CHAPTER 1: ORGANIC COMPOUNDS
NOTE: I highly recommend that you do the practice questions to help you learn. If you can’t explain it, you don’t know it!
Key Ideas: see p 6. Read Introduction.
Organic compounds: carbon is the principle element
1.1: Functional Groups.
- active areas of the molecule
- determine the physical and chemical properties
- each organic family has its own functional group
- 3 components: 1. ________________________________________________________________
2. ________________________________________________________________
3. ________________________________________________________________
Carbon-Carbon multiple bonds:
- single bonds C-C are strong
- a second or third bond is less strong C=C or CC so a reaction that breaks the second or the second
and third is likely
Single Bonds between C and a more electronegative atom:
- ex: O, N, F, Cl, Br
- bond is polar, so attraction among molecules increases, so mp and bp go up
- if C-O-H or C-N-H, the H is very positive so very polar so even higher mp and bp
and ability to dissolve in polar solvents like water (like dissolves like)
Double-Bonded C and O
- C=O means the bond is more polar than C-O so increase in mp and bp and more ability to dissolve in
polar solvents
1.2: Hydrocarbons:
Aliphatic hydrocarbons: ______________________________________________________________
-
alkanes: _______________________________________________________________________
-
alkenes: _______________________________________________________________________
-
alkynes: ________________________________________________________________________
Aromatic hydrocarbons: _______________________________________________________________
see p 11 table 1
Nomenclature of Hydrocarbons: ( IUPAC )
Alkanes: suffix “-ane”
branch chain: suffix: “-yl”
- know forst 10 prefixes – see p 12 table 2
Isomers - __________________________________________________________________________
-
see Summary of naming, p 15
Alkenes and Alkynes: suffixes “-ene” and “-yne”
- see summary p 18
Aromatic Hydrocarbons:
- benzene is the parent, alkyl groups atached
- if the side chain isn’t attached to the benzene ring on the end C, then the chain may be the parent and
the benzene ring the attachment – called the phenyl group
- see summary p 21
Physical Properties of Hydrocarbons:
1. low mp and bp –
2. the smaller the molecule, the lower the mp and bp
3. non-polar – C and H have almost the same electronegativities and so form non-polar bonds
4. make good non-polar solvents
5. don’t dissolve in polar solvents such as water
1.3: Reactions of Hydrocarbons
- all burn to give CO2, H2O and huge amounts of heat energy
- less reactive - Alkanes  aromatic compounds  alkenes  alkynes – more reactive
Reactions of Alkanes:
- single C-C bonds stable and so unreactive, generally
- combustion
- Substitution reactions – add halogen gas, one H is replaced with one halogen  alkyl halide + acid
and if excess halogen gas is present, further substitutions can happen
Reactions of Alkenes and Alkynes:
- Addition reactions: the double / triple bond is broken and an atom is added to each C :
1. add halogen get alkyl compound with 2 halogens ( halogenation )
2. Hydrogenation: add hydrogen gas, get alkane
- unsaturated fats – have alkyl groups with many double bonds – lower mp
- saturated fats – hydrogenation reactions – get fats with higher mp
3. add hydrogen halide and get alkane with single halide
4. Hydration: add water, get alkane with OH group – an alcohol
- Markovnikov’s Rule: “ the rich get richer” – if addition reaction with non-identical atoms being added,
the H gets added to the C that already has more H’s attached to it
Reactions of Aromatic Compounds:
- Substitution reactions: H replaced with another group
- due to nature of bonds in benzene ring: e- shared equally by all 6 C’s, so bonds between C’s are
stronger and shorter than single C-C bonds but longer and less strong than C=C bonds.
- typical “resonance” structure
- see Summare p 30
1.4: Organic Halides
- one or more H’s replaced with a halogen atom
- naming – see p 32
Properties of Organic Halides
- Halogens have higher electronegativity than H so C-X bonds more polar
- so substances have higher mp and bp
- and more able to dissolve in polar solvents than alkanes
- molecules with 2, 3 or more halogen atoms may be formed when halogen gas is added to alkanes
- the greater the number of halogen atoms, the more polar the molecule, the higher the mp and bp, so
they can be separated
- see table 1 p 34
The Cost of Air Conditioning
- refrigerants – CFC’s such as CF2Cl2
- stable , but decompose in upper atmosphere under UV light
- release Cl atom – reacts with ozone to form O2
- one Cl atom can decompose 1 000 000 molecules of ozone
- new compounds now used: HCCl’s and HCF’s – presence of H causes less stable compound when
released into atmosphere
- these decompose more quickly and at lower atmosphere levels so less ozone is affected
- drawback: CO2 produced when HCF’s decompose – adding to greenhouse gases
Preparing Organic Halides – addition reaction to alkenes or alkynes
- substitution reaction with benzene
Preparing Alkenes from Alkyl Halides
- Elimination Reaction: alkyl halide in a base ( hydroxide ion )  alkene + water + halide ion
- see summary p 36
1.5: Alcohols and Ethers
Alcohols:
- contain OH group – hydroxl group
- ex: ethanol – alcohol in drinks, poisonous, depressant see p 38: Alcohol toxicity
- retinol – Vitamin A
Naming Alcohols
- end in “-ol”
- or: OH group is considered to be added to the parent chain : 2-hydroxybutane instead of 2-butanol
1o, 2o, 3o Alcohols:
- primary – OH is on an end C – most reactive kind
- secondary – OH is attached to a C that is attached to 1 other C
- tertiary – OH is attached to C that is attached to 2 other C’s
Polyalcohols:
- 2 or more OH groups
- use alkane plus “-diol” or “-triol” …
- ex: antifreeze – commonly called ethylene glycol – 1,2-ethanediol, it’s soluble in water, sweet-tasting
ad poisonous – wash away spills outside – cats and dogs die!
- ex: glycerol ( glycerine) 1,2,3-propanetriol, non-toxic, very soluble in water, used in lotions and
chocolate
- ex: sugars have OH groups
Cyclic Alcohols:
- based on cycloalkanes: ex menthol and chlosterol
- based on benzene: ex phenol
- use hydroxyl prefix for naming
Properties of Alcohols
- bp higher than parent alkanes – due to polarity
- smaller ones much more soluble in water than parent alkanes – due to polarity
- if alkyl chain is long, then non-polar substances will dissolve in the alcohol
Reactions involving Alcohols:
- preparation: hydration of an alkene
- Combustion: form CO2 and water
- from alcohol to alkene: Elimination reaction with conc. H2SO4 ( dehydration ) summary – see p 45
Ethers:
- first used as an anesthetic
Properties of Ethers:
- two alkyl groups attached to an oxygen
- alkyl groups may be the same or different
- C-O-C bond is v-shaped and polar, so molecule is more polar than an alkane with the same number of
C’s but not as polar as alcohols with the O-H bond
- see table 2 p 46
- can dissolve both polar and non-polar substances
- C-O bond stable so they are unrreactive
Naming Ethers:
- use “-oxy” on end of shorter alkyl group as prefix to larger alkyl group
- ex: ethoxybutane for: CH3CH2-O-CH2CH2CH2CH3
- or name the two alkyl groups: ethyl butyl ether * three separate words this time
Preparing Ethers from Alcohols:
- Condensation reaction: 1 water molecule eliminated when 2 alcohol molecules combins
use conc. sulfuric acid as the catalyst
1.6: Aldehydes and Ketones:
- C=O gp called carbonyl gp
- Aldehyde: carbonyl gp on end C
- small aldehyde molecules smelly ex: formaldehyle and acetaldehyle stink and are preservatives
and disinfectants
- larger ones – flower smells ex: iol of almonds - benzaldehyhde
- Ketone: carbonyl gp not on end C
- insects can smell them from far away
- ex: ants follow trails, pheromones attract insect mates
- ex: propanone (acetone) is a good solvent
Naming Aldehydes and ketones:
- “-al” and “-one”
- number the C the =O is on for ketones
Properties of Aldehydes and ketones:
- lower mp and bp than alcohols but higher than the parent alkanes
- the C=O bond is polar
- can dissolve in both polar and non-polar substances so make good solvents
Preparing Aldehydes and Ketones from Alcohols: Oxidation Reactions
- oxidation reaction: _________________________________________________________________
- controlled oxidation reaction: H removed from the molecule and combines with oxygen to form water
- Oxygen supplied by oxidation reagents ex: KmnO4 and K2CR2O7, with conc sulfuric acid as a catalyst
- primary alcohols make aldehydes
- secondary alcohols make ketones
- tertiary alcohols don’t react – the C with the OH group doesn’t have aaa H to contribute
- see summary p 53
From Aldehydes and Ketones to Alcohols: Hydrogenation Reaction:
- add hydrogen to cause C=O bond to break and 2 H atoms added to make an alcohol
- C=O bond is strong – hydrogenatiiion needs high temp and pressure and a catalyst
- aldehydes make primary alcohols
- ketones make secondary alcohols see summary p 55.
1.7: Carboxylic Acids and Esters
Carboxylic Acids:
- weak acids
- ex: vinegar – when alcohol made by fermenting food is further oxidized
- ex: lactic acid – sour milk, and causes muscle pain when a build-up in the muscles after lots of
exercise
Naming Carboxylic acids:
- carboxyl group: COOH, combines hydroxyl group OH, and carbonyl group C=O
- “-oic acid “
- carboxyl group on either end of the alkane or alkene chain: “-dioic acid”
- ex: methanoic acid (formic acid) – in and ant bites bee stings, removes hair from hides
- ex: ethanoic acid ( vinegar, acetic acid), cooking, dying, solvent
- ex: phenylmethanoic acid (benzoic acid) – simplest aromatic acid – to make sodium benzoate to
preserve foods
- ex: oxalic acid, tartaric acid, citric acid, Vitamin C, acetylsalicylic acid, …..
Properties of Carboxylic Acids:
- carboxyl group is polar
- so mp and bp are higher than for parent alkanes
- all properties of non-organic acids – litmus pink, neutralize bases…
- react with organic “bases” (alcohols) to form organic “salts” (esters)
Preparing Carboxylic Acids:
- controlled oxidation of an alcohol to an aldehyde and then to a carboxylic acid
- ex: use potassium dichromate as a source of oxygen and the Cr ion goes from +6 to +6 and from
orange to green – the breathalyzer test!
- see summary p 62
From Carboxylic Acids to Organic “Salts”: Esterification
- carboxylic acid + alcohol, with conc sulfuric acid and heat, gives an ester – an organic salt
Esters:
give odours to fruits and flowers
see table p 64
Naming and Preparing Esters:
- are salts
- alkyl group from the alcohol + alkyl group from the acid”-oate” 2 words
- Condensation reaction: acid + alcohol  ester + water
Properties of Esters:
- don’t have the OH group so less polar than parent acids
- less soluble in water and lower mp and bp than parent acids
- no acidic properties
- smaller ones gases at room temp and so we can smell them
- larger ones are waxy
Reactions of Esters: Hydrolysis
- use strong base to break C-O bond and get back the acidic ion and alcohol
- fats are esters and when cooked with strong base becone the sodium salts of the fatty acids – soap
- summary: see p 67
1.8: Amines and Amides:
Amines:
- from NH3 where 1, 2, or 3 H’s are replaced by alkyl groups
- from breakdown of proteins by bacteria – smell bad
- 1o – primary – one alkyl group in place of one H on ammonia molecule
- 2o- secondary – 2 alkyl groups in place of 2 H’s on ammonia molecule
- 3o – tertiary – 3 alkyl groups
Naming Amines:
- “amino” prefix to the alkane ex: cadaverine is 1,5-diaminopentane
- or alkyl prefix to the “amine”
Properties of Amines:
- N-C bond and N-H bond are polar so amines have higher mp and bp, but lower than for alcohols
because N-C nad N-H bonds are less polar than O-C and O-H bonds
- dissolve in water
- small ones are gases at room temp and smell “fishy”
Preparing Amines:
- ammonia + alkyl halide – primary amine
- excess alkyl halide can lead to more substitutions to get secondary and tertiary amines as well
- see summary p 73
Amides:
- similar to esters – O is replaced by N
- amide bonds called peptide bonds in proteins – hold proteins together
Naming and Preparing Amides:
- Condensation reaction: acid + (ammonia or 1o or 2o amine)  amide + water
- alkyl from the amine + alkyl from the acid”-amide” 2 words
- see summare p 75
Properties of Amides:
- weak bases
- insoluble in water ( except smaller ones slightly soluble due to N-H bond )
- N bonded to 2 H’s higher mp and bp – polar bonds
Reactions of Amides:
- hydrolysis with bases ( or acids) to reform acids and amines
- happens less spontaneously than for esters
- good because means proteins hold together quite well – stable
- see summary p 78.
1.9: Synthesizing Organic Compounds:
- more kinds made daily to experiment or to fulfill an exact need
- read the rest for interest.
SUMMARY p 83 !! SUMMARY p 92 – 93
Problems you can solve p 94 – to help you study Self-Quiz: do it! answers in the back of the book
Problem Set: p 96 1, 2, 3 odds, 4, 5 odds, 6, 7 odds, 8 odds, 9, 10 odds, 11, 14, 15a,b,d.
(You should be able to do all parts of the questions where I required only the “odds”. )
Labs: 1.3.1 dry, 1.5.2 short,
1.7.2 full lab report,
1.9.1 short.