LAPRAK HYDRO GROUP 5

PRACTICUM REPORT

CIS-TRANS AND E-Z GEOMETRY ISOMERS FOR ALKENA AND
NEWAMAN'S PROJECTION MOLECULAR MODEL IS ECLIPSED,

STAGERED AND ANTI-ZERO FOR N-BUTANE MOLECULES.

BY GROUP 5

NAME : 1. MIRANDA A.SIHITE (4203131031)
(4203131046)
2. MUTIARA PANCA PUTRI SINUHAJI (4203332025)

SUPPORTING LECTURER 3. NURUL AMALIAH NASUTION
COURSES : Dr.Marham Sitorus ,M.Si
Drs. Eddiyato,Ph.D
: HYDRO & ITS DERITATIVE

STUDY PROGRAM BILINGUAL
CHEMISTRY EDUCATION

FACULTY OF MATHEMATICS AND NATURAL SCIENCES
STATE UNIVERSITY OF MEDAN
MAY 2021

FOREWORD

Praise the presence of God Almighty who has given the author the opportunity to
complete this paper. With His grace and guidance, the author was able to complete a paper
entitled isomer geometri cis-trans and e-z for alkena. This paper was prepared to fulfill the hydro
& its deritative assignment. In addition, the authors also hope that this paper can add insight to
readers about isomer geometric is-trans.

The author would like to thank Mr Dr.Marham SItorus, M.Si as a facilitator in this course.
Hopefully the assignment that has been given can add knowledge and insight related to the field
occupied by the author. The author would also like to thank all those who have helped the
process of preparing this paper.

The author realizes that this writing is far from perfect. Therefore, the authors will accept
constructive criticism and suggestions for the perfection of this paper.

Medan, 18 May, 2021

Group 5

 PRACTICUM TITLE

Cis-trans and e-z geometry isomers for alkena and newaman's projection molecular model is
eclipsed, stagered and anti-zero for n-butane molecules.

 PRACTICUM OBJECTIVES

 Know about geometric isomers
 Know about newaman's projection molecular model is eclipsed, stagered and anti-

zero for n-butane molecules.
 Understand the basic principles of space isomers, especially geometrical isomers

and understand the differences in physical properties between cis and trans
isomeric compounds.
 Understand the Newaman projection molecular model is eclipsed, stagered and
anti for n-butane molecules.

 BASIC THEORY

Geometric isomers are isomers that occur in two molecules that have the same
molecular formula, but differ in the arrangement of the atoms in space. Always remember
that the molecules actually exist in three-dimensional space where the atoms are bonded
in such an arrangement. Geometric isomers occur due to rigidity in molecules and are
only found in two groups of compounds, namely alkenes and cyclic compounds.

If a group or atom is bonded by only sigma bonds (sp3, generally in single-bonded
compounds), then the group or atom that is bound can rotate in such a way that the shape
of the molecule will always be the same.

Example:

Unlike the case with groups or atoms that are bound by double bonds where there are
sigma and pi bonds in the molecule (sp2). This group or atom cannot rotate without first
breaking the pi bond. So that there is a nature of the kinkness of a molecule which causes
if the location of the atom or group is different, then the properties of the compound are
different. This means that the two compounds are different.
Example:

The two compounds above are different where in the first compound the location of the
Cl atom is side-by-side, while in the second compound the location of the Cl atom is
different. The first compound is not easily converted into a second compound, and vice
versa because the double bond between the carbon atoms is rigid.
If in a compound, two of the same groups or atoms are located on one side of the pi bond,
it is called cis, and if they are opposite, it is called trans.

The difference between the two compounds can be proven from differences in their
physical properties such as the boiling points of the two different compounds. The cis-
1,2-dichloroethene compound has a boiling point of 60 degrees Celsius while the trans-
1,2-dichloroethene compound has a boiling point of 48 degrees Celsius.
The requirement for a compound to have a geometric isomer is that each of the accrbon
atoms with a pi (double) bond must bind a different group.

geometric isomers are common in compounds with c = c bonds where each c atom binds
2 different atoms
Example: 2 – pentene

In the pentene compound above, the two carbon atoms that are double bonded bind
different groups of groups. The first carbon atom binds the H atom and the CH3 group,
while the second atom binds the H and the - CH2CH3 group. The pentene compound
above is said to have a geometric isomer.

If the groups or atoms bonded by the double bonded carbon are the same, even though
they have a strong double bond and cannot rotate, the compound is not a geometric
isomer.

Newaman's projection molecular model is eclipsed, stagered and anti-zero for n-
butane molecules.

Conformation is a momentary (temporary) molecular shape as a result of the rotation
of a single bond. The form of this conformation itself is divided into 3, namely Fischer,
Ball Pegs, and also Newman. Each of these forms of conformation itself can conform to
the types of isomeric conformations that are present. In this case there are three types
of isomeric conformations, namely Eclips, Staggered Gausch and Staggered Anti.

The Newman projection is a form of molecular stereoisomerism with the same structural
formula but different conformations due to rotating atoms in chemical bonds. The
different conformers can change from each other by twisting single bonds without
breaking the chemical bond. The Newman projection, useful in alkane stereochemistry,
visualizes the conformation of a chemical bond from front to back, with the front atom
represented by a dot and the back carbon as a circle.

Conformational isomerism (Newman projection) is a form of stereoisomerism of
molecules with the same structural formula but different conformations due to the
rotation of atoms in chemical bonds. The different conformers can change with each
other by rotating the single bond without breaking the chemical bond. The existence of
more than one conformation, usually of different energies, is due to the hindered

rotation of the sp3-orbital hybridization of the carbon atom. Conformational isomerism
only occurs in single bonds because double and triple bonds have pi bonds which
prevent bond rotation.

1. Eclipsed conformation

It is a molecular conformation in which atoms and groups are located side by side,
resulting in electron repulsion which results in this conformation being the most
unstable conformation.

2. Gausch's Staggered Conformation

It is a molecular conformation in which the atoms and groups undergo rotation so that
they are located far apart from each other.

3. Anti Staggered Conformation

It is a molecular conformation where the atoms and groups are located opposite,
resulting in a small repulsion which results in this conformation being the most stable
conformation.

 TOOLS AND MATERIAL

 Name of tool and material experiment 1
1) Toothpick
2) plasticine is red → atom c
3) plasticine is green → atom h

 Name of tool and material experiment 2
1) plasticine is red → atom c as much 4

2) plasticine is green → atom h on the C1 and C4 chains by as much as 6
3) plasticine is blue → atom h on the C3 chains by as much as 2
4) plasticine is yellow → atom h on the C2 chains by as much as 2
5) stick

 WORK PROCEDURES

 experiment 1
- first of all make a double bond from c here I use the example of cis-2 butene and
trans-2- butene then add 2 more c above it because for butene it must have 4 c

after that add 3 h atoms in the c section above then next to it too like that and add
1 atom h for each of the 2-bonded parts of c
Okay this is the result of cis -2 butene
- for the 2 butene trance we just move the ch3 and h atoms to match the material
that when 2 atoms are the same on opposite sides it is called trans
Okay this is the result of trans-2 butene

 experiment 2
- The C2 and C3 carbon chains are joined together because of the newman
projection of the butane seen from the C2- C3 chain

 PRACTICUM RESULT DATA

no THE TREATMENT OBSERVATION PICTURE
BEING OBSERVED
manufacture of cis 2
1 CIS-2-BUTENA butene
done by making a
2 TRANS-2-BUTENA double bond of the c
atom, and the next 2 c
atoms, and making 3 H
atoms on the right and
on the left as well as
below
manufacture of a
butene trance 2
is done by moving the
CH3 atom downward

3 ECLIPS butane is a single
straight chain that has
4 carbon atoms, eclips
is a molecular
conformation in which
atoms and group are
located side by side,
resulting in electron
repulsion which results

STAGGERED in this conformation
GAUSCH becoming the most
unstable conformation,
the c2 dan c3 carbon
chains are joined
together because of the
newman projection of
the butane seen from
the C2-C3 chain
staggered gausch is a
molecular
conformation in which
atoms and group rotate
so that they are located
far apart from each
other

STAGGERED ANTI staggered anti is a
molecular
conformation where
the atoms and groups
are located across so
that it produces a small
repulsion which results
in this conformation
being the most stable
conformation

 CONCLUSION

Geometric isomers are isomers that occur in two molecules that have the same molecular
formula, but differ in the arrangement of the atoms in space. Always remember that the
molecules actually exist in three-dimensional space where the atoms are bonded in such
an arrangement. Geometric isomers occur due to rigidity in molecules and are only found
in two groups of compounds, namely alkenes and cyclic compounds.
Conformation is a momentary (temporary) molecular shape as a result of the rotation of
a single bond. The form of this conformation itself is divided into 3, namely Fischer, Ball

Pegs, and also Newman. Each of these forms of conformation itself can conform to the
types of isomeric conformations that are present. In this case there are three types of
isomeric conformations, namely Eclips, Staggered Gausch and Staggered Anti.

Eclipsed conformation

It is a molecular conformation in which atoms and groups are located side by side,
resulting in electron repulsion which results in this conformation being the most
unstable conformation.

Gausch's Staggered Conformation

It is a molecular conformation in which the atoms and groups undergo rotation so that
they are located far apart from each other.

Anti Staggered Conformation

It is a molecular conformation where the atoms and groups are located opposite,
resulting in a small repulsion which results in this conformation being the most stable
conformation.

 REFERENCE

https://drive.google.com/drive/folders/1C8_iWo2jlEL9SwpSQ_Jja1K1e8J8YOks?usp=sha
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