104 Questions
What type of atoms are present in the fused ring structure of heterocyclic polynuclear compounds?
Hetero-atoms like nitrogen, oxygen, or sulfur
What is the study of stereoisomers known as?
Stereochemistry
What is a chirality center?
A carbon atom bonded to four different atoms or groups
What is the term for isomers that contain chirality centers?
Optical isomers
What do stereoisomers differ in?
Spatial arrangement
What is the term for the study of the spatial arrangement of atoms in molecules?
Stereochemistry
What is enantiomeric excess used to quantify?
The difference between two enantiomers in a mixture
What is the formula to calculate enantiomeric excess?
((60-50)×100)/50
What is the correct configuration of the molecule with two CH3 groups on the same side of the double bond?
(E)-
What is the term used to describe the geometric isomers of an alkene with one substituent on each carbon?
Cis-trans system
Why can't you directly translate cis- and trans- into (Z)- and (E)-?
Because the two systems have different priorities
What is the optical rotation of a sample of a mixture of R and S carvone that has an enantiomeric excess of 20%?
(-)23°
What is the purpose of both the cis-trans and (Z)-(E) systems?
To enable you to decode a name and write a correct formula
What is the specific rotation of (S)-(+)-2-bromobutane?
+23.1°
What is the type of isomerism exhibited by 1-ethyl-3-methylcyclobutane?
Geometric isomerism
What should you do when converting between the cis-trans and (Z)-(E) systems?
Start from scratch in each case
Why is the cis-trans system only suitable for very straightforward molecules?
Because it is less accurate
What happens when you assume that you can directly convert between the cis-trans and (Z)-(E) systems?
You get different results
What does a levorotatory compound do to the plane of polarization?
Rotates it in a counter-clockwise direction
What do the prefixes 'dextro' and 'levo' mean in Latin?
To the right and to the left
What is the function of a polarimeter?
To measure the amount of rotation of plane-polarized light by a compound
What is the unit of measurement for specific rotation?
Degrees per decimeter
What is the symbol used to indicate specific rotation?
[α]
At what temperature is specific rotation normally measured?
20°C
What is a characteristic of aromatic compounds?
They contain a benzene ring structure and exhibit unique stability
What is the definition of heterocyclic compounds?
Compounds with rings made of carbon atoms including one or more different atoms
What is the name of the compounds containing more than one benzene ring?
Polynuclear compounds
Why is carbon able to form a large number of compounds?
Due to its ability to unite with another carbon by a double or multiple bond
What is the number of organic compounds that exceed a certain number?
1,000,000
What is one of the unique properties of carbon?
Tetravalency of Carbon
----- is when organic compounds are synthesized from living things using vital force.
Vitalism
What year and who created urea
Fredrick wholer 1928
What is a branch of study that deals with the study of carbons,nitrogen,hydrogen,and halogen compounds except cynate,Ho cynate and silicon
Organic chemistry
What is the ability for carbon to form a bond a bond with other elements or itself
Catenation
Carbon= 1s²,2s²,2p². 1s² can take part in the reaction because it is very close to tge nucleus
False
Process whereby electron is transferred from the lowest level to the highest level
Promotion reaction
Process whereby two or more atomic orbital reacts to form a newly hybridized one
Hybridization
Most important organic bond is called?
Covalent bond
Types of covalent bonds
Sigma and pie bond
What is a very strong bond and cannot be easily broken and doesnt take part in organjc reactions
Sigma bonds
What type of bond is a very weak bond and can easily be broken,also takes part in organic reactions
Pie bonds
The process whereby s orbital reacts to p orbital to create neither S nor P orbital is called?
Hybridization
Types of hybridization
Formation of sigma bond; sp-sp,sp-s,sp-p,p-p,s-s,s-p. Formatuon of pie bond; p-p
Sp³,Sp²,Sp are types of hybridization
True
Type of hybridization that occurs when s- orbital reacts with 3p's(px,py&pz) leaving none hybridized.
Sp³
What hybridization only occurs in single bond,alkane,has 109.5° or 109.28° and is tetrahedral in shape
Sp3
S+ px+py+pz=
3sp3
What type of hybridization occurs when s- orbitals reacts with 2ps(px&py) leaving one p (pz)unhybridized.
Sp2
Type of hybridization that Occurs in double compounda e.g alkene,trigonal in shape with an angle of 180°
Sp2
Hybridization that occurs when s-orbital reacts with one p(px) leaving two p's unhybridized (py&pz).
Sp
Type of hybridization that occurs in triple bonds,alkyne,linear in shape with an angle of 180°
Sp
S+px+py=
3sp²
S+px=
2sp
State the terms used in hybridization
Electronegativity,Bond length,Bond strength,Reactivity,Bond order,percentage of s- character,percentage of p-character.
The distance between two atoms in an organic compound or reaction is called?
Bond length
The higher the distance the higher rhe bond strength
True
The process whereby an element accepts or attracts electron towards itself in order to become negatively charged is called?
Electronegativity
The lower the pie electron the higher the electronegativity
False
Sp>Sp²>Sp3 does electronegativity decreases or increases?
Decreases
The amount of energy required to break the bond in an organic compound is called?
Bond strength
The shorter the distance,the stronger the bond and vice versa
True
Sp>Sp²>Sp³ bond strength increases or decreases?
Decreases
The higher the pie bond,the higher the reactivity
True
Percentage of s character
No of s ÷no of sp produced ×100
Percentage of p- character
No of p ÷ no of sp produced×100
----------is the existence of two or more compounds having the same molecular formular but different strutural formula
Isomerism
Typse of isomerism
Constitutional and stereoisomers
Constitutional isomerisim is also known as?
Structural
Isomers tgat differs in the way that their atoms are attached/connected,i.e joined together is called?
Constitutional isomers
Isomers thqt their atoms are arranged in space are called?
Stereoisomers
The study of of three dimensional structure of molecules is called?
Stereochemistry
Types of stereoisomers
Conformational and configurational
Type of streoisomers that results in the rotation of c-c single bond is called?
Constitutional isomers
Amine inversion/umberalla effect is ?
Constitutional isomers
Conformers that interconvert rapidly at room temp thus cant be seperated is called?
Conformational isomers
Type of stereo isomers that do not interconver and can be easily seperated is called?
Configurational
Tyeos of configurational Isomers
Geometrical and Enantiomers
Enantiomers are also known as?
Optical isomers
Enantiomers contaim chirality centers
True
Types of structural isomers
Chain,position,Ring,Tauto,meta
Optical isomers are also known as?
Chirality centers
an atom that has four different groups bonded to it in such a manner that it has a nonsuperimposable mirror image is called
Chiralíty center
A compound containing a chirality centre can exist as two different isomers. The two isomers cannot be super imposed. Just as you cannot super impose your left hand on your right hand
True
Isomers that are nonidentical (nonsuperimposable) mirror image are called?
enantiomers
(Enantiomers is from the Greek word called and it means what?
Enantion,means opposite
A molecule that has a nonidentical mirror image is said to be?
chiral
A chiral molecule does not contain a plane of symmetry.
True
Aplane that cuts a molecule into two halves, each of which is a mirror image of the other.
plane of symmetry
Chiral objects do not contain a plane of symmetry
hands, – feet, – shoes,
molecule containing a plane of symmetry is?
achiral
A chirality centre is what cause a molecule to be chiral.
True
There are two ways by which enantiomers can be drawn
The perspective formula; and –The Fischer projections formula.
two lines are used to used to represent two of the bonds to the chirality center in the plane of the paper, – one bond as a solid wedge coming out of the paper; and – the fourth bond as a hatched wedge projecting back from the paper. What way of drawing enatiomers is this?
Perspective formulq
Fischer projection formula was devised by in what year?
Emil fischer,1800
– The point of intersection of two perpendicular lines are used to represent the chirality centre, – horizontal lines represent the bonds that project out of the plane of the paper toward the viewer; and – vertical line represent the bonds that project back form the plane of the paper away from the viewer. – The carbon chain is drawn vertically with C- 1 at the top
Fishers projection formula
To distinguish between two enantiomers, a system of nomenclature that indicates the configuration (arrangement) of the groups (or atoms) about the chirality center was devised by three chemist named?
All of the above
The first step in the naming system; is to rank the groups (or atoms) that are bonded to the chirality center in order of priority.
True
The priority depends on the atomic number of the atoms directly attached to the chirality centre.
True
The greater the atomic number the higher the priority
True
In Naming Enantiomers: R ands S system of Nomenclature. What does r and s mean in latin and english
R= rectus which means right while s=sinister means left turn
A chirality center is also refer to as
stereogenic centre, – streocentre, – asymmetric carbon
Enantiomers can be named as?
R or S
the R and S system of nomenclature of stereoisomers now known as?
Cahn – Ingold - prelog(CIP)
-----is a phenomenon observed when a molecule rotates the plane of polarization.
Optical rotation
Study Notes
Enantiomeric Excess (ee)
- Enantiomeric excess (ee) is used to quantify the difference when a mixture contains more of one enantiomer than the other.
- ee is expressed as ((percentage of R enantiomer - 50) × 100) / 50.
Exercises
- A mixture containing 60% R enantiomer and 40% S enantiomer has a 20% enantiomeric excess of R.
- In a sample of carvone, if the optical rotation is (-)23° and the specific rotation of (S)-carvone is (+)61°, the enantiomer in excess is S, and its ee is 63.3%.
- The percentage of (R)-carvone is 18.5%, and (S)-carvone is 81.5%.
- If the specific rotation of (S)-(+)2-bromobutane is +23.1° and a sample has an observed specific rotation of +9.2°, its optical purity is 40%.
- A mixture of 3g of (+)-2-bromobutane and 2g of (–)-2-bromobutane has a rotation of +12.21°.
Geometric Isomers
- In an alkene, if hydrogens are on the same side of the double bond, it is the cis isomer; if they are on opposite sides, it is the trans isomer.
- The cis-trans system can be unreliable and may not always work; it is safer to start from scratch in each case.
Heterocyclic Compounds
- Heterocyclic compounds contain heteroatoms like nitrogen, oxygen, or sulfur within the fused ring structure.
- They can have unique properties and reactivities.
Stereochemistry
- Stereochemistry is the study of stereoisomers, which are isomers with atoms connected in the same way but differing in spatial arrangement.
- Optical isomers contain chirality centers, where a carbon atom is bonded to four different atoms or groups of atoms.
- A carbon atom bonded to four different atoms or groups of atoms is known as a chirality center or stereogenic center.
Polarimeter and Specific Rotation
- A polarimeter is an instrument that measures the amount an optically active compound rotates plane-polarized light.
- Specific rotation is the number of degrees of rotation caused by a solution of 1.0 g of the compound per mL of solution in a sample tube 1.0 dm long at a specified temperature and wavelength.
Heterocyclic and Aromatic Compounds
- Heterocyclic compounds have rings made of carbon atoms and one or more heteroatoms like oxygen, nitrogen, sulfur, and phosphorus.
- Aromatic compounds contain a benzene ring structure and exhibit unique stability due to resonance.
- Polynuclear compounds, also known as polycyclic aromatic hydrocarbons, are organic compounds composed of two or more benzene rings that are fused together.
Unique Properties of Carbon
- Carbon forms a large number of compounds due to its unique properties:
- Tetravalency of carbon
- Ability to form double or multiple bonds with another carbon
- Strong covalent bonds with other elements like nitrogen, oxygen, sulfur, halogens, and phosphorus
This quiz covers the properties and reactivities of heterocyclic polynuclear compounds, which contain hetero-atoms like nitrogen, oxygen, or sulfur within the fused ring structure. Learn about the unique characteristics of these compounds and how they behave. Test your knowledge and understanding of these complex molecules.
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