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Organic Chemistry Chapter 4 – Flashcards

Josephine Mack

7 July 2022

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alkanes and cycloalkanes are hydrocarbons in which all the

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carbon-carbon bonds are single bonds

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hydrocarbons that contain carbon double bonded to carbon is an

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alkene

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hydrocarbons that contain carbon triple bonded to carbon is an

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alkyne

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formula for alkanes is

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CnH2n+2

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formula for cycloalkanes is

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CnH2n

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what type of hybridization and shape do alkanes and cycloalkanes have

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sp3 tetrahedral

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even "straight chain" alkanes are not straight they have a

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zigzag geometry

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examples of straight chain unbranched alkanes are

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butane and pentane

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examples of branched chain alkanes are

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isobutane and neopentane

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butane and isobutane have same molecular formula (C4H10) but have different bond connectivities so they are

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constitutional isomers

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the # of constitutional isomers increases rapidly with

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the number of carbons

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constitutional isomers usually have different

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physical properties

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why do constitutional isomers have diff physcial props

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as we change change we change intermolecular forces which changes properties diff SA=diff intermolec forces

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most commonly used nomenclature system is the

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IUPAC system

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what is the common name for 2-propanol

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isopropanol

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1st rule of naming branched-chain alkanes is

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use longest continuous carbon as parent name

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2nd rule of naming branched-chain alkanes is

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use the lowest number of the sustitiuent

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3rd rule of naming branched-chain alkanes is

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use number obtained by rule 2 to designate location of substituent

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4th rule of naming branched-chain alkanes is

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for 2 or more sub use lowest individual number of parent chain, sub listed in alphabetical order disregarding multiplying prefixes such as di and tri

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5th rule of naming branched-chain alkanes is

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when 2 sub identical on same carbon use that number twice

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6th rule of naming branched-chain alkanes is

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for identical sub use prefixes such as di, tri, tetra, ect

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7th rule of naming branched-chain alkanes is

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2 chains with equal length compete for parents chain choose one with greater number of subs

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8th rule of naming branched-chain alkanes is

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when branching first occurs at equal distance from either end of longest chain, choose name that gives lower number at the first point of difference

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we classify hydrogen atoms by

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what they are connected too

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halogens are treated as

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substituents with prefix such as fluor, chloro, bromo, iodo

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naming alcohols you select longest continuous chain to which the what is directly attached? how do you change name of alkane

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hydroxyl change -e to -ol

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number longest carbon chain that gives carbon bearing the OH the what? indicate what of OH?

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lower number position

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what prefix do you attach to cycloalkanes with only one ring

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cyclo-

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when more then one ring system is attached to a single chain you name it is

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dicyclo

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bicycloalkanes are alkanes containing

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two fused or bridged rings

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when naming alkenes begin numbering at the end of chain closest to

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carbon carbon double bond

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naming alkenes assign location of carbon double bond by

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using number of first atom of carbon double bond as the prefix

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naming alkenes indicate locations of the substitiuent groups by the numbers of the

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carbon atoms to which they are attached

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naming alkenes number substituted cycloalkenes in way that gives carbon atoms of double bond the (2 things)

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1 and 2 position and sub groups lower numbers at first point of difference

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name compounds containing double bond and alcohol group as alkenols and give alcohol carbon the

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lower number

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two identical or sub groups on same side of carbon double bond is

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cis

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two identical or sub groups on opposite sides of carbon double bond i

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trans

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alkynes named in same way as alkenes except

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ending name is changed to -yne

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OH group has priority over

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carbon triple bond

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two groups bonded by a single bond can undergo (with respect to each other)

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rotation about that bond

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temporary molecular shapes that result from a rotation about a single bond

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conformations

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each possible structure of conformation

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conformer

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analysis of energy changes that occur as a molecule undergoes rotations about single bond

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conformational analysis

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cycloalkanes do not have the same relative stability due to

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ring strain

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ring strain comprises

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angular and torsional strain

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result of deviation from idea bond angles caused by inherent structural constraints

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angular strain

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result of dispersion forces that cannot be relieved due to restricted conformational stability

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torsional strain

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cyclobutane ring is not planar but is actually slightly

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folded

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what type of conformation does cyclopentane have

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slightly bent

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what are the two conformers of cyclohexane

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chair and boat form

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what conformation of cyclohexane is less stable and why

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boat higher energy

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what conformation has lower energy than pure boat form conformation and how stable is this conformation compared to the chair form

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twist boat and not as stable as chair form

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what ring is most commonly found in nature

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6 membered ring

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the chair conformation of cyclohexane has two distinct orientations for the bonds that project from the ring which are termed as

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axial and equatorial

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axial hydrogen atoms are either

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up or down in a vertical column

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equatorial hydrogen atoms are

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all angled slightly

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when drawing chair conformational structures try to make corresponding bonds

answer

parallel in your drawing

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for methylcyclohexane the chair conformation with axial G is less stable due to

answer

1,3-diaxial interaction

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the larger the G group the more severe the (2 parts)

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1,3-diaxial interaction and shifted of equilibrium from axial G form chair to equatorial

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the chair conformation with what group is less stable due to 1,3-diaxial interaction

answer

axial tert-butyl group

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upper lower bonds means the groups are

answer

trans

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alkanes, as a class, are characterized by general

answer

inertness to many chemical reagents

question

C-C and C-H bonds are quite (how do they break?)

answer

strong only break when alkanes heated to very high temps

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because C and H atoms have nearly same EN the C-H bonds of alkanes are only

answer

slightly polarized

question

this low reactivity of alkanes toward reagents accounts for the fact that alkanes were originally called what? what does this name mean

answer

paraffins little affinity

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the difference in the number of pairs of hydrogen atoms between the compound under study and an acyclic alkane having the same number of carbons

answer

index of hydrogen deficiency

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each double bond or ring for saturated acyclic alkanes

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has 2 hydrogens less

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each double bond or ring provides

answer

one unit of hydrogen deficiency

question

when calculating IHD for compounds containing halogens count atoms as though they are

answer

hydrogen atoms

question

when calculating IHD for compounds containing oxygen

answer

ignore oxygen atoms and calc IHD from remainder of formula

question

when calculating IHD for compounds containing nitrogen

answer

subtract one hydrogen from each nitrogen atom and ignore nitrogen atoms

question

nature perfers states of

answer

lower PE

question

steric factors (spatial factors) can affect the

answer

stability and reactivity of molecules

question

like charges

answer

repel

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question

alkanes and cycloalkanes are hydrocarbons in which all the

answer

carbon-carbon bonds are single bonds

question

hydrocarbons that contain carbon double bonded to carbon is an

answer

alkene

question

hydrocarbons that contain carbon triple bonded to carbon is an

answer

alkyne

question

formula for alkanes is

answer

CnH2n+2

question

formula for cycloalkanes is

answer

CnH2n

question

what type of hybridization and shape do alkanes and cycloalkanes have

answer

sp3 tetrahedral

question

even "straight chain" alkanes are not straight they have a

answer

zigzag geometry

question

examples of straight chain unbranched alkanes are

answer

butane and pentane

question

examples of branched chain alkanes are

answer

isobutane and neopentane

question

butane and isobutane have same molecular formula (C4H10) but have different bond connectivities so they are

answer

constitutional isomers

question

the # of constitutional isomers increases rapidly with

answer

the number of carbons

question

constitutional isomers usually have different

answer

physical properties

question

why do constitutional isomers have diff physcial props

answer

as we change change we change intermolecular forces which changes properties diff SA=diff intermolec forces

question

most commonly used nomenclature system is the

answer

IUPAC system

question

what is the common name for 2-propanol

answer

isopropanol

question

1st rule of naming branched-chain alkanes is

answer

use longest continuous carbon as parent name

question

2nd rule of naming branched-chain alkanes is

answer

use the lowest number of the sustitiuent

question

3rd rule of naming branched-chain alkanes is

answer

use number obtained by rule 2 to designate location of substituent

question

4th rule of naming branched-chain alkanes is

answer

for 2 or more sub use lowest individual number of parent chain, sub listed in alphabetical order disregarding multiplying prefixes such as di and tri

question

5th rule of naming branched-chain alkanes is

answer

when 2 sub identical on same carbon use that number twice

question

6th rule of naming branched-chain alkanes is

answer

for identical sub use prefixes such as di, tri, tetra, ect

question

7th rule of naming branched-chain alkanes is

answer

2 chains with equal length compete for parents chain choose one with greater number of subs

question

8th rule of naming branched-chain alkanes is

answer

when branching first occurs at equal distance from either end of longest chain, choose name that gives lower number at the first point of difference

question

we classify hydrogen atoms by

answer

what they are connected too

question

halogens are treated as

answer

substituents with prefix such as fluor, chloro, bromo, iodo

question

naming alcohols you select longest continuous chain to which the what is directly attached? how do you change name of alkane

answer

hydroxyl change -e to -ol

question

number longest carbon chain that gives carbon bearing the OH the what? indicate what of OH?

answer

lower number position

question

what prefix do you attach to cycloalkanes with only one ring

answer

cyclo-

question

when more then one ring system is attached to a single chain you name it is

answer

dicyclo

question

bicycloalkanes are alkanes containing

answer

two fused or bridged rings

question

when naming alkenes begin numbering at the end of chain closest to

answer

carbon carbon double bond

question

naming alkenes assign location of carbon double bond by

answer

using number of first atom of carbon double bond as the prefix

question

naming alkenes indicate locations of the substitiuent groups by the numbers of the

answer

carbon atoms to which they are attached

question

naming alkenes number substituted cycloalkenes in way that gives carbon atoms of double bond the (2 things)

answer

1 and 2 position and sub groups lower numbers at first point of difference

question

name compounds containing double bond and alcohol group as alkenols and give alcohol carbon the

answer

lower number

question

two identical or sub groups on same side of carbon double bond is

answer

cis

question

two identical or sub groups on opposite sides of carbon double bond i

answer

trans

question

alkynes named in same way as alkenes except

answer

ending name is changed to -yne

question

OH group has priority over

answer

carbon triple bond

question

two groups bonded by a single bond can undergo (with respect to each other)

answer

rotation about that bond

question

temporary molecular shapes that result from a rotation about a single bond

answer

conformations

question

each possible structure of conformation

answer

conformer

question

analysis of energy changes that occur as a molecule undergoes rotations about single bond

answer

conformational analysis

question

cycloalkanes do not have the same relative stability due to

answer

ring strain

question

ring strain comprises

answer

angular and torsional strain

question

result of deviation from idea bond angles caused by inherent structural constraints

answer

angular strain

question

result of dispersion forces that cannot be relieved due to restricted conformational stability

answer

torsional strain

question

cyclobutane ring is not planar but is actually slightly

answer

folded

question

what type of conformation does cyclopentane have

answer

slightly bent

question

what are the two conformers of cyclohexane

answer

chair and boat form

question

what conformation of cyclohexane is less stable and why

answer

boat higher energy

question

what conformation has lower energy than pure boat form conformation and how stable is this conformation compared to the chair form

answer

twist boat and not as stable as chair form

question

what ring is most commonly found in nature

answer

6 membered ring

question

the chair conformation of cyclohexane has two distinct orientations for the bonds that project from the ring which are termed as

answer

axial and equatorial

question

axial hydrogen atoms are either

answer

up or down in a vertical column

question

equatorial hydrogen atoms are

answer

all angled slightly

question

when drawing chair conformational structures try to make corresponding bonds

answer

parallel in your drawing

question

for methylcyclohexane the chair conformation with axial G is less stable due to

answer

1,3-diaxial interaction

question

the larger the G group the more severe the (2 parts)

answer

1,3-diaxial interaction and shifted of equilibrium from axial G form chair to equatorial

question

the chair conformation with what group is less stable due to 1,3-diaxial interaction

answer

axial tert-butyl group

question

upper lower bonds means the groups are

answer

trans

question

alkanes, as a class, are characterized by general

answer

inertness to many chemical reagents

question

C-C and C-H bonds are quite (how do they break?)

answer

strong only break when alkanes heated to very high temps

question

because C and H atoms have nearly same EN the C-H bonds of alkanes are only

answer

slightly polarized

question

this low reactivity of alkanes toward reagents accounts for the fact that alkanes were originally called what? what does this name mean

answer

paraffins little affinity

question

the difference in the number of pairs of hydrogen atoms between the compound under study and an acyclic alkane having the same number of carbons

answer

index of hydrogen deficiency

question

each double bond or ring for saturated acyclic alkanes

answer

has 2 hydrogens less

question

each double bond or ring provides

answer

one unit of hydrogen deficiency

question

when calculating IHD for compounds containing halogens count atoms as though they are

answer

hydrogen atoms

question

when calculating IHD for compounds containing oxygen

answer

ignore oxygen atoms and calc IHD from remainder of formula

question

when calculating IHD for compounds containing nitrogen

answer

subtract one hydrogen from each nitrogen atom and ignore nitrogen atoms

question

nature perfers states of

answer

lower PE

question

steric factors (spatial factors) can affect the

answer

stability and reactivity of molecules

question

like charges

answer

repel

Organic Chemistry Chapter 4 – Flashcards

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