Chem - Organic chem SL&HL Flashcards

1
Q

What is Organic Chemistry

A

Field of chemistry which studies carbon-based compounds

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2
Q

What is a homologous Series

A
  • a series of compounds of the same family, with the same general formula, which differ from each other by a common structural unit.
  • homologous series which contain functional group also have similar physical and chemical properties within the series.
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3
Q

Physical properties of homologous series

A

as length of the chain increases:
- the boiling point increases
- increase in SA
- greater chance of intermolecular bonding
- more energy to break bonds

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4
Q

IUPAC - root names, based off of number of C atoms

A

1 Cabon: meth-
2 Carbon: eth-
3 Carbon: prop-
4 Carbon: but-
5 Carbon: pent-
6 Carbon: hex-
7 Carbon: hept-
8 Carbon: oct-

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5
Q

IUPAC - identifying the type of bonding in chain or ring

A

a. all single bonds: -an-
b. one double bond: -en-
c. one triple bond: -yn-

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6
Q

IUPAC - identify functional or alkyl group

A

Alkane: -e
Hydroxyl: -ol
Amine: amino-
Amide: -amide
Nitrile: -nitrile
Halo: chloro-,bromo-, iodo-
Aldehyde: -al
Ketone: -one
Carboxylic Acid: -oic acid
ether: -oxy-
ester: -oate-

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7
Q

what is the last step of IUPAC naming?

A

use numbers to give position of groups or bonds along chain, always choosing the lowest number

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8
Q

Primary compounds

A

C-atoms bonded to functional group is also bonded to ONE other C-atom

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9
Q

Secondary compounds

A

C-atom bonded to functional group is also bonded to TWO other C-atoms

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10
Q

Tertiary compounds

A

C-atom bonded to functional group is also bonded to THREE other C-atoms

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11
Q

Alkanes

A

Hydrocarbons
- contain hydrogen and carbon only
CnH2n+2
- only single bonded
- saturated
- “-ane”

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12
Q

Alkenes

A

Hydrocarbons
- contain hydrogen and carbon only
CnH2n
- double bond
- unsaturated
- “-ene”
- position of double bond must be specified
-functional group: alkenyl

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13
Q

Alkynes

A

Hydrocarbons
- contain hydrogen and carbon only
CnH2n-2
- triple bond
- unsaturated
- “-yne”
- position of triple bond must be specified
-functional group: alkynyl

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14
Q

Arenes

A

Hydrocarbons
- contain hydrogen and carbon only
CnHn
- collective name given to compounds with one or more rings with pi electron that are delocalised throughout the rings
- functional group: phenyl
- Benzene

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15
Q

Halogenoalkanes

A

CnH2n+1X
- X - halogen
- “chloro-“, “bromo-“, “iodo-“
- “-ane”
- position of the halogen must be specified by numbering the Carbon
- if there is more than on of each halogen - di,tri or tetra must be used

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16
Q

Alcohols

A

functional group: -OH, hydroxyl
- CnH2n+1OH
- “-ol”
- primary,secondary, tertiary

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17
Q

Ethers

A

functional group: R – O –R, ether
- CnH2n+2O
- each R-group is given an alkyl name
“-ane”

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18
Q

Carbonyls

A

functional group: C=O
- CnH2nO
- subfamilies: aldehyde and ketone

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19
Q

Aldehydes

A
  • when carbonyl group is a tthe end of the chain
    functional group: -RCHO
  • “-al”
  • will always be on number 1 carbon
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20
Q

Ketones

A

-minimum of 3 carbons
functional group: RCOR
-“-one”
- # for carbon must be used

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21
Q

aldehydes vs ketones

A

show similar chemical reactions - similar functional groups arrangments
differences in chemistry are due to the involvements of the H in aldehyde or nature of R group
differences in electronegativity between C=O menas its polar
- dipole attraction between molecules
- higher boiling point
-solubiliyt in water

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22
Q

Carboxylic acid

A

functional group: carboxyl, -COOH
-CnH2n+1COOH, RCOOH
- “-oic acid”

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23
Q

Esters

A

functional group: carboxylate, -COOR
- RCOOR
- “-oate”
alkyl + alkanoate
e.g. methyl ethanoate

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24
Q

carboxylic acids vs esters

A

contain similarities in chemical and physical properties
- H-bonds are present between carbpxylic acid molecules, and not between esters.
- this affects melting, boiling ang solubility
- carboxylic acids: smaller chain are soluble in water and have higher melting points
- esters: insoluble in water and have lower boiling points than carboxylic acids

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25
Q

Amines

A

functional group: -NH2
-CnH2n+2NH2, RNH2
“amino+alkane”

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26
Q

Amides

A

functional group: carboxamide, -CONH2
combination of amino and carbonyl groups
- CnH2n+1CONH2, RCNH2
- “-amide”

27
Q

Nitriles

A

functional group: nitrile, -CN
-CnH2n+1CN, RCN
-“-nitrile”

28
Q

what symbolises a bond going away from you in a stereochemical drawing

A
29
Q

what symbolises a bond going towards you in a stereochemical drawing

A
30
Q

Why are alkanes unreactive?

A

Strength of C-H bonds
- alkanes consist of C and H bonded by single bonds
- without heat, it’s hard to break these strong C-C and C-H covalent bonds

Lack of polarity
- electronegativites of C and H are almost similar
- electrons shared equally
- alkanes don’t react with polat reagents, as they have no nucleophilic or electrophilic areas

alkanes only react in combustion reactions and undergo substitutions by halogens

31
Q

Complete combustion of Alkane

A

when alkanes are burnt in XS O2, complete combustion takes plane, and all C and H will oxidise to CO2 and H2O

32
Q

Incomplete combustion of Alkane

A

when alkanes are burnt in limited supply of O2, incomplete combustion will take place and not all C-atoms fully oxidise.
Alkane + Oxygen –> CO + H2O

CO is a toxic gas, will bind to haemoglobin in blood which can then no longer bind to O2
CO is odorless, and found in car engines where O2

33
Q

Free radical sustitution

Steps 1-3

A

alkanes - halogenations
u.v. light (sunlight) is needed
a hydrigen atom gets substitutes by a halogen
1. inititation step
- Halogen bond is broken by UV energy to form two radicals
- produces two radical in a homolytic fission reaction

  1. propegation step
    - progression of the substitution reaction in a chain type reaction
    - free radicals are very reactive, and will attack unreactive alkanes
    - a C-H bond breaks homolytically ( each atom gets an e- from covalent bond)
    - an alkyl free radical is produced
    - which can attack another halogen to form halogenoalkane and regenerate the halogen bond
    - this reaction is not verys uitable for preparing specific halogenoalkanes as a mixture of substitution products are formed
    - if there is enough halogens present, all the hydrigens in the alkane will eventually substituted
  2. termination step
    - when the chain reaction terminates due to two free radicals reacting together and forming a single unreactive molecule
    - multiple products possible
34
Q

reactivity of alkenes

A

C=C bonds gives alkanes a number of chemical properties not seen in alkanes
- alkenes contain pi-bonds, it is possible to break the weaker pi-bonds and form stronger σ bonds with other species withoit forcing any atom on the molecule to break off
- alkenes are able to undergo substitutions
- can undergo addition
- unsaturated
- addition reactions are faster than substitution reaction as only weak pi-bonds are broken rather than σ bonds.

35
Q

What is the test for unsaturated alkenes?

A

Br2 - yellow, orange solution, “bromine water”
- unknown molecule/compound is shaken with bromine water
- if compound is unsaturated - addition will take place and color is lost

36
Q

Alkenes Halogenation

A

electrophilic addition - more detail in other flashcard
- C=C doubel bond is broken, and a new single bond is formed from each of the two C atoms
- occurs at room temperature
- halogens can be used to test if molecule is unsaturated

37
Q

electrophile

A

‘electron seeker’
has a positive charge

38
Q

nucleophile

A

‘wants to give away electrons’
negative charge

39
Q

Alkenes Hydration

A
  • when alkenes are reacted in steam at 300°C, pressure at 60 atm, and sulfuric acid/phosphoric acid catalyst, water is added to the double bond
  • alkene —> alcohol
  • reaction processes via an intermediate in which H+ and H2SO4- ions are added. across double bond
  • the intermediate is quickly hydrolyseed by water, reforming H2SO4
40
Q

Addition Polymers

A
  • most important addition reaction of alkenes
  • is the reaction in which many monomers containing at least one C=C double bond form long chain of polymers as the only product
  • the pi-bond in each C=C breaks and monomers link together to form C-C
  • polymer - long chain that is made up of repeating units
  • small, reactive molecules that react together to from the polymer are called monomers
41
Q

how do you deduce repeating units in polymers

A
  • repeated unit is the smallest group of atoms that when connected one after the other make up the polymer chain
  • square brackets
  • in poly(alkenes) and substituted poly(alkenes) made up of one type of monomer the repeating unit is the same as the monomer except that the C=C double bond is changed to C-C
42
Q

complete combustion of alcohols

A
  • Alcohol + Oxygen —> CO2 and H2O
  • lower alcohols burn with an almost invisible flame and make good fuels
  • ethanol can be produced sustainably as a fuel by the fermentation of sugars
  • ethanol has a lower energy density is lower than gasoline, therfore blending ethanol and gasoline increases energy denisty, makes it safer in case of fires as the flames can be seen
43
Q

Oxidation of Primary Alcohol

A

oxidise to form aldehydes and then carboxylix acids
oxidising agents: K2Cr2O7 or KMnO4
Potassium dichromate: K2Cr2O7
- orange
- in a solution of dilute acid
- orange Cr2O7 (2-) ions–> greenCr (3+) ions
Potassium Manganate: KMnO4
- purple
- in a solution of dilute acid
- purple MnO4(-) ions –> colorless Mn(2+)
In XS Oxidising agents, if the aldehyde produced isn’t distilled off, it will further oxidise to carboxylic acids, however this reaction takes some time to complete and requires heating.

Tests for alcohols:
- oxidation using acidified dichromatic provides basis for the test for alcohols as it shows color change
- orange –> green
- does not work for tertiary alcohols

44
Q

Oxidation for secondary alcohols

A
  • oxidise to ketones
  • under sustained heating
45
Q

Oxidation for tertiary alcohols

A
  • DO NOT undergo oxidation
  • there are only C-C bonds on functional group carbon in tertiary alcohols
  • no H that can break off to form water
46
Q

distillation vs heating under reflux

A
47
Q

Alcohols esterifications

A

ester: -COOR, sweet, fruity smell
- formed via condensation reactions between Crboxylic acids and Alcohols, with concentrated H2SO4 as catalyst
esterification : NUCLEOPHILLIC SUBSTITUTION
naming ester: first part of alcohol, second part: carboxylic acid

48
Q

Reactions of Halogenoalkanes

A
  • much more reactive than alkanes due to presence of electronegative halogens
  • X-C bond is polat, C - carries partial + charge, X - carries partial - charge
    Nucleophilic substitutions with NaOH
  • halogenoalkane + aq alkali –> alcohol
  • OH- behaves as nucleophile by donating a pair of e- to - C-atom bonded to halogen
  • reaction is slow at room temp.
  • high yield when heated under reflux
49
Q

Reactions of Benzene

A

Arenes are very stable compounds due to delocalisation of pi e- in the ring,
- e- density is spread ou over the molecules
during substitution: ring is maintained
during addition: aromatic stabilisation is disturbed so it’s not favored

50
Q

electrophilic substitution with benzene

A

with Cl2 or Br2 in the presence of anahydrous AlCl3 or AlBr2 catalysts to form halogenoarene
- cl/br acts as electrophile and replaces H atom in benzene
- catalyst necessart due to stability of benzene structure
- alkylarenes such as methylbenzene undergo halogenation on the 2 or 4 position, which is due to e- donating alkyl group which activates these positions.
- ∴the halogenation of alkylarenes results in the formation of 2 products
- in xs halogen, it joins at the 2 or 4 or 6 positions
-

51
Q

Nitration of Benzene

A
  • substitution
  • a nitro (NO2) group replaces H atom on arene
  • benzene is reacted with mixture of conc. nitric acid and conc. sulfuric acid at 25-60℃
  • occurs at 2 and 4 positions
52
Q

Nucleophilic Substitutions (HL)

A
  • organic reaction in which nucleophile attacks a carbonyl C-atom with partial + charge.
  • atom attaches to carbonyl has a -charge and is replaces by nucleophile
  • involves halogenoalkanes, the halogen is replaced by nucleophile
  • the OH-, is stronger nucleophile than H2O, bc it has a full - charge
  • strength of nucleophile depends on it’s abolity to make its e- pairs available for reactions
    in general:
  • charged ions > neutral atom
    conjugate base > conjugate acid
    OH->H2O
53
Q

SN1 (w Arrows)

A
  • tertiary halogenoalkanes - C attached to halogen i salso bonded to 3 alkyl groups
    1 stands for the rate of reaction
    SN1 is 2 steps
    First step:
  • C-X bond breaks heterotically and the halogen leaves the halogenoalkane as an X- ion
  • slow, rate determining step
  • only depends on the conc. of halogenoalkane
  • rate= k(halogenoalkane)
  • forms a tertiary carbocation ( tertiary C with + charge)
    Second step:
  • the tertiary carbocation is attacked by nucleophile
54
Q

Heterolytic fission

A

forms anions and cations and used double headed arrows to show movement of both e- from covalent bonds

55
Q

Homolytic fission

A

forms free radicals and uses single headed arrows, “fish hooks”, to show the moevement of a single e- as a covalent bond breaks

56
Q

SN2

A
  • Primary halogenoalkanes, the C attached to the halogen is bonded to one alkyl group
    2 stands for rate of reaction
    SN2 is one step reaction
  • nucleophile donates a pair of e- to the g+ C atom of the halogenoalkane to form a new bond
  • rate determining step depends on the conc. halogenoalkane and nucleophile
  • rate=k(halogenoalkane)(nucleophile)
  • at the same time, the C-X bond breaks and the halogen takes both e- in the bond
  • the halogen leaves the halogeno alkane as X- ion
  • nucleophile can only attack from oppisite direction of C-X bond
  • as C-Nucleophile bond forms, C-Br bond breaks causing X atom to leave as an ion.
57
Q

What factors affect SN1 and SN2

A
  1. nature of nucleophile
  2. halogen involved
  3. the structure (class) of halogenoalkane
  4. protic and aprotic solvents
58
Q

How does the nature of the nucleophile affect SN1&2

A

most effective nucleophiles are neutral or - charged species, that have lone pair of e- avaliable to donate to the g+ C in halogenoalkane
- greater the e- density on the nucleophile ion or molecule – the stronger the nucleophile
- when nucleophiles have some charge, the electronegativty of the atom carrying the lone pair becomes the deciding factor
- less electronegative the atom = stronger nucleophile
- less electronegative atom has a weaker grip on lone pairs e-

59
Q

How does the halogen involved affect SN1&2

A
  • the halogenoalkane have different rates of substitution reactions
  • C-I bond is the weakest and easiest to break
  • C-F bond is the strongest and hardest to break
  • floroalkanes –> chloroalkanes –> bromoalkanes –> iodoalkanes
  • least reactive –> most reactive
60
Q

how does the structure of the halogenoalkane affect SN1&2

A
  • tertiary halogenoalkane –> SN1, forms stable tertiary cabocations
  • -secondary –> mixture of SN1 and 2, forming less stable primary carbocations
  • this has to do with + inductive effect of alkyl group attached to C-X
  • tertiary carbocation - 3 alkyl groups
  • primary - 1 alkyl group, less stable
61
Q

How do protic and aprotic solvents affect SN1&2

A

Protic solvents
- contain a H atom bonded to electronegative N or O
- capable of hydrogen bonding

Aprotic solvents
- contain H atom but not bonded to eelctronegative atom
- cannot participate in H-bonding

SN1 - best conducted using protic, polar solvents
SN2 - best conducted using aprotic, non-polar solvents

62
Q

Electrophilic Addition

A

addition of an electrophile (lewis acid) to an alkene double bond, C=C
- C=C , is an area of high electron density which makes it susceptible to attack by electrophiles
- C=C bond breaks forming a C-C bond and 2 new bonds

Electrophiles
- H2(g)–> alkane
- H2O(g) –> alcohol
- HX, hydrogen halides –> halogenoalkane
- X2, halogen –> dihalogenoalkane

63
Q

Electrophilic addition of HX

A