4.1 Basic concepts of organic chemistry Flashcards
1
Q
what are the steps for naming organic compounds?
A
1 - find the longest continuous carbon chain
2 - look for functional group
3 - number the functional group and use the lowest number
4 - add the side chain - if there is 2 side chains put in alphabetic order
2
Q
what is the prefix of an organic compound with 1 carbon?
A
meth
3
Q
what is the prefix of an organic compound with 2 carbons?
A
eth
4
Q
what is the prefix of an organic compound with 3 carbons?
A
prop
5
Q
what is the prefix of an organic compound with 4 carbons?
A
but
6
Q
what is the prefix of an organic compound with 5 carbons?
A
pent
7
Q
what is the prefix of an organic compound with 6 carbons?
A
hex
8
Q
what is the prefix of an organic compound with 7 carbons?
A
hept
9
Q
what is the prefix of an organic compound with 8 carbons?
A
oct
10
Q
what is the prefix of an organic compound with 9 carbons?
A
non
11
Q
what is the prefix of an organic compound with 10 carbons?
A
dec
12
Q
what is the ending of an organic compound that is an alkane?
A
- ane
13
Q
what is the ending of an organic compound that is an haloalkane?
A
- ane
14
Q
what is the ending of an organic compound that is an alcohol?
A
- ol
15
Q
what is the ending of an organic compound that is an alkene?
A
- ene
16
Q
what is the ending of an organic compound that is an aldehyde?
A
- al
17
Q
what is the ending of an organic compound that is a ketone?
A
- one
18
Q
what is the ending of an organic compound that is a carboxylic acid?
A
- oic acid
19
Q
what is the functional group of an alkane?
A
there is none
20
Q
what is the functional group of an haloalkane?
A
a halogen - group 7
21
Q
what is the functional group of an alcohol?
A
OH
22
Q
what is the functional group of an alkene?
A
C = C (carbon double bond)
23
Q
what is the functional group of an aldehyde?
A
O = C– H (oxygen double bond to carbon then carbon to hydrogen single bond)
24
Q
what is the functional group of a ketone?
A
O = C – C (oxygen double bond to carbon then carbon to carbon single bond)
25
what is the functional group of a carboxylic acid?
O = C -- OH (oxygen double bond to carbon then carbon to hydroxide single bond)
26
if there is 1 carbon on the side chain off the longest carbon chain, what does the compound name start with?
methyl
27
if there is 1 carbon on the side chain off the longest carbon chain, what does the compound name start with?
ethyl
28
if there is 3 carbons on the side chain off the longest carbon chain, what does the compound name start with?
propyl
29
what does homologous series mean?
same functional group but change by CH2
30
what is a functional group?
responsible for the characteristic of a compound
31
what is the general formula of an alkyl group?
CnH2n +1
32
what does aliphatic mean?
a compound containing hydrogen and carbon joined together in straight, branched or non aromatic rings
33
what is an example of something that is not aliphatic?
benzene ring
34
what does alicyclic mean?
aliphatic compounds arranged in non aromatic rings with or without side chains e.g. cyclohexane
35
what does aromatic mean?
compound containing a benzene ring
36
what is a saturated hydrocarbon?
contains only single bonds
37
what is an unsaturated hydrocarbon?
contains double / triple bonds
38
are alkanes reactive or unreactive?
unreactive
39
what bonds do alkanes contain?
sigma bonds
40
where does a sigma bond form in an alkane?
each covalent bond has a direct overlap of the electron clouds from each atom making a sigma bond
41
what shape are all alkanes?
tetrahedral
42
what does more branching on an alkane mean for the melting and boiling point?
lower melting and boiling point
43
why does more branching on an alkane mean lower melting and boiling points?
- there are less points of contact
- weaker London forces
- less energy needed to overcome
- boiling point decreases
44
why are alkanes unreactive?
carbon to carbon and carbon to hydrogen bonds are strong covalent
carbon to carbon bonds are non polar
carbon to hydrogen bonds are virtually non polar
molecules are symmetrical therefore non polar
45
what does the name of a compound start with if there is more than one of the same group found on the carbon chain?
di if 2
tri if 3
46
what is the definition for displayed formula?
shows the relative positions of all the atoms in a molecule and the bonds between them
47
what is the definition of structural formula?
gives the minimum detail for the arrangement of atoms in a molecule e.g. (CH3)2CO
48
what is the definition of skeletal formula?
the briefest way of representing organic compounds or molecules
lines are used to indicate alkyl chains and every corner represents a carbon
49
what is the definition of an isomer?
a compound that had the same molecular formula but different structural formula
50
what is chain structural isomerism caused by?
caused by different arrangements of the carbon skeleton
51
do chain structural isomers have similar chemical properties to each other?
Yes
52
do chain structural isomers have similar physical properties to each other?
No - they are slightly different
53
what does more branching in a chain structural isomer mean?
lower boiling point
54
what is important about the functional group in a structural isomer?
it has the same functional group just in a different position
molecule has the same carbon skeleton
55
what is a functional group structural isomer?
molecules have the same molecular formula
molecules have different functional group
56
do functional group structural isomers have the same chemical properties?
no - they have different
57
do functional group structural isomers gave the same physical properties?
no - they have different
58
why are alkanes commonly used as fuels?
they react well with a supply of oxygen, releasing energy
59
what is complete combustion?
plentiful supply of oxygen, combustion will always lead to the production of carbon dioxide and water
60
what is the word equation for complete combustion?
fuel + oxygen —-> carbon dioxide + water
61
what is incomplete combustion?
in a limited supply of oxygen, combustion of alkanes will lead to the production of carbon monoxide, soot and water
62
what is an example of a word equation for incomplete combustion?
butane + oxygen —-> carbon + carbon monoxide + water
63
what conditions are needed for free radical substitution to take place?
UV light - causes the covalent bond in a diatomic molecule to break, allowing a reaction with an alkane
64
what is the first step in free radical substitution?
initiation (homolytic fission)
the breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals
65
give an example of an initiation equation in free radical substitution
UV
Cl2 —-> 2 ~ Cl
66
what is a radical?
a highly reactive species due to having an unpaired electron
67
what is step two in free radical substitution?
propagation (ALWAYS TWO STEPS)
the free radical reacts with a molecule to produce a new molecule and new free radical
1. CH4 + Cl . —-> . CH3 +HCL
2. .CH3 + Cl2 —-> CH3Cl + Cl.
68
what is step three in free radical substitution?
termination - TWO free radicals react to form a new molecule
.CH3 + .CH3 —> CH3CH3
Cl . + Cl . —-> Cl2
Cl . + . CH3 —-> CH3Cl
69
why is further substitution to alkanes not the most efficient process?
lots of products made so not a good/efficient way of making a particular product
the reaction has a limited use in synthesis (making desired product in a number of steps)
70
how many bonding regions do alkenes have?
three
71
how many lone pairs do alkenes have?
none
72
what is the general formula for an alkene?
C2H2n
73
what are the bond angle in alkenes?
120 degrees
74
what are the shape of alkenes?
trigonal planar
75
are alkenes homologous series?
yes
76
are alkenes hydrocarbons?
yes
77
are alkenes saturated or unsaturated?
unsaturated
78
what double bond do alkenes have?
carbon to carbon
79
how are double bonds created in alkenes?
1 - covalent bonds are formed by overlapping orbitals
2 - an sp2 orbital from each carbon overlaps to form a single carbon to carbon bond
3 - the resulting bond is a sigma bond
4 - orbitals above and below the plane overlap to form a pi bond
80
what bond is in single carbon to carbon bond in an alkene?
sigma
81
what bond is above and below the plane in an alkene?
pi bond
82
what is a stereoisomer?
a compound with the same structural formula but with a different arrangement in space
83
why does structural isomerism occur?
due to the restricted rotation of carbon to carbon double bonds
84
when is something a Z stereo isomer?
when the highest priority groups are on the same side of the double bond
85
when is something an E stereo isomer?
when the highest priority groups are on the opposite sides across the double bond
86
when are there no stereo isomers?
if a C in the double bond has the same group on
87
when can cis-trans stereoisomerism occur?
if both carbons on the double bond contain the same group
88
when does cis stereoisomerism occur?
when it doesn't go across the double bond
89
when does trans stereoisomerism occur?
when it goes across the double bond (down in a diagonal)
90
what is the bond enthalpy on a carbon to carbon single bond?
+347 kJ mol-1
91
what is the bond enthalpy on a carbon to carbon double bond?
+612 kJ mol-1
92
is a double bond or a single bond more likely to break during a chemical reaction?
double bond
93
are carbon to carbon double bonds electron rich?
yes
94
are alkanes or alkenes more reactive?
alkenes
95
what is the equation for a typical addition reaction for alkenes?
unsaturated alkene plus reactant equals saturated product
96
what is the world equation for the hydrogenation of ethene?
unsaturated ethene plus water equals unsaturated ethane
97
what are the conditions needed for the hydrogenation of ethene?
nickel catalyst
150 degrees Celsius
98
what is the word equation for the halogenation of ethene with chlorine?
ethene plus chlorine equals haloalkane
99
what are the conditions needed for the halogenation of ethene with chlorine?
room temperature
100
what is the test for unsaturation?
bromine water turns from orange to colourless when reacting with an alkene?
101
are alkanes unreactive?
yes
102
what does the alkene have to be for there to be wo products?
unsymmetrical
103
what are the conditions needed for the hydration of alkenes?
alkenes will react with steam, H2O in the presence of phosphoric acid to produce alcohols
104
what is the typical addition reaction for an alkene called?
electrophilic addition
105
what is an electrophile?
electron pair accepter
106
what is heterolytic fission?
the breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (+ion) and an anion (-ion)
107
what is Markownikoff's rule?
the product depends upon the stability of the carbocation intermediate formed
the more stable the carbocation the more likely the product will be produced
108
if a primary and a secondary carbocation are formed, what will the main product be?
the secondary carbocation as it is more stable
109
what is the definition of polymerisation?
a process where small molecules called monomers join together into large molecules consisting of repeating units
110
what is addition polymerisation?
all the atoms in the monomer are used to form the polymer
111
how do you draw an addition polymerisation equation?
small n on the left hand side of the alkene
arrow
brackets around product with arms sticking out and a small n in the bottom right hand corner
112
What is a hydrocarbon?
A compound consisting of hydrogen and carbon only.
113
Define saturated hydrocarbons.
Contain single carbon-carbon bonds only.
114
What characterizes unsaturated hydrocarbons?
Contains a C=C double bond.
115
What does a molecular formula show?
The actual number of each type of atom.
116
What is an empirical formula?
Shows the simplest whole number ratio of atoms of each element in the compound.
117
Define general formula in organic chemistry.
Algebraic formula for a homologous series, e.g., CnH2n.
118
What does a structural formula represent?
The arrangement of atoms in a molecule.
119
What is a displayed formula?
Shows all the covalent bonds present in a molecule.
120
When drawing organic compounds, how many bonds should each carbon have?
Each carbon should have 4 bonds.
121
What is the shape around the carbon atom in saturated hydrocarbons?
Tetrahedral with a bond angle of 109.5°.
122
What is a skeletal formula?
A simplified organic formula showing only the carbon skeleton and associated functional groups.
123
Define aliphatic compounds.
Compounds containing carbon and hydrogen joined in straight chains, branched chains, or non-aromatic rings.
124
What are alicyclic compounds?
Aliphatic compounds arranged in non-aromatic rings with or without side chains.
125
What defines aromatic compounds?
Contain a benzene ring.
126
What are homologous series?
Families of organic compounds with the same functional group and general formula.
127
What is a functional group?
An atom or group of atoms that causes similar chemical properties in different molecules.
128
What is the suffix for alkanes?
-ane.
129
What is the suffix for alkenes?
-ene.
130
What is the suffix for alcohols?
-ol.
131
What prefix is used for haloalkanes?
chloro-, bromo-, iodo-.
132
What is the suffix for aldehydes?
-al.
133
What is the suffix for ketones?
-one.
134
What suffix denotes carboxylic acids?
-oic acid.
135
What suffix is used for esters?
-oate.
136
Fill in the blank: The order of precedence for naming functional groups is: Carboxylic acids > _______ > ketones > alcohols > alkenes > halogenoalkanes.
aldehydes.
137
True or False: In compounds with multiple functional groups, the highest precedence group takes the prefix form.
False.
138
What is the first step in naming carbon chains?
Count the longest carbon chain and name appropriately
139
What prefix is used for a branched chain with one carbon?
-CH (methyl)
140
What is the prefix for a branched chain with two carbons?
-C2H5 (ethyl)
141
List the prefixes for carbon chains with 1 to 4 carbons.
* meth
* eth
* prop
* but
142
What is the rule for adding a suffix to a name when it starts with a vowel?
Remove the -e from the stem alkane name
143
Provide an example of a suffix starting with a vowel.
Propan-1-ol
144
What happens if the suffix starts with a consonant?
Do not remove the -e from the stem alkane name
145
Give an example of a suffix starting with a consonant.
Propanenitrile
146
How is the position of a functional group indicated?
By a number, counting from the end of the molecule that gives the functional group the lowest number
147
Which functional groups are always on carbon 1?
Aldehydes, carboxylic acids, and nitriles
148
When are numbers included in the name?
Only if they are needed to avoid ambiguity
149
What takes precedence in numbering, functional groups or branched chains?
Functional groups take precedence
150
What is the correct name for a compound with a double bond and a branched chain?
3-methylbut-1-ene
151
What prefixes are used for multiple functional groups in naming?
di-, tri-, tetra-, penta-, or hexa-
152
How are words and numbers separated in chemical names?
Words are separated by dashes and numbers by commas
153
What is the naming convention for alkenes?
The double bond will be between two carbons and use the lower number to show its position
154
What does E or Z indicate in alkene naming?
The type of stereoisomer
155
What suffix is used if more than one double bond is present?
diene or triene
156
How are haloalkanes named?
Class the halogen as a substituent and use the prefix -fluoro, -chloro, -bromo, or -iodo
157
What is the ending for alcohols in naming?
-ol
158
What is added to the stem name if there are multiple -OH groups?
di, tri
159
What takes priority in numbering when an -OH group is present?
The OH group has a higher priority than halogenoalkane and alkene groups
160
What is the correct naming for a compound with both an alkene and an -OH group?
The priority group gets the suffix and the OH is named with the prefix hydroxy-
161
Fill in the blank: The suffix -en for alkenes can go in front of other _______.
[suffixes]
162
What is the correct name for a compound with an -OH group and a higher priority functional group?
The higher priority group gets the suffix ending
163
What is the naming convention for a compound with two functional groups, one being an -OH and the other a higher priority group?
The higher priority group gets the suffix and the -OH can be prefixed as hydroxy-
164
What is the suffix for aldehydes?
-al
165
Where is the C=O bond located in aldehydes?
On the first carbon of the chain
166
What prefix is used if there are two aldehyde groups?
di-
167
What suffix do ketones end with?
-one
168
When do ketones require a number in their name?
When they have 5 or more carbon atoms
169
What prefix is used if there are two ketone groups?
di-
170
What is the name of the simplest aldehyde?
Ethanal
171
What is the suffix for carboxylic acids?
-oic acid
172
Is a number necessary for the carboxylic acid group?
No, it must always be at the end of the chain
173
What is the name for a carboxylic acid with two acid groups on both ends?
-dioic acid
174
What are the two parts of an ester's name?
The -yl part from the alcohol and -anoate from the carboxylic acid
175
What is an example of an ester?
methylpropanoate
176
What are structural isomers?
Same molecular formula, different structures
177
What are the types of structural isomerism?
* Chain isomerism
* Position isomerism
* Functional group isomerism
178
What are chain isomers?
Compounds with the same molecular formula but different carbon skeleton structures
179
What is an example of chain isomers?
* Pentane
* 2-methylbutane
* 2,2-dimethylpropane
180
What are position isomers?
Same molecular formula, different positions of the same functional group
181
Give an example of position isomers.
* 1-bromopropane
* 2-bromopropane
182
What are functional group isomers?
Same molecular formula, different functional groups
183
Provide an example of functional group isomers.
* Methoxymethane (an ether)
* Ethanol (an alcohol)
184
What is the general formula for alkenes and cycloalkanes?
They have the same general formula
185
What is the process called when each atom gets one electron from the covalent bond?
Homolytic fission
## Footnote
Homolytic fission forms two free radicals.
186
What are Free Radicals?
Reactive species with an unpaired electron
## Footnote
Free Radicals do not have a charge and are represented by a •.
187
What occurs during Heterolytic fission?
One atom gets both electrons from the bond
## Footnote
Heterolytic fission produces ions.
188
What do most organic reactions occur via?
Heterolytic fission
## Footnote
This process produces ions.
189
What is the purpose of drawing mechanisms in organic chemistry?
To show in detail how a reaction proceeds
## Footnote
Mechanisms help visualize the steps of a reaction.
190
What do curly arrows in mechanisms represent?
Movement of an electron pair
## Footnote
Curly arrows indicate breaking or formation of a covalent bond.
191
From where does a curly arrow always start?
From a lone pair of electrons or the center of a bond
## Footnote
This indicates the source of the electron pair movement.
192
Fill in the blank: A Free Radical is a reactive species which possesses an _______.
unpaired electron
193
True or False: Heterolytic fission produces free radicals.
False
## Footnote
Heterolytic fission produces ions, not free radicals.
194
What charge does the carbon have in the given mechanism due to electronegativity difference?
Small positive charge
## Footnote
This occurs because of the difference in electronegativity between carbon and the halogen.
195
What are alkanes and cycloalkanes classified as?
Saturated hydrocarbons
196
What type of bond is formed in alkanes between carbon atoms?
Sigma bond
197
What is the shape around the carbon atom in saturated hydrocarbons?
Tetrahedral
198
What is the bond angle in alkanes?
109.5 degrees
199
What causes the increasing boiling points in the alkane homologous series?
Increasing number of electrons causing increased induced dipole-dipole interactions (London forces)
200
How do long chain alkanes compare to branched alkanes in terms of boiling points?
Long chain alkanes have stronger induced dipole-dipole interactions and higher boiling points
201
What explains the low reactivity of alkanes with many reagents?
High bond enthalpies of C-C and C-H bonds and very low polarity of sigma bonds
202
What is the definition of a fuel?
Releases heat energy when burnt
203
What are the products of complete combustion of alkanes?
CO and H2O
204
What occurs during incomplete combustion of alkanes?
Produces CO and/or C
205
What is a dangerous consequence of incomplete combustion?
Production of carbon monoxide (CO), which is toxic
206
What is cracking in the context of hydrocarbons?
Conversion of large hydrocarbons to smaller molecules by breaking C-C bonds
207
What are the conditions for catalytic cracking?
Slight pressure and high temperature (450°C)
208
What type of hydrocarbons does catalytic cracking produce?
Branched and cyclic alkanes, and aromatic hydrocarbons
209
Why is catalytic cracking economically beneficial?
Shorter C chain petroleum fractions are in more demand than larger ones
210
What catalyst is used in catalytic cracking?
Zeolite catalyst
211
Fill in the blank: Alkanes readily burn in the presence of _______.
Oxygen
212
True or False: Carbon monoxide is an odourless gas that can cause death in enclosed spaces.
True
213
What is the effect of carbon (soot) on the environment?
Causes global dimming by reflecting the sun's light
214
What is steroisomerism?
A form of isomerism where molecules have the same molecular formula but different spatial arrangements of atoms.
215
What are substitution reactions of alkanes?
Reactions where hydrogen atoms in alkanes are replaced by halogen atoms.
216
What is the synthesis of chloroalkanes?
The process of converting alkanes into chloroalkanes by substituting hydrogen with chlorine.
217
What happens when alkanes react with bromine or chlorine in UV light?
They form a mixture of products with halogens substituting hydrogen atoms.
218
What is the overall reaction for methane reacting with chlorine?
CH₄ + Cl₂ → CH₃Cl + HCl
219
Why do alkanes generally not react with many reagents?
Because the C-C and C-H bonds are relatively strong.
220
What is the mechanism called for the reaction of alkanes with halogens?
Free radical substitution.
221
What are the three steps in the free radical substitution mechanism?
* Initiation
* Propagation
* Termination
222
What occurs during the initiation step of the free radical substitution?
UV light breaks the Cl-Cl bond, forming chlorine free radicals.
223
Define a free radical.
A reactive species which possesses an unpaired electron.
224
What happens during the propagation step?
Chlorine free radicals react with methane and regenerate Cl free radicals.
225
What is the termination step in the free radical substitution?
The collision of two free radicals that does not generate further free radicals.
226
What is the essential condition for the initiation step?
UV light.
227
Provide the initiation reaction for bromine.
Br₂ → 2Br*
228
What is the overall reaction equation for the formation of CCl₃ from CH₄ + Cl₂?
CH₄ + 4 Cl₂ → CCl₄ + 4 HCl
229
Fill in the blank: In the presence of excess Cl, further substitution can produce _______.
CH₂Cl₂, CHCl₃, CCl₄
230
What is a minor step in the termination process that can lead to impurities?
The formation of ethane.
231
What happens when a halogen is substituted onto a middle carbon in the alkane chain?
The free radical dot must be placed on the correct carbon during propagation.
232
What is always the side product in these reactions?
HCl
233
What is the general formula for alkenes?
CnH2n
234
What type of bond exists in alkenes?
Carbon-carbon double bond
235
What components make up a C=C double bond?
* One sigma (σ) bond
* One pi (π) bond
236
What type of hydrocarbons are alkenes?
Unsaturated hydrocarbons
237
Why must numbers be added to the names of alkenes?
When positional isomers can occur
238
What is the bond angle around the C=C double bond in alkenes?
120°
239
What is the characteristic structure of the π bond in alkenes?
Formed by sideways overlap of two p orbitals
240
What are electrophiles?
Species that 'like' electrons and can attack π bonds
241
True or False: Rotation can occur around a pi bond.
False
242
What is stereoisomerism?
Same structural formulae but different spatial arrangement of atoms
243
What is E-Z stereoisomerism?
A type of isomerism due to restricted rotation about the C=C bond
244
What leads to the existence of E-Z isomers?
Two different groups/atoms attached at both ends of the double bond
245
Fill in the blank: But-1-ene is a structural isomer of ______.
But-2-ene
246
What does the 'Z' in Z-but-2-ene indicate?
Priority atoms are on the same side of the double bond
247
What does the 'E' in E-but-2-ene indicate?
Priority atoms are on opposite sides of the double bond
248
What are Cahn-Ingold-Prelog (CIP) priority rules used for?
Determining priority groups on both sides of the double bond
249
How do you determine the priority of atoms in CIP rules?
* Compare atomic numbers of atoms directly attached to each side
* If same, consider atoms at distance 2 from the double bond
250
What is the significance of having different groups attached to a double bond?
Leads to the formation of E-Z isomers
251
What happens if two identical groups are attached to one end of a double bond?
No E-Z isomers exist
252
What is cis-trans isomerism?
A special case of ElZ isomerism where two of the substituent groups are the same
253
What is another name for Z-but-2-ene?
Cis-but-2-ene
254
How do E-Z stereoisomers differ in terms of physical properties?
They can have differing melting and boiling points
255
What is another name for E-but-2-ene?
Trans-but-2-ene
256
What is the boiling point of Z-1,2-dichloroethene?
60°C
257
Why is Z-1,2-dichloroethene considered polar?
The polar C-Cl bonds are on the same side of the molecule, creating a slight negative charge
258
What intermolecular forces are present in Z-1,2-dichloroethene?
* London forces
* Permanent dipole-dipole attractions
259
What is the boiling point of E-1,2-dichloroethene?
48°C
260
Why is E-1,2-dichloroethene considered non-polar?
The polar C-Cl bonds are on opposite sides of the molecule, causing the dipoles to cancel out
261
What intermolecular forces are present in E-1,2-dichloroethene?
* Only London forces
262
What type of reaction occurs when alkenes react with hydrogen?
Addition reaction
263
What is the change in functional group when alkenes react with hydrogen?
Alkene → Alkane
264
What are the conditions required for the reaction of alkenes with hydrogen?
Nickel catalyst
265
What is the type of reaction when alkenes react with hydrogen?
Addition/reduction
266
What type of reaction occurs when alkenes react with bromine or chlorine?
Electrophilic Addition
267
What is the change in functional group when alkenes react with bromine?
Alkene → Dihaloalkane
268
What are the conditions for the reaction of alkenes with bromine?
Room temperature (not in UV light)
269
What type of bond fission occurs in the reaction of alkenes with bromine?
Heterolytic
270
What does the term 'electrophile' refer to?
An electron pair acceptor
271
What is formed as an intermediate when alkenes react with bromine?
Carbocation
272
What is the change in functional group when alkenes react with hydrogen bromide?
alkene → haloalkane
273
What are the reagents used in the reaction of alkenes with hydrogen bromide?
HCl or HBr
274
What are the essential conditions for the reaction of alkenes with HBr?
Room temperature
275
What is the mechanism of the reaction between hydrogen bromide and alkenes?
Electrophilic Addition
276
What type of reagent is hydrogen bromide in the context of this reaction?
Electrophile, H+
277
What is the significance of the polar nature of HBr in the reaction with alkenes?
The H+ is attracted to the electron-rich pi bond.
278
What does Markownikoff's Rule state regarding the addition of hydrogen bromide to unsymmetrical alkenes?
It can lead to two isomeric products.
279
Why is one carbocation intermediate more stable than another during the electrophilic addition to alkenes?
Methyl groups on either side of the positive carbon are electron releasing and reduce the charge on the ion.
280
What is the order of stability for carbocations?
tertiary > secondary > primary
281
What is the industrial method used to convert alkenes to alcohols?
Reaction with steam in the presence of an acid catalyst
282
What is the chemical equation for the hydration of ethene?
CH2=CH2 (g) + H2O (g) → CH3CH2OH (l)
283
What are the essential conditions for the hydration reaction of alkenes?
High temperature (300 to 600°C), High pressure (70 atm), Catalyst of concentrated H3PO4
284
Define addition polymerisation.
The process of forming addition polymers from alkenes.
285
What is the repeating unit in polyethene derived from ethene?
H2C-CH2
286
What is the process for recycling poly(propene)?
Sorting and remoulding the waste
287
What is the industrial significance of hydrogenation of unsaturated vegetable oils?
It converts double bonds to saturated single bonds, increasing melting point.
288
How can waste polymers be processed?
Separation and recycling, Feedstock for cracking, Combustion for energy production
289
What environmental issue can arise from the combustion of halogenated plastics?
Formation of toxic, acidic waste products such as HCl.
290
What types of polymers are being developed to minimize environmental damage?
Biodegradable, compostable, soluble, and photodegradable polymers.
291
What are examples of biodegradable polymers?
Polymers formed from isoprene, maize, and starch.
292
What is a benefit of combusting waste?
Less landfill
293
What is a negative of combusting waste?
CO2 and toxic gases released
294
What are benefits of biodegradable and photodegradable polymers?
Less landfill
Soil will receive nutrients
295
What is a negative of photodegradable and biodegradable polymers?
Could cause food shortage as they are both made from plants
