Organic chemistry
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Questions and Answers

What type of atoms are present in the fused ring structure of heterocyclic polynuclear compounds?

  • Only carbon atoms
  • Hetero-atoms like nitrogen, oxygen, or sulfur (correct)
  • Only oxygen atoms
  • Only hydrogen atoms

    • What is the study of stereoisomers known as?

  • Organic Chemistry
  • Heterocyclic Chemistry
  • Stereochemistry (correct)
  • Chirality Study

    • What is a chirality center?

  • A carbon atom bonded to three different atoms
  • A carbon atom bonded to two different atoms
  • A carbon atom bonded to five different atoms
  • A carbon atom bonded to four different atoms or groups (correct)

    • What is the term for isomers that contain chirality centers?

    <p>Optical isomers</p> Signup and view all the answers

    What do stereoisomers differ in?

    <p>Spatial arrangement</p> Signup and view all the answers

    What is the term for the study of the spatial arrangement of atoms in molecules?

    <p>Stereochemistry</p> Signup and view all the answers

    What is enantiomeric excess used to quantify?

    <p>The difference between two enantiomers in a mixture</p> Signup and view all the answers

    What is the formula to calculate enantiomeric excess?

    <p>((60-50)×100)/50</p> Signup and view all the answers

    What is the correct configuration of the molecule with two CH3 groups on the same side of the double bond?

    <p>(E)-</p> Signup and view all the answers

    What is the term used to describe the geometric isomers of an alkene with one substituent on each carbon?

    <p>Cis-trans system</p> Signup and view all the answers

    Why can't you directly translate cis- and trans- into (Z)- and (E)-?

    <p>Because the two systems have different priorities</p> Signup and view all the answers

    What is the optical rotation of a sample of a mixture of R and S carvone that has an enantiomeric excess of 20%?

    <p>(-)23°</p> Signup and view all the answers

    What is the purpose of both the cis-trans and (Z)-(E) systems?

    <p>To enable you to decode a name and write a correct formula</p> Signup and view all the answers

    What is the specific rotation of (S)-(+)-2-bromobutane?

    <p>+23.1°</p> Signup and view all the answers

    What is the type of isomerism exhibited by 1-ethyl-3-methylcyclobutane?

    <p>Geometric isomerism</p> Signup and view all the answers

    What should you do when converting between the cis-trans and (Z)-(E) systems?

    <p>Start from scratch in each case</p> Signup and view all the answers

    Why is the cis-trans system only suitable for very straightforward molecules?

    <p>Because it is less accurate</p> Signup and view all the answers

    What happens when you assume that you can directly convert between the cis-trans and (Z)-(E) systems?

    <p>You get different results</p> Signup and view all the answers

    What does a levorotatory compound do to the plane of polarization?

    <p>Rotates it in a counter-clockwise direction</p> Signup and view all the answers

    What do the prefixes 'dextro' and 'levo' mean in Latin?

    <p>To the right and to the left</p> Signup and view all the answers

    What is the function of a polarimeter?

    <p>To measure the amount of rotation of plane-polarized light by a compound</p> Signup and view all the answers

    What is the unit of measurement for specific rotation?

    <p>Degrees per decimeter</p> Signup and view all the answers

    What is the symbol used to indicate specific rotation?

    <p>[α]</p> Signup and view all the answers

    At what temperature is specific rotation normally measured?

    <p>20°C</p> Signup and view all the answers

    What is a characteristic of aromatic compounds?

    <p>They contain a benzene ring structure and exhibit unique stability</p> Signup and view all the answers

    What is the definition of heterocyclic compounds?

    <p>Compounds with rings made of carbon atoms including one or more different atoms</p> Signup and view all the answers

    What is the name of the compounds containing more than one benzene ring?

    <p>Polynuclear compounds</p> Signup and view all the answers

    Why is carbon able to form a large number of compounds?

    <p>Due to its ability to unite with another carbon by a double or multiple bond</p> Signup and view all the answers

    What is the number of organic compounds that exceed a certain number?

    <p>1,000,000</p> Signup and view all the answers

    What is one of the unique properties of carbon?

    <p>Tetravalency of Carbon</p> Signup and view all the answers

    ----- is when organic compounds are synthesized from living things using vital force.

    <p>Vitalism</p> Signup and view all the answers

    What year and who created urea

    <p>Fredrick wholer 1928</p> Signup and view all the answers

    What is a branch of study that deals with the study of carbons,nitrogen,hydrogen,and halogen compounds except cynate,Ho cynate and silicon

    <p>Organic chemistry</p> Signup and view all the answers

    What is the ability for carbon to form a bond a bond with other elements or itself

    <p>Catenation</p> Signup and view all the answers

    Carbon= 1s²,2s²,2p². 1s² can take part in the reaction because it is very close to tge nucleus

    <p>False</p> Signup and view all the answers

    Process whereby electron is transferred from the lowest level to the highest level

    <p>Promotion reaction</p> Signup and view all the answers

    Process whereby two or more atomic orbital reacts to form a newly hybridized one

    <p>Hybridization</p> Signup and view all the answers

    Most important organic bond is called?

    <p>Covalent bond</p> Signup and view all the answers

    Types of covalent bonds

    <p>Sigma and pie bond</p> Signup and view all the answers

    What is a very strong bond and cannot be easily broken and doesnt take part in organjc reactions

    <p>Sigma bonds</p> Signup and view all the answers

    What type of bond is a very weak bond and can easily be broken,also takes part in organic reactions

    <p>Pie bonds</p> Signup and view all the answers

    The process whereby s orbital reacts to p orbital to create neither S nor P orbital is called?

    <p>Hybridization</p> Signup and view all the answers

    Types of hybridization

    <p>Formation of sigma bond; sp-sp,sp-s,sp-p,p-p,s-s,s-p. Formatuon of pie bond; p-p</p> Signup and view all the answers

    Sp³,Sp²,Sp are types of hybridization

    <p>True</p> Signup and view all the answers

    Type of hybridization that occurs when s- orbital reacts with 3p's(px,py&pz) leaving none hybridized.

    <p>Sp³</p> Signup and view all the answers

    What hybridization only occurs in single bond,alkane,has 109.5° or 109.28° and is tetrahedral in shape

    <p>Sp3</p> Signup and view all the answers

    S+ px+py+pz=

    <p>3sp3</p> Signup and view all the answers

    What type of hybridization occurs when s- orbitals reacts with 2ps(px&py) leaving one p (pz)unhybridized.

    <p>Sp2</p> Signup and view all the answers

    Type of hybridization that Occurs in double compounda e.g alkene,trigonal in shape with an angle of 180°

    <p>Sp2</p> Signup and view all the answers

    Hybridization that occurs when s-orbital reacts with one p(px) leaving two p's unhybridized (py&pz).

    <p>Sp</p> Signup and view all the answers

    Type of hybridization that occurs in triple bonds,alkyne,linear in shape with an angle of 180°

    <p>Sp</p> Signup and view all the answers

    S+px+py=

    <p>3sp²</p> Signup and view all the answers

    S+px=

    <p>2sp</p> Signup and view all the answers

    State the terms used in hybridization

    <p>Electronegativity,Bond length,Bond strength,Reactivity,Bond order,percentage of s- character,percentage of p-character.</p> Signup and view all the answers

    The distance between two atoms in an organic compound or reaction is called?

    <p>Bond length</p> Signup and view all the answers

    The higher the distance the higher rhe bond strength

    <p>True</p> Signup and view all the answers

    The process whereby an element accepts or attracts electron towards itself in order to become negatively charged is called?

    <p>Electronegativity</p> Signup and view all the answers

    The lower the pie electron the higher the electronegativity

    <p>False</p> Signup and view all the answers

    Sp>Sp²>Sp3 does electronegativity decreases or increases?

    <p>Decreases</p> Signup and view all the answers

    The amount of energy required to break the bond in an organic compound is called?

    <p>Bond strength</p> Signup and view all the answers

    The shorter the distance,the stronger the bond and vice versa

    <p>True</p> Signup and view all the answers

    Sp>Sp²>Sp³ bond strength increases or decreases?

    <p>Decreases</p> Signup and view all the answers

    The higher the pie bond,the higher the reactivity

    <p>True</p> Signup and view all the answers

    Percentage of s character

    <p>No of s ÷no of sp produced ×100</p> Signup and view all the answers

    Percentage of p- character

    <p>No of p ÷ no of sp produced×100</p> Signup and view all the answers

    ----------is the existence of two or more compounds having the same molecular formular but different strutural formula

    <p>Isomerism</p> Signup and view all the answers

    Typse of isomerism

    <p>Constitutional and stereoisomers</p> Signup and view all the answers

    Constitutional isomerisim is also known as?

    <p>Structural</p> Signup and view all the answers

    Isomers tgat differs in the way that their atoms are attached/connected,i.e joined together is called?

    <p>Constitutional isomers</p> Signup and view all the answers

    Isomers thqt their atoms are arranged in space are called?

    <p>Stereoisomers</p> Signup and view all the answers

    The study of of three dimensional structure of molecules is called?

    <p>Stereochemistry</p> Signup and view all the answers

    Types of stereoisomers

    <p>Conformational and configurational</p> Signup and view all the answers

    Type of streoisomers that results in the rotation of c-c single bond is called?

    <p>Constitutional isomers</p> Signup and view all the answers

    Amine inversion/umberalla effect is ?

    <p>Constitutional isomers</p> Signup and view all the answers

    Conformers that interconvert rapidly at room temp thus cant be seperated is called?

    <p>Conformational isomers</p> Signup and view all the answers

    Type of stereo isomers that do not interconver and can be easily seperated is called?

    <p>Configurational</p> Signup and view all the answers

    Tyeos of configurational Isomers

    <p>Geometrical and Enantiomers</p> Signup and view all the answers

    Enantiomers are also known as?

    <p>Optical isomers</p> Signup and view all the answers

    Enantiomers contaim chirality centers

    <p>True</p> Signup and view all the answers

    Types of structural isomers

    <p>Chain,position,Ring,Tauto,meta</p> Signup and view all the answers

    Optical isomers are also known as?

    <p>Chirality centers</p> Signup and view all the answers

    an atom that has four different groups bonded to it in such a manner that it has a nonsuperimposable mirror image is called

    <p>Chiralíty center</p> Signup and view all the answers

    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

    <p>True</p> Signup and view all the answers

    Isomers that are nonidentical (nonsuperimposable) mirror image are called?

    <p>enantiomers</p> Signup and view all the answers

    (Enantiomers is from the Greek word called and it means what?

    <p>Enantion,means opposite</p> Signup and view all the answers

    A molecule that has a nonidentical mirror image is said to be?

    <p>chiral</p> Signup and view all the answers

    A chiral molecule does not contain a plane of symmetry.

    <p>True</p> Signup and view all the answers

    Aplane that cuts a molecule into two halves, each of which is a mirror image of the other.

    <p>plane of symmetry</p> Signup and view all the answers

    Chiral objects do not contain a plane of symmetry

    <p>hands, – feet, – shoes,</p> Signup and view all the answers

    molecule containing a plane of symmetry is?

    <p>achiral</p> Signup and view all the answers

    A chirality centre is what cause a molecule to be chiral.

    <p>True</p> Signup and view all the answers

    There are two ways by which enantiomers can be drawn

    <p>The perspective formula; and –The Fischer projections formula.</p> Signup and view all the answers

    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?

    <p>Perspective formulq</p> Signup and view all the answers

    Fischer projection formula was devised by in what year?

    <p>Emil fischer,1800</p> Signup and view all the answers

    – 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

    <p>Fishers projection formula</p> Signup and view all the answers

    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?

    <p>All of the above</p> Signup and view all the answers

    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.

    <p>True</p> Signup and view all the answers

    The priority depends on the atomic number of the atoms directly attached to the chirality centre.

    <p>True</p> Signup and view all the answers

    The greater the atomic number the higher the priority

    <p>True</p> Signup and view all the answers

    In Naming Enantiomers: R ands S system of Nomenclature. What does r and s mean in latin and english

    <p>R= rectus which means right while s=sinister means left turn</p> Signup and view all the answers

    A chirality center is also refer to as

    <p>stereogenic centre, – streocentre, – asymmetric carbon</p> Signup and view all the answers

    Enantiomers can be named as?

    <p>R or S</p> Signup and view all the answers

    the R and S system of nomenclature of stereoisomers now known as?

    <p>Cahn – Ingold - prelog(CIP)</p> Signup and view all the answers

    -----is a phenomenon observed when a molecule rotates the plane of polarization.

    <p>Optical rotation</p> Signup and view all the answers

    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

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    Description

    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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