Stereoisomer by SABRINA BINTI SOLOI -

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WONG LI XUAN ( BS17110324 )

2017-09-25 15:24:20 UTC

- 1-ethyl-3-sec-butyl cyclohexane has two substituents which are ethyl group and sec-butyl group.
- In the structure of the cis-1-ethyl-3-sec-butyl cyclohexane, both substituents are in the equatorial positions in one conformer and in axial positions in the other conformer.
- The conformer with both substituents in equatorial position is more stable than that in axial positions.
- This is because of both substituents have more room, therefore, fewer steric interactions when in the equatorial position.
- In the structure of the trans-1-ethyl-3-sec-butyl cyclohexane, both conformers have one substituent in an equatorial position and the other in an axial position.
- The sec-butyl group on a cyclohexane ring is large than the ethyl group on a cyclohexane ring.
- When the sec-butyl group is in the axial position, the 1,3-diaxial interactions will be stronger and cause the sec-butyl group in the axial position become less stable.
- The conformer with the sec-butyl group in equatorial position is more stable.

ILEN JAIBAD, BS17110123

2017-09-26 05:34:24 UTC

Both substituents of the cis-1-ethyl-3-sec-butyl cyclohexane are in equatorial positions in one chain conformer and both are in axial positions in the other. The conformer with both substituents in equatorial position is more stable. This is because the substituents has more room (space), away from the rest of the molecule and therefore fewer steric interactions.
Both chair conformers of the trans-1-ethyl-3-sec-butyl cyclohexane have one substituent in an equatorial position and the other in an axial position. Because the sec-butyl group is larger than the ethyl group, the 1,3-diaxial interactions will be stronger when sec-butyl group is in axial position. However the sec-butyl group is in equatorial position.Therefore it is more stable when compared to axial position.
Hence, whether the molecule is in cis or trans isomer, the one with the equatorial position will be more stable.

MOHD ZULKHAIRUL FIKRI BIN SAIDI (BS17110111)

2017-09-26 17:57:29 UTC

In 1-ethyl-3-sec-butyl cyclohexane, both substituents of the cis isomers are in the equatorial positions in one chair conformer and both are in axial positions in the other.

However, in trans isomer, one substituents in an equatorial position and the other in an axial. The sec-butyl group is larger than the ethyl group thus making it having stronger 1,3 diaxial interaction if it is on the axial position. So, the conformer that has the sec-butyl group in equatorial group is more stable.

Hence, the cis isomer is the more stable isomer in this case as both of its substituents is in equatorial position making it having less the 1,3 diaxial interaction.

LIYANA ZAFFIRAH BT ABD WAHAB (BS17110133)

liyanazaffirah96 — 2017-09-27 10:38:54 UTC

- In cis-1-ethyl-3-sec-butylcyclohexane , both substituents are in equatorial position in one chair conformer and both are in axial position in the other.
- If both substituents in equatorial position, it is more stable than in axial position.
- In trans-1-ethyl-3-sec-butylcyclohexane, both conformer have one substituents are in equatorial position and other in axial position.
-Since sec-butyl group is larger than ethyl group, the 1,3- diaxial interaction will be stronger if sec-butyl group is in axial position.
-Thus , conformer that has sec-butyl in axial position will be less stable.
- While conformer that has sec-butyl in equatorial position is more stable.

FOO JUN KANG (BS17110277)

foojunkang — 2017-09-27 11:44:12 UTC

There are 3 possible structure of 1-ethyl-3-sec-butyl cyclohexane as shown in the figure below, structure A, B, and C.
The most stable structure is structure C. The stability of the structures increase as ABoth of the substituents in structure C are in the equatorial position, this greatly reduce the 1,3-diaxial interaction, making it the most stable conformer among the three possible structures.

NURFAHMEE AIMAN HAKEEM BINTI NAZEER (BS17110095)

2017-09-27 12:36:07 UTC

In cis-1-ethyl-3-sec-butyl cyclohexane, both substituents are in equatorial positions in one conformer and the other is in axial positions.When substituents are in axial position, the interactions with other axial atoms on the same side tends to be more unfavourable. These unfavourable interactions are called 1,3-diaxial interactions.
When substituents are in the equatorial position, they are farther away from each other.Thus,this increases the stability of the conformation.

In trans-1-ethyl-3-sec-butyl cyclohexane,one substituents are in equatorial position and one substituents are in axial positions.The 1,3-diaxial interaction is stronger in axial positions because sec-butyl group is larger than ethyl group.Hence,cis isomer is more stable because the substituents are in equatorial positions.

CHAI WEN YAN (BS17110391)

2017-09-27 14:07:05 UTC

For the chair conformers of 1-ethyl-3-sec-butyl cyclohexane :
1. cis-1-ethyl-3-sec-butyl cyclohexane
The chair conformer with both substituents which is CH2CH3 and CH3CH(CH3)2 located in equitorial position will have a lower potential energy compare to the chair conformer with substituents located at axial position due to less steric interaction between the substituents. Therefore, it's more stable.
2. trans-1-ethyl-3-sec-butyl cyclohexane
The chair conformer with sec-butyl at equitorial position and ethly at axial position will be more stable than the conformer with sec-butyl at the axial position. This is because sec-butyl has a larger size compare with ethyl, as this will lead to a stronger 1,3-diaxial interaction when sec-butyl located at axial position and the conformer become less stable.
3. When compare the more stable conformer of cis-1-ethyl-3-sec-butyl cyclohexane and trans-1-ethyl-3-sec-butyl cyclohexane,
the most stable chair conformer will be the cis-1-ethyl-3-sec-butyl cyclohexane with both substituents at equitorial position as it consists of lowest potential energy among these chair conformers.

SCHOLISTICA DAYANA JOHNODI BS17110216

2017-09-27 14:23:30 UTC

A is more stable than B because of the 1,3-diaxial interaction. This is because one substituent in equatorial position and another one in axial position. Thus, it makes A more stable.
C is more stable than D because both substituents are in equatorial position. Thus, it is more stable when both substituents in equatorial

NUR AMIRAH ARINAH MOHD DEWA- BS17110379

amirawr_dewa — 2017-09-27 14:24:42 UTC

For cis-1-etyhl-3-sec-butyl, both substituents are at the equatorial position. Conformer with both substituents at the equatorial position is more stable than that at axial positions. Steric acid is less when in equatorial position. Whereas for trans-1-etyhl-3-sec-butyl, the conformer has one substituent at the equatorial and the other one is at the axial. Since sec-butyl group is larger than ethyl group, the 1,3 diaxial interaction will be stronger if it at the axial position. So, the conformer that has sec-butyl group is more stable.

Carlson egol BS17110136

2017-09-27 15:00:17 UTC

The chair conformer in cis isomer with both subtituent in equatorial position is the most stable while chair conformer with both subtituent in axial position has 1,3-diaxial interaction,make it less stable.
The chair conformer in trans isomer have one subtituent in equatorial position and axial position.Sec butyl group is larger than ethyl ,the 1,3 diaxial interaction is stronger in axial group make the confomer less stable compare to in equatorial position.

MELISA YACOB BS17110275

2017-09-27 16:56:16 UTC

For cis-1-ethyl-3-sec-butyl cyclohexane, I is more stable than II. This is because both CH2CH3 and CH3CH(CH3)2 located in equatorial position.
For trans-1-ethyl-3-sec-butyl cyclohexane, III is more stable than IV. This is because III has 1,3 diaxial interaction between CH2CH3 and CH3CH(CH3)2 which will be greater interaction between CH2CH3 and H and CH3CH(CH3)2 and H.

NADIAH BINTI NAHASIN(BS17110092)

2017-09-28 09:53:34 UTC

The molecule of 1-ethyl-3-sec-butyl cyclohexane has 2 different substituent which are ethyl and sec- butyl. For the cis-1-ethyl-3-sec-butyl cyclohexane, both of the substituent are located at the equatorial position in one chair conformer while on the other chair conformer, both substituents are located at the axial position. The structure where both substituent are at the equatorial position is more stable because there are more space or room between the substituent. Therefore, the steric interaction become fewer.
As for the trans-1-ethyl-3-sec-butyl cyclohexane, both of the substituent on each of the chair conformer are located at the equatorial and axial positions respectively. However, the chair conformer where the sec- butyl group is located at the axial position is less stable. This is because, the sec-butyl group is larger than the ethyl group causes the 1,3-diaxial interaction to be stronger. In other word, the chair conformer where the sec-butyl group is at the equatorial position is more stable.

IRENE TIAN CHOW CHENG ( BS17110304 )

2017-09-28 10:07:31 UTC

1) In cis-1-ethyl-3-sec-butyl cyclohexane, the structure on the left is more stable than the right structure.
- This is because the both substituents are in equatorial position in one chair conformer whereas for the structure on the right shows that both substituents are in axial positions.
- When substituents are in equatorial position, they are farther away from each other. This increase the stability of the conformation.
- When substituents are in axial position, there are more 1,3-diaxial interactions.

2) In trans-1-ethyl-3-sec-butyl cyclohexane, both structure have one subtituent in equatorial position and axial position.
- Sec-butyl group is larger than ethyl group.
- The large sec-butyl group which is in equatorial position is more stable than in axial position.
- The 1,3-diaxial interactions will be stronger when the sec-butyl group is in axial position. Therefore, the chair conformer structure on the left is more stable than the chair conformer on the right because the sec-butyl group is in equatorial positions.

2017-09-28 10:10:24 UTC

Both cis-1-ethyl-3-sec-butylcyclohexane isomers are in the equatorial positins in one chain conformer.Both substituents are also in axial position in each other.
These refer to the substituents have more spaces between molecule that fewer the steric interactions.

For trans-1-ethyl-3-sec-butylcyclohexane, the equatorial and axial positions not same. One substituent are in equatorial position while one substituent are in axial position.

Hence, cis-1-ehtyl-3-sec-butylcyclohexane are more stable than trans-1-ethyl-3-sec-butylcyclohexane isomers.

GAN LI YUN BS17110405

2017-09-28 10:33:05 UTC

-In cis-1-ethyl-3-sec-butylcyclohexane, the chair conformer of cis isomer with both substituents in equatorial position is more stable.
-This is because the substituents have more room and fewer steric interaction.
-For chair conformer of cis isomer with both substituents in axial position, there are two 1,3-diaxial interactions which causes it to be less stable.
-In trans-1-ethyl-3-sec-butylcyclohexane, both chair conformer of trans isomers have one substituent in axial position and another in equatorial position.
-However, the chair conformer of trans isomer with larger substituent [sec butyl grouo] is less stable because the 1,3-diaxial interaction is more stronger than that of smaller substituent [ethyl group] in another chair conformer.

YEAK WEEN JUN BS17110356

2017-09-28 10:56:48 UTC

The chair conformer for 1-ethyl-3-sec-butyl-cyclohexane have two substituent that is ethyl and sec-butyl substituent.

For cis-1-ethyl-3-sec-butyl-cyclohexane, both substituents of the cis-isomer are in equatorial position in one chair conformer and both are in axial position in the other chair conformer . The chair conformer with both substituent in equatorial positions is more stable because the substituent have more room therefore fewer steric interactions. The chair conformer in axial position is less stable due to 1,3-diaxial interactions which the axial substituents are close and parallel to each other that provide less room between each other causes their electron clouds have much energy to repel each other.

For trans-1-ethyl-3-sec-butyl-cyclohexane, both the chair conformer have one substituent in an equatorial position and the other in an axial position. Because the sec-butyl group is larger than ethyl group, the 1,3-diaxial interactions will be stronger when the sec-butyl group is in an axial positions. Therefore the conformer with sec-butyl group in an equatorial position is more stable.

Compare the more stable chair conformer in cis-1-ethyl-3-sec-butyl-cyclohexane and in trans-1-ethyl -3-sec-butyl-cyclohexane, I conclude that the the most stable chair conformer is cis-1-ethyl-3-sec-butyl-cyclohexane.Because both of the substituent are in equatorial position which are more room and fewer steric interactions compare to those substituents in axial position which is close to each other and have stronger 1,3-diaxial interactions.

SU LIAN CHYN BS17110270

2017-09-28 11:08:56 UTC

The most stable conformer is trans-1-ethyl-3-sec-butylcyclohexane
-Sec-butyl group is larger than ethyl group.
-Larger sec-butyl group in an equatorial position result in more stable conformer.
-In cyclohexane, the equatorial position is energetically favored over the axial position.
-Substituents in axial position will experience stronger "1,3-diaxial interactions".
-Since the two substituents on both the cis-1-ethyl-3-sec-butylcyclohexane and trans-1-ethyl-3-sec-butylcyclohexane are on the same side of the ring, one in an equatorial position and the other in axial position is more stable.
-So,trans-1-ethyl-3-sec-butylcyclohexane is the most stable.

MUHAMMAD ANAS HAFIZ BIN NUSRI (BS17110389)

2017-09-28 11:50:17 UTC

*In cis-1-ethyl-3-sec-butylcyclohexane, the chair conformers of cis isomer with both substituents in equatorial position, it is more stable than in axial position.
*In trans-1-1-ethyl-3-secbutylcyclohexane, both conformers have one substituents in equatorial position and other in axial position.
*Then, the 1,3-diaxial interaction is stronger in axial position because sec-butyl group is large than ethyl group.

SITI NOORAMIRFA BINTI AMIR (BS17110131)

2017-09-28 12:07:08 UTC

SITI NOORAMIRFA BINTI AMIR (BS17110131)

cis-1-ethyl-3-sec-butylcyclohexane
-The most stable conformer is when both substituents are in the equatorial position compared to that both substituents in the axial position. This is because when substituents are in equatorial position,the substituents is far from each other and thus have more room and less steric interaction. When both substituents are in the axial position, there are more 1,3-diaxial interaction .Thus,it is a less stable chair conformer.

trans-1-ethyl-3-sec-butylcyclohexane
-Both structure have one substituent in equatorial position and one in axial position. In this case, it is depends on the size of the substituents attached. Sec-butyl group is larger than ethyl group. It is more stable when the large sec-butyl group is in the equatorial position than in axial position. This is because when the sec-butyl in the axial position, 1,3-diaxial interaction will be stronger. Therefore,the chair conformer is less stable.

SITI NURFAIHANNA KASIMIN (BS17110208)

2017-09-28 12:09:22 UTC

1-ethyl-3-sec-butylcyclohexane has two structure chair conformers that are cis-1-ethyl-3-sec-butylcyclohexane and trans-1-ethyl-3-sec-butylcyclohexane.

The conformers with cis-1-ethyl-3-sec-butylcyclohexane, both substituents of it are in equatorial positions in one chair conformers, and both are in axial positions in the other. The conformer with both substituents in equatorial position is more stable.

While for the conformers trans-1-ethyl-3-sec-butylcyclohexane, both have one substituent in an equatorial position and the other in an axial position. Because the sec-butyl group is larger than the ethyl group, the 1,3-diaxial interactions will be stronger when sec-butyl group is in an axial position. Therefore, the conformer with the ter-butyl group in an equatorial position is more stable.

Lee Fui San (BS17110374)

2017-09-28 13:20:14 UTC

1. cis-1-ethyl-3-sec-butylcyclohexane
- Both substituents of the cis isomer are in equatorial positions in one conformer and in axial positions in the other conformer.
- The conformer with both substituents in equatorial positions is more stable because substituents have more room and, therefore, fewer steric interactions.
2. trans-1-ethyl-3-sec-butylcyclohexane
- Both conformers of the trans isomer have one substituent in an equatorial position and the other in an axial position.
- The sec-butyl group is larger than the ethyl group, the 1,3-diaxial interactions will be stronger when the sec-butyl group is in the axial position.
- Therefore, the conformer with the sec-butyl group in the equatorial position is more stable.

ANGIE TAN FUI JIE (BS17110373)

2017-09-28 13:35:13 UTC

When substituents are in axial position, there tends to be more unfavourable interactions called 1,3-diaxial interactions with other axial atom on the same side.
That's why substituents prefer to be in the equatorial position as the substituents are farther away from each other and this increase the stability of conformation.
- So, for the cis isomer, the conformer that both substituents are in equatorial positions is more stable than the other conformer that both substituents are in axial position.
- As for the trans isomer, both conformers have one substituent in an equatorial position and the other substituent in an axial position. The conformer with the sec-butyl group in the equatorial position is more stable because the sec-butyl group is larger than the ethyl group, hence the 1,3-diaxial interactions will be stronger when the sec-butyl group is in the axial position.
The larger the group of substituent is, the more it will tend to remain in the equatorial position.
- In my opinion, the cis-1-ethyl-3-sec-butylcyclohexane conformer with both substituents in the equatorial position is the most stable conformer as there's not much unfavourable interaction, substituents have more room, and therefore, fewer steric hindrance.

EMMA SYAFINAH BINTI ARIFFIN (BS16110082)

2017-09-28 13:36:57 UTC

-In cis-1-ethyl-3-sec-butylcyclohexane, the conformer on the left is more stable than the right.

-This is because the conformer on the left has both of the substituents in the equatorial position whereas the conformer on the right has both of the substituents in the axial position.

-The conformer with both of its substituents in the equatorial position is more stable because the substituents have more room and fewer steric interactions.

-In trans-1-ethyl-3-sec-butylcyclohexane, both conformers have substituent in the axial and equatorial position.

-The conformer on the left is more stable because the sec-butyl group is in the equatorial position while in the right conformer it is in the axial position.

FATINAH BINTI GHADAFI(BS17110245)

2017-09-28 13:39:48 UTC

- The chair conformer in cis-1-ethyl-3-sec-butyl cyclohexane have both substituents in equatorial position that have more room and less steric interaction and make it more stable than substituents in axial position which has 1,3 diaxial interaction.
- While in trans-1-ethyl-3-sec-butyl cyclohexane , both conformers have one substituent in equatorial position and axial position. Sec butyl is larger than ethyl group. The 1,3 diaxial interaction is stronger in axial position make the conformer less stable compare to in equatorial position.

MOHD FAZI DE BIN SAM (BS17110320)

youlol98 — 2017-09-28 13:48:58 UTC

- cis-1-ethyl-3-secbutylcyclohexane is the most stable structure for chair conformer is because both substituents are placed in the equatorial position

-when both substituent is placed on axial position, 1,3-diaxial interaction will occur which the hydrogen will interact with the bulkyl group that is placed on the axial position, making it more unstable

-trans-1-ethyl-3-secbutylcyclohexane has the second most stable structure is because the more bulkyl group which is sec butyl is placed on the equatorial position rather than on the axial postion

-sec butyl substituent is placed on the equatorial position is to avoid 1,3-diaxial interaction from occuring

Low Wei Yee (BS17110352)

2017-09-28 14:12:30 UTC

Among the four possible chair conformer, the most stable chair conformer will be cis-1-ethyl-3-sec-butyl cyclohexane with both substituents are in equatorial positions.

When both substituent located at equatorial, there will be more room and away from other molecules, therefore, fewer steric interaction.

It also minimize 1,3-diaxial interaction where hydrogen or substituent interact with each other to produce unfavorable steric reaction. In contrast, the cis-1-ethyl-3-sec-butyl cyclohexane is less stable as both substituent locates at axial positions, that lead to 1,3-diaxial interaction to be occur.

It is more stable than trans-1-ethyl-3-sec-butylcyclohexane because of the presence of substituent located at axial position that may lead to 1,3-diaxial interaction in trans-1-ethyl-3-sec-butylcyclohexane structure.

MARCOLLETE BINTI MADATO (BS17110144

2017-09-28 14:17:56 UTC

-Cis-1-ethyl-3-sec-butyl cyclohexane is the most stable conformer with both substituent are both as equatorial group.

-It is because it has 2 equatorial groups compared to 1 equatorial group in trans-1-ethyl-3-sec-butyl cyclohexane.

-2 equatorial groups is more stable than 1 equatorial group.

-2 equatorial group have lower energy thus more stable while 1 equatorial group have higher energy thus less stable.

-Cis-1-ethyl-3-sec-butyl cyclohexane with both substituent in equatorial position is more stable than both substituent in axial position because when both substituent are in equatorial position,they are farther away from each other thus increase the stability of the conformation.

Tsong Jia Ling (BS17110261)

2017-09-28 14:23:38 UTC

1) Cis-1-ethyl-3-sec- butyl cyclohexane

- Cis-1-ethyl-3-sec-butyl cyclohexane has 2 structures : the first structure is both substituent in equatorial position and the second structure is both substituent in axial position.

- The conformer with both substituents in equatorial position is stable than both in axial position.

- This is because the substituents in equatorial position have more room,therefore less steric interaction.

2) Trans-1-ethyl-3-sec- butyl cyclohexane

- Both conformers of the trans-1-ethyl-3-sec-butyl cyclohexane have one substituent in axial position and the other in equatorial position.

- Conformer with sec-butyl group in the equatorial position is more stable because the sec-butyl group is larger than ethyl group, the 1,3-diaxial interaction will be stronger when sec-butyl is in axial position.

Haerun Nisa Binti Baharudin (BS17110288)

2017-09-28 14:39:27 UTC

*In cis-1-ethyl-3-sec-butylcyclohexane,the chair conformer has substituent at equatorial and axial position.the substituents in an equatorial position is more stable one because it has more room and steric interaction when it is in an equatorial position.

*while for trans-1-ethyl-3-sec-butyl cyclohexane,the chair confomer also have substituents at equatorial and axial position.sec-butyl group is larger than ethyl group.sec-butyl will be stable if it in the equatorial position due to 1,3-diaxial interaction which is stronger.

Nurul Asma binti Razali (BS17110326

2017-09-28 15:14:18 UTC

As for the cis-1-ethyl-3-sec-butyl cyclohexane, structure B is more stable compare to structure A because the substituent in structure B is located at the equatorial position and lesser steric interaction occured.

Whereas for the trans-1-ethyl-3-sec-butyl cyclohexane, structure D is more stable because the prioritized sec-butyl substituent is located at the equatorial position of structure D, while the sec-butyl substituent in structure C is located at the axial position. Thus, stronger steric interaction occurs.

Rabiatul Adawiyah Binti Suwandi (BS17110106

2017-09-28 15:27:42 UTC

Chair Conformer no.1 for both cis-1-ethyl-3-sec-butylcyclohexane and trans-1-ethyl-3-sec-butylcyclohexane is more stable.

Because the chair conformer with a substituent in the equatorial position is more stable, also because there is more room and less steric strain, in an equatorial position.
A substituent in an axial position are more unfavorable 1,3-diaxial interactions.

EVANGELINE YVONNE STIDI (BS17110282)

2017-09-28 15:36:15 UTC

•1-ethyl-3-sec-butyl cyclohexane has 2 substituents which are ethyl and sec-butyl.
•Sec-butyl is larger in size than ethyl.
•1,3-diaxial interaction is greater with sec-butyl.
•Molecule exists in more stable conformation with sec-butyl in the equatorial position.
•When the chair conformation has the larger groups in equatorial position, it is more stable.

NURFARHANA FATIN BINTI MOHD YASSIN(BS17110231)

2017-09-28 15:58:45 UTC

Trans-1-ethyl-3-sec buty cyclohexane
the structure B more stable because the sec butyl substituent located at the equatorial position. But in A , it is located at the axial position. When the sec butyl which is bukyl group near with the other substituent it will make the steric interaction become more stronger. in structure B. both of the substituent are far from each other , the lesser steric interaction. and the structure will be more stable.

Cis - 1 - ethyl - 3 - sec butyl cyclohexane
the structure of C is less stable than D because the both of the subsituent is located at the axial position. which is will make stronger steric interaction. When the steric interaction is stronger , the structure will be unstable. but in D , the sec butyl located at the axial position and ethyl at the equatorial. It reduces the steric interaction. thus make it become stable.

HOLLYSIUS JR JULIN (BS17110230

2017-09-28 16:12:16 UTC

1.cis-1-ethyl-3-sec-butyl cyclohexane

Both conformer have the substituent in an equatorial position .
Conformer A is more stable than conformer B. This is because the substituents in conformer A are in an equatorial position which make it more stable because of the substituent has more room and away from other molecule which means that the steric effect is lower. Conformer B is less stable because the substituents are in an axial position. This is because the interacting axial substituents tend to be unfavorable by steric interaction that called 1,3-diaxial interaction.

2.trans-1-ethyl-3-sec-butyl cyclohexane

Both conformer have substituent in an equatorial and axial position.
Conformer C is more stable than conformer D. This is because the conformer is more stable when the sec butyl group in an equatorial position because sec butyl group is larger than ethyl group.

JOANNE LIM CHIA PEI (BS17110280)

2017-09-28 16:25:10 UTC

1.The left chair conformer of cis-1-ethyl-3-sec-butyl cyclohexane is more stable than the right. This is due to the both substituents located in equatorial, therefore more room or less steric effect is experienced.
2.The left chair conformer of trans-1-ethyl-3-sec-butyl cyclohexane is more stable because the sec-butyl group is larger than ethyl group. Sec-butyl group experienced stronger 1,2 diaxial interactions in axial group.Therefore it is more stable in equatorial.

NURAZRIENAH AZRIEAMAH BT JAKARIAH, BS17110392

nurazrienahazrieamah — 2017-09-28 17:19:07 UTC

*The structure name 1-ethyl-3-sec-butylcyclohexane have two substituents which is sec-butyl and methyl group.
*This structure have two possible chain conformer which are cis-1-ethyl-3-sec-butylcyclohexane and trans-1-ethyl-3-sec-butylcyclohexane.
*Both substituent that are sec-butyl and metyhl group placed in equatorial position, which make it energitically favoured over the axial position.
*The sec-butyl group is larger than methyl group and therefore, the tendency to remain in the equatorial position is higher.
*This cause the increasing in the stability of the conformer.
*Hence, cis-1-ethyl-3-sec-butylcyclohexane is the most stable conformer compare to trans-1-ethyl-3-sec-butylcyclohexane for structure name 1-ethyl-3-sec-butylcyclohexane.

Nur Athira Zahira Binti Mutahar (BS17110039

NurAthiraZahira — 2017-09-28 17:56:40 UTC

A 1-ethyl-3-sec–butyl cyclohexane compound has cis and trans stereoisomers. In addition, each of these stereoisomers has two possible chair conformations.

Firstly, a cis isomer for this compound can be either diequatorial cis-1-ethyl-3-sec-butyl cyclohexane (A) or diaxial cis-1-ethyl-3-sec-butyl cyclohexane (B). (A) is more stable conformer than (B) because steric interactions between ethyl and sec-butyl are minimized in (A) since both are located further away from each other. An axial ethyl group, however, is close to sec-butyl axial atoms, creating two destabilizing steric interactions called 1,3-diaxial interactions which destabilize a cyclohexane conformation.

Next, in a trans isomer one of the subtituent should be axial and the other is equatorial. However, the equatorial position has more room than the axial position, so larger substituents are more stable in the equatorial position. Therefore (C) is more stable compared to (D) since in (C) sec-butyl is equatorial while ethyl is axial.

After all, (A) is the most stable even when compared to (C) because (A) has a conformation with both subtituent groups equatorial which has more room and can reduce steric interaction between the substituents.

MAUREEN GRACE (BS17110341)

2017-09-28 19:56:11 UTC

1. cis-1-ethyl-3-sec-butyl cyclohexane
A cis isomer for this compound can either be diaxial cis-1-ethyl-3-sec-butyl cyclohexane which was labelled as (A) and diequatorial cis-1-ethyl-3-sec-butyl cyclohexane which was labelled as (B). (A) is more stable conformer compared to (B) because larger group which is the sec butyl group was placed on equatorial bond therefore have more room and less steric interaction.

2. trans-1-ethyl-3-sec-butyl cyclohexane
Both conformer have substituent both on equatorial and axial bonds. (C) is more stable conformer compared to (D) because the sec butyl group is on equatorial bond and also sec butyl group is a larger group compared to ethyl group.

Micklin Melson(BS17110401)

2017-09-28 21:54:57 UTC

In cis -1-ethyl-sec-butyl,the conformer on the left has one sec-butyl group in equatorial position while on the right in axial position. So, the conformer in the equatorial position is more stable.

Same thing goes to trans-1-ethyl-3-sec-butyl,the conformer on the right also has an equatorial position and that mean it's more stable from the conformer on the right.

This is because the sec-butyl group is larger than the ethyl group, the ,3-diaxial interaction will be stronger when the sec-butyl group is in an axial position. Therefore the conformer with sec-butyl group in equatorial position is more stable.

2017-09-29 02:19:03 UTC

*BS17110225*
*SITI NABILAH BINTI AWANG RABLAH*

•1-ethyl-3-sec-butylcyclohexane has 2 substituent which are ethyl group and sec-butyl group.
•substituents that are in equatorial position are more stable than axial position.
• In cis-1-ethyl-3-sec-butylcyclohexane the substituents that are placed in equatorial position have more space. thus, less steric interaction.
• In Trans-1-ethyl-3-sec-butylcyclohexane the the bigger the space, more steric interaction.

MUHAMMAD ZAIM ANAQI BIN ZAIMEE (BS17110051)

2017-09-29 02:54:56 UTC

•Compound: 1-ethyl-3-sec-butyl cyclohexane

If the cyclohexane ring has two subtituents, we must take both substituents into account when predicting which of the two chair conformers is more stable. Therefore, we are going to use "cis" and "trans" isomer to determine the more stable conformer;

1."cis"-1-ethyl-sec-butyl-cyclohexane
Based on the drawing, conformer A has both of its subtituents on the axial positions while conformer (B) has both of its subtituents on the equatorial positions. (B) is more stable because conformer that have all of substituents on the equatorial positions will have more room and is far from the other molecules. It also minimise the 1,3-diaxial interaction where substituents interact with each other to produce unfavorable steric reaction. Therefore, the conformer with both substituents on the equatorial position is more stable which is conformer (B)

2."trans"-1-ethyl-3-sec-butyl cyclohexane
Based on the drawing also, both chair conformers of the trans isomer have one substituent in an equatorial positions and the other in an axial position. Because the sec-butyl group is larger than the ethyl group, the 1,3-diaxial interaction will be stronger when the sec-butyl group is an axial position. Therefore, the conformer with the sec-butyl group in an equatorial is more stable which is conformer (C)

As conclusion, conformer (B) is the most stable than the other 3 is because both substituents are in equatorial positions because of the fewer 1,3-diaxial interaction between the substituents

Ahmad Nor Asyraf Bin Azman BS17110286

2017-09-29 03:11:18 UTC

1) For cis-1-ethyl-3-sec-butylcyclohexane,both substituents can be either at diaxial position or diequatorial position.The chair conformer in cis isomer with both substituents in equatorial position is more stable than when both substituents at axial position.

2) For trans-1-ethyl-3-sec-butylcyclohexane both substituents are in different position which is one at the axial position and the other one at the equatorial position.
Sec-butyl group is larger than ethyl.So when larger group at the equatorial position thus it become more stable than at axial.Therefore, 1,3 diaxial interaction will be stronger when sec-butyl group is in an axial position and make it less stable.

MELVINDO JACOB (BS17110337)

2017-09-29 03:13:39 UTC

1-ethyl-3-sec butyl cyclohexane has two substituents which are sec-butyl group and ethyl group. In structure of the cis-1-ethyl-3-sec butyl cyclohexane. Both substituents are in axial in one conformer and in the equatorial in other conformer.

The conformer with both substituents in equatorial is more stable than in axial positions. There are more space,therefore fewer steric interactions occur when in equatorial.

In the structure of trans-1-ethyl-3-sec butyl cyclohexane, both conformers are have one substituent in equatorial and other in axial position. Cyclohexane ring has sec-butyl group which is larger than ethyl group. Because the sec-butyl group is larger than the ethyl group, the 1,3 diaxial interactions will be stronger when the sec-butyl group is in axial position. Therefore, the conformer with the sec-butyl group in equatorial position is more stable.

MUHAMMAD ZAIM ANAQI BIN ZAIMEE (BS17110051)

2017-09-29 03:18:58 UTC

MAISARAH BINTI ABDULLAH BS17110043

2017-09-29 03:48:43 UTC

2For cis-1-ethyl-3-sec-butyl cyclohexane, the ethyl group and the sec-butyl group are in the equatorial position in conformer B and in the axial positions in conformer A. conformer B is more stable than conformer A because the large distance between these two substituents prevent the steric interaction from occur while in conformer B the two substituents were nearly closed and This will create two steric interactions which is 1,3-diaxial interactions and causes the cyclohexane ring unstable.

Meanwhile for trans-1-ethyl-sec-butyl cyclohexane, the ethyl group is in axial positions while the sec-butyl group is in the equatorial positions. But trans-1-ethyl-sec-butyl cyclohexane is less stable than cis-1-ethyl-3-sec-butyl cyclohexane because of the distance between two substituents. So it means that trans-1-ethyl-sec-butyl cyclohexane have stronger 1,3-diaxial interactions than cis-1-ethyl-sec-butyl cyclohexane .

Conclusion: Cis-1-ethyl-3-sec-butyl cyclohexane is more stable than trans-1-ethyl-3-sec-butyl cyclohexane

JOANN KOH HUI XIAN BS17110394

bs17110394 — 2017-09-29 03:52:10 UTC

There are 2 substituents found in 1-ethyl-3-sec-butyl cyclohexane,which are ethyl and sec-butyl substituent.Since 1-ethyl-3-sec-butyl cyclohexane has two substituents,we can use CIS and Trans to compare which of the chair conformer is more stable.

For Cis-1-ethyl-3-sec-butyl cyclohexane,both substituent are located in an equatorial position in the conformer on right hand side.For the left hand side,both substituent in 1-ethyl-3-sec-butyl cyclohexane are found in an axial position.The conformer with substituent in an equatorial position is more stable than the conformer that substituent located in an axial position,because in the equatorial position has more room and cause the other molecules being further from them,therefore fewer 1,3-diaxial interactions between them.

For Trans-1-ethyl-3-sec-butyl cyclohexane,both of the chain conformer had ome substituent in an equatorial position and the other in an axial position.The sec-butyl group is larger than the ethyl group,the 1,3-diaxial interaction will be stronger when the sec-butyl group in axial position.Therefore, the conformer with the sec-butyl group in an equatorial position is more stable.

When we compare the stability between cis-1-ethyl-3-sec-butyl cyclohexane and trans-1-ethyl-3-sec-butyl cyclohexane,can be conclude that cis-1-ethyl-3-sec-butyl cyclohexane is the most stable chair conformer.This is because both substituent are located in an equatorial position and fewer 1,3-diaxial interactions between them.

Nurul Najiha Binti Datu Masjidin

2017-09-29 04:08:42 UTC

BS17110305

-1-ethyl-3-sec-butyl cyclohexane has 2 substituents which are ethyl and sec butyl. At the structure of cis-1-ethyl-3-sec-butyl cyclohexane, both of the substituent is placed on the axial position in one chain conformer and an on equatorial at the other conformer. A is more stable due to the substituent located at equitorial position which causes less steric interactions.
- As for the trans-1-ethyl-3-sec-butyl cyclohexane, both conformers have one substituent on equatorial position and the other on axial position. thus, structure C more is stable than D as the sec-butyl group is placed on the equatorial position.

NUR WAZIRA HUSNA BINTI MOHD WAZIR (BS17110249)

2017-09-29 04:17:17 UTC

I choose cis-1-ethyl-3-sec-butylcyclohexane with both substituents in equatorial position as the most stable.
1. Trans isomer both have one substituent in an equatorial position and the other on axial. The sec-butyl group is larger than ethyl group, the 1,3-diaxial interaction will be stronger when sec-butyl group is in the axial position. Therefore, the trans conformer with sec-butyl group in the equatorial position is more stable.
2. But compare to cis isomer , both substituents is in equatorial position which is more stable than trans isomer.
So, the conclusion is cis isomer with both substituents in equatorial position is the most stable.

NOR AZMIMI BINTI AMBATANG (BS17110338)

2017-09-29 04:21:29 UTC

ELIZA LEONG NYUK CHUI (BS17110168)

2017-09-29 04:32:52 UTC

In the structure cis-1-ethyl-3-sec-butyl cyclohexane both substituents are in the equatorial position in one conformer and in the other conformer both substituents are in axial position.
The conformer with both substituents in equatorial position is more stable than in axial position due to both substituents have more room thus, steric interactions is weak when in the equatorial position.
In the structure trans-1-ethyl-3-sec-butyl cyclohexane both conformer have one substituent in an equatorial position and the other in an axial position.
Because of sec-butyl group is larger than ethyl group, 1,3-diaxial interactions will be stronger when sec-butyl group is in an axial position. This cause the sec-butyl group in axial position become less stable.
Thus,the conformer with sec-butyl group in an equatorial position is more stable.

YUSDALIFAH BT TOH @YUNUS (BS17110250)

2017-09-29 04:45:24 UTC

For cis conformer which both substituent are in equaritorial position are the most stable conformer while for trans where both conformer have one substituent at equatorial position and axial position but sec-butyl have larger molecule than ethyl that makes 1,3-diaxial interaction stronger in axial position

JAIMAH BINTI GINTUANG ( BS17110217 )

2017-09-29 05:16:09 UTC

Both substituents of the cis-1-ethyl-3-sec-butyl cyclohexane are in the equatorial position and the other substituents are in the axial position. Equatorial bond is more stable than axial bond. So, the most stable chair conformer is the cis-1-ethyl-3-sec-butyl cyclohexane with the equatorial position.

One of the substituent in the trans-1-ethyl-3-sec-butyl cyclohexane is in the equatorial position(sec-butyl) and the other one is in the axial position(ethyl). While another chair conformer of trans-1-ethyl-3-sec-butyl cyclohexane is in the axial position(sec-butyl) and the other one is in the equatorial(ethyl). 1,3-diaxial interaction become stronger when it is in the sec-butyl substituent. It is because, the sec-butyl is big group compare to ethyl group. Since the equatorial bond is stronger than axial bond so, the most stable chair conformer is the sec-butyl substituent in the equatorial group.

Ezzah shafiqah binti Julhia BS17110041

2017-09-29 05:24:46 UTC

First of all, there are 4 possibles chair conformers that can be form from 1-ethyl-3-sec-butylcyclohexane.
1)cis-1-ethyl-3-sec-butylcyclohexane
In chair conformer A where the both of the substituents (ethyl and sec-butyl group) are located on the equatorial position while in chair conformer B the substituents are located in axial position.
Therefore, A is more stable due to the position of the substituents on the equatorial where Its lead to have more room for the substituents and less steric interaction will be form than isomer B.
2.Trans-1-ethyl-3-sec-butylcyclohexane
For isomer C , the position of the ethyl group is on equatorial position while the sec-butyl group is on axial position.Meanwhile, for the isomer D, the ethyl group is on the axial position while the sec-butyl group is on the equatorial position.
Therefore, because of isomer D has the largest group which is sec-butyl group in equatorial position, it is more stable than isomer C .This is because, the size of sec-butyl is larger than ethyl , which is lead to stronger 1,3- diaxial interaction due to the location of the sec butyl group at the axial position and its make the conformer less stable.
As a conclusion, between the chair conformer A and D, the most stable chair conformer is A due to the both of the substituents are located on the equatorial position than D where its on the sec butyl on the equatorial position.

Rozailin Binti Mohammed

2017-09-29 05:27:19 UTC

BS17110393
-There are 4 possible chair conformer for 1-ethyl-3-sec-butylcyclohexane
-For cis 1-ethyl-3-sec-butylcyclohexane, A is more stable than B
- both of subtituent located on the equatorial has more room and therefore fewer steric interactions
-For trans 1-ethyl-3-sec-butylcyclohexane, D is more stable than C
-for c and d, D isomer is more stable as the sec butyl group are in equatorial position.the, sec butyl has larger size compare with ethyl as this will lead to stronger 1,3- diaxial interaction when sec butyl located at axial position and the conformer become less stable.
lastly the isomer A is more stable than D because both of the substituents in the equatorial position than D.

MUHAMMAD FARIHIN BIN ABDUL WASIH

2017-09-29 05:27:48 UTC

BS17110382

There are four possible structure of the 1 -ethyl-sec-butyl cyclohexane that s cis-1-ethyl-3-sec-butyl cyclohexane and its ring flip structure and trans-1-ethyl-3-sec-butyl cyclohexane and its ring flipped structure .
The most stable structure is the cis-1-ethyl-3-sec-butyl cyclohexane with both of its substituent on the equaturioal position . This is because it has the lowest potential energy and has the less steric interaction . Thus , this make it the most stable strucutre between the four .

ETHEL EVELYN HIEW (BS17110099

2017-09-29 05:29:06 UTC

A. cis-1-ethyl-3-sec-buty

ETHEL EVELYN HIEW (BS17110099)

2017-09-29 05:35:36 UTC

Compound: 1 ethyl-3-sec-butylcyclohexane

A. cis-1-ethyl-3-sec-butylcyclohexane
*(1) is more stable than (2) due to both substituents located in equatorial position.

B. trans-1-ethyl-3-sec-butylcyclohexane
*(3) is more stable than (4) due to (3) has 1,3 diaxial interaction between CH2CH3 andCH3CH(CH3)2 which will be greater interaction between CH2CH3 and H and CH3CH(CH3)2 and H.

Nur Amira Binti Misah BS17110318

2017-09-29 05:38:46 UTC

Y1-ethyl-3-sec butyl cyclohexane in the structure 1 is more stable than the structure 2 because in the structure 1 1-ethyl-3-sec butyl cyclohexane in the equatorial position while in the structure 2 1-ethyl-3-sec butyl cyclohexane in the axial position. When the 1-ethyl-3-sec butyl cyclohexane in equatorial position, they are father away from each other cause low energy between they. This increase the stability of the conformer. While when 1-ethyl-3-sec butyl cyclohexane in the axial position, there tends to be more unfavorable interaction which have high energy between they. This decrease the stability of the conformation.

NATHAN JEREMIAH BS17110237

2017-09-29 05:54:43 UTC

for the cis one, the more stable chair is where the the CH2CH3 and CH(CH3)CH2CH3 are at the equatorial position
for the trans one, the more stable chair is where sec-butyl substituent is at the axial

NURUL ATIQAH binti ROBERT BS17110132

2017-09-29 05:59:15 UTC

Cis-1-ethyl-3-sec-butyl cyclohexane are in equatorial positions is less stable than axial positions

BS17110044 asyikin binti asri

2017-09-29 06:00:03 UTC

in cis-1-ethyl-3- sec-butylcyclohexane, A is more stable than B because of the substituent in equatorial position while in trans-1-ethyl-3-sec-butylcyclohexane, D is more stable than C because of sec-butyl substituent in equatorial position.

HUMAIRA FONG ZI LI (BS16110873)

2017-09-29 09:08:35 UTC

-the 1-ethyl-3-sec butyl cyclohexane chair conformer have 2 substituents that is ethyl and sec-butyl
-the conformer with both subsituent in equatorial positions is more stable
-the sec-butyl group is larger than methyl group, then the substituent in axial position will experience stronger 1,3-diaxial interactions
-causing it less stable than chair conformers with both in equatorial positions
-the larger the distance between the groups, the more stable the conformations
-a molecule will more stable if there are more attractive forces and less repulsive forces
-attractive forces lowers the potential energy of molecule
-and repulsive forces increases the potential energy of molecule, so molecule with lowers potential energy is more stable
-stearic effects lead to conformations in which repulsions are minimized, this lowers the potential energy of the molecule (more stable)
-because substituents have more room therefore fewer stearic interactions
-hence, the most stable ONE is trans-1-ethyl-3-sec butyl cyclohexane

SHEILA CASANDRA OLIVIA BINTI YAHADIN BS17110327

2017-09-29 13:34:56 UTC

In cis-1-ethyl-3-sec-butyl cyclohexane, the structure on the right is more stable because the substituent located at the equatorial position and lesser steric interaction
In trans-1-ethyl-3-sec-butyl cyclohexane, the structure on the right is more stable because the prioritized sec-butyl substituent is at equatorial position of the structure while sec-butyl substituent of structure on the left is at axial position. Therefore, the more greater the steric interaction

NOR RADZSHIELLA BINTI HASHIM BS17110349

2017-09-29 13:38:40 UTC

Cis-1-ethyl-3-butylcyclohexane, both substituent are in equatorials position in one chair conformers meanwhile on the other side both substituent are in the axial position.
When both substituent are in equatorial positions, they are more stable compared to the one with axial position.
Meanwhile, in trans-1-ethyl-3-butylcyclohexane, one substituent are in an axial positions in a chair conformers and on the other side, on one substituent are positioned in equatorial position.
The interaction known as 1,3-diaxial will be stronger if sec-butyl group are in axial position as ethyl group are smaller than sec-butyl group. Therefore, the conformers that contain sec-butyl in equatorial position are more stable than the one conformers that contain sec-butyl in axial position.

Velentdion Febi Manuil BS17110298

2017-12-03 11:21:44 UTC

•1-ethyl-3-sec-butylcyclohexne has two chair confomers
(I)cis-1-ethyl-3-sec-butylcyclohexane
(II)trans-1-ethyl-3-sec-butylcyclohexane
•an equtorial substituition is more stable than axial substituition.
•cis-1-ethyl-3-sec-butylcyclohexane,the substituents are both in equatorial position while one of it are in axial position.
•Trans 1-ethyl-3-sec-butylcyclohexane,the substuents are both in equatorial posistion while one of it are in axial position.But sec-butyl group is larger than ethyl group.so,1,3-diaxial interaction will be stronger in the sec-butyl group in axial interaction.
•Therefore,trans 1-ethyl-3-sec-butylcyclohexane is more stable.