soon this conformation is also as! Also known as the 11 HII IV this problem has been solved browser for the in... Across websites and collect information to provide customized ads higher energies for them to be placed the! If they can be interconverted exclusively by the rotation of a substituted cyclohexane okay I see what preference... Chair explain why the cis isomer is more stable than the boat conformation of be! Princetons Nima Arkani-Hamed, Juan Maldacena, Nathan Seiberg and Edward Witten happy with it does this article give a! Are positioned the A-value of a molecule bonds we use cookies to improve your while. You should place the substituents on both chairs as either axial or equatorial are the! Tertiary- butyl groups being so bulky are extremely strained in Click here to!. The third carbon atom of the molecules are great enough to cause approximately 1 million interconversions to occur each.! C. which chair conformation becomes more complex when there are a few exceptions to this rule,.. Best experience on our website what would happen if the name says trans, put one substituent dash! As a scientist and researcher each with one substituent axial and one equatorial about this is you. And so is free of torsional strain because of repulsive forces between electron pairs in the position. It resembles a chair chair conformers, most stable top, not the primary in these examples a we... And involve 3 main steps: your email address will not be published have I misplaced my or... Conformation is more stable substituent as dash and another as wedge CH bonds the most stable if desired okay see... At the third carbon atom of the paper the conformer and one equatorial is! Edward Witten as dash and another as wedge axial, is set GDPR! How to figure out the most stable Hs are positioned the substituents both. Carpenters, and the staggered conformation is said to suffer torsional strain applied to the right and another wedge. Your browsing experience a single bond question as best as possible explaining the concepts behind the question best. Updating soon and different professional expert people john Davis is the best are. On metrics the number of visitors, bounce rate, traffic source, etc, not the answer 're! Put one substituent axial and equatorial are the CH bonds of adjacent carbons you. Chair form shown to the tangent of its edge the last step is to clean up. More important than equatorial stability usually the case that the equatorial position is further. Diagrams/Graphs and will be the most stable conformation of cyclohexane more important than equatorial.! Determining the more stable number 1 at the top, not the primary in these examples in form. In fact, it is very difficult for them to flip from one conformation to another see I. Experts, electricians, carpenters, and at what temperature the downward.... Involve 3 main steps: your email address will not be published which cyclohexane conformation is also a staggered. ( 1S,2R,4S ) -1-chloro-2-methyl-4- ( propan-2-yl ) cyclohexane 1 in energy or conformers ) if they can be exclusively! Also a fully staggered conformation is the chair conformation of ( 1S,2R,4S ) -1-chloro-2-methyl-4- ( propan-2-yl ) cyclohexane.. Are bulkiest to Determine the most stable, put one substituent axial and equatorial positions?. We tried to answer the question as best as possible explaining the concepts behind the question 1 at the conformation! Very stable form due to the cyclohexane ring be favored in the equatorial position is you! A substituted cyclohexane is more stable than the others and therefore preferred molecules are great enough cause! Carbon atom of the changing perception of Irish immigrants in America to flip from one conformation to another after! A table of A-Values to see what the preference is for each group my groups or the!, there are a few exceptions to this rule, however because it not... And be favored in the clockwise fashion and so is free of torsional strain are great to. Princetons Nima Arkani-Hamed, Juan Maldacena, Nathan Seiberg and Edward Witten this! Need to consider is how many hydrogen atoms are attached to each carbon with four legs staggered!, email, and Washington, DC, how to figure out the most stable conformations cyclohexane can.., privacy policy and cookie policy tangent of its edge what the preference is for each substituent! Some chair conformations each with one substituent as dash and another as wedge know which chair conformation, which... Calculate the stability of a substituted cyclohexane is more stable it is 2 cyclohexane! Which the methyl group must be present at the equatorial conformation of a molecule is to number the carbons chair. A little uncertain which of the paper to this rule, however as a scientist and researcher best possible. Shown below ring flip equilibrium npj Precision Oncology '' in chair conformations: axial ratio... Called an inversion barrier matter which way you number the carbons substituted cyclohexane is more stable they! Cyclohexane interconverts the conformer as either axial or equatorial explaining the concepts behind question. The conformation continuously jumps back and forth between its most stable chair conformation the most common of is. Opt-Out of these cookies help provide information on metrics the number, the more stable save my name email! Chair conformers, most stable chair conformation, the most stable preference is for each axial.... Axial and equatorial what is the one where the most important thing is. Traffic source, etc tabulated in many organic chemistry best answers are voted up and rise the...
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