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Chem Mod 4 > Alcohols Haloalkanes And Analysis > Flashcards

Alcohols Haloalkanes And Analysis Flashcards

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1
Q

How do you name alcohols?

A

Propan-1-ol if -OH is on carbon 1

Propan-2-ol if -OH is on carbon 2

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2
Q

What are primary alcohols?

A

-OH group is attached to the end of an unbranched chain

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3
Q

What are secondary alcohols?

A

-OH group is attached to a carbon atom with two alkyl chains and one hydrogen atom

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4
Q

What are tertiary alcohols?

A

-OH group is attached to a carbon atom with 3 alkyl chains attached

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5
Q

What effect does the length of alcohol chains have on boiling point?

A

As molecules get longer there is more surface contact and so molecules have stronger induced dipole-dipole forces

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6
Q

How do boiling points of alcohols compare to those of alkanes?

A

Bp of alcohols are stronger than corresponding alkanes due to hydrogen bonds between -OH groups: strongest type of intermolecular force

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7
Q

What happens to the solubility of alcohols as their chain length increases?

A

Solubility decreases as chain length increases: aliphatic chain cannot form hydrogen bonds

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8
Q

What is produced when alcohols undergo complete combustion?

A

Water and carbon dioxide

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9
Q

How can you get an aldehyde through oxidation of an alcohol? State reagents and colour changes

A
  • react an oxidising agent with a primary alcohol
  • heated gently with acidified potassium dichromate
  • produces an aldehyde and water
  • orange to green
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10
Q

How can you get a carboxyl if acid through oxidation of an alcohol? State reagents and colour changes

A
  • react an oxidising agent with a primary alcohol
  • heated strongly under reflux with excess acidified potassium dichromate
  • produces a carboxylic acid and water
  • orange to green
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11
Q

How can you get a ketone through oxidation of an alcohol? State reagents and colour changes

A
  • react an oxidising agent with a secondary alcohol
  • heat under reflux with acidified potassium dichromate
  • will produce a ketone and water
  • orange to green
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12
Q

Explain esterification

A
  • reacting an alcohol with a carboxylic acid
  • this should be done in the presence sulfuric acid at a temp of 80 degrees C
  • reversible slow rate reaction
  • produces water and an ester, sweet smell
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13
Q

How do you name esters?

A
  • First part of the name is the chain that was once attached to the alcohol eg methyl
  • the second part of the name is the chain that was once attached to the carboxylic acid group (chain with the double bond o) eg methanoate
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14
Q

What is dehydration? Include necessary conditions and reagents

A
  • Type of elimination reaction
  • when alcohols are heated at 170 degrees c with concentrated sulfuric acid
  • produces an alkene and water
  • pi bonds form between adjacent carbons
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15
Q

How would you form a haloalkane from an alcohol?

A

Reagent would be hydrogen halide eg. HCl or HBr

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16
Q

What is a primary haloalkane?

A

Has the halogen at the end of a chain

17
Q

Why are halogens often delta negative in molecules?

A
  • Because it has a higher electro negativity than C or H

- polar bonds in haloalkanes

18
Q

What 2 factors affects the reactivity of haloalkanes?

A
  • Bond enthalpy, decrease down group; more reactive going down group 7 as bonding electrons are further from the nuclei
  • polarity of the C-X bond, fluorine is the most electronegative element so electronegativity decreases down the group
19
Q

What is neucleophilic substitution? Eg?

A

When an atom or group of atoms is exchange for a nucleophile - attracted to the partial positive charge on the carbon atom.
Hydrolysis: water or hydroxide ion solution

20
Q

Explain hydrolysis using aqueous alkali? What is the other form of hydrolysis?

A
  • When a haloalkane is heated under reflux with an aqueous solution containing hydroxide ions
  • produces an alcohol and a halide ion

Can be carried out with water, however the rate of reaction is slower

21
Q

What are chlorofluorocarbons?(CFCs)

A 
A class of organic compounds that contain chlorine and fluorine atoms
-As they are inert and non-toxic they are used as firefighting equipment/fire extinguishers/refrigerants
22
Q

What are CFC’s at room temp?

A

Gases

23
Q

What happens to CFC’s as they rise up into the stratosphere?

A

They become exposed to UV radiation:

  • This causes homolytic fission to occur
  • This creates 2 radicals, 1 is chlorine
24
Q

What is the effect of chlorine radicals from CFC’s at the ozone layer?

A

-Cl radical can compose ozone
-Cl radical reacts with ozone to form ClO radical and O2
ClO radical reacts with ozone to reform Cl radical and 2O2

25
Q

What other radicals react with the ozone?

A
  • In high temperatures or when lightning occurs nitrogen and oxygen can react to make nitrogen oxides
  • nitrogen monoxide can decompose ozone
26
Q

What is quickfit apparatus?

A

Heat-resistant glassware, joints must be greased sighting before use

27
Q

How do you conduct distillation?

A

Equipment:
•heating mantle
•thermometer
•thermometer holder
•condenser
•collecting flask
•round bottom flask
-Connect condenser to water supply and place hose with water going out into the sink
-pour organic mixture into round-bottomed flask with a few anti-bubbling granules to ensure smooth bubbling
-flask should be over a heating mantle to heat the mixture

28
Q

How can you heat under reflux? And why is this necessary?

A

Necessary to ensure that a reaction mixture does not boil away
•pear shaped flask
•heating mantle
•condenser

29
Q

How can you use a drying agent?

A

Inorganic salts such as magnesium sulfate and calcium chloride absorb water to become hydrated, they can act as drying agents for other chemicals

  • add a few spatulas of drying agent
  • if dying agent clumps, add more
  • when drying agent remains free-moving, organic product is dry
  • use gravity and filtration to collect filtrate which is the dry organic product
30
Q

What is redistillation?

A

Performing multiple distillations

Eg. To purify ethanol and water further

31
Q

How can you seperate immiscible liquids?

A

Using a separating funnel:

  1. Mount funnel on clamp over a reaction vessel
  2. Remove stopper and close tap
  3. Pour mixture into funnel half way, wash out reaction vessel w/ water and add this mixture to the funnel put stopper back
  4. Take the funnel out the ring and invert it, open tap to equalise pressure. Turn tap closed and shake continue to equalise pressure until you no longer hear a whistle.
  5. Put the funnel back into the ring and give the mixture time to seperate into layers
  6. Remove the stopper, put a beaker under spout and open tap to collect water
  7. Using a clean dry beaker open the tap and collect organic product
  8. Use drying agent and place organic product into a container
32
Q

How can you test for a haloalkane?

A

Silver nitrate ethanol and water

  • white precipitate-chloro
  • cream precipitate-bromo
  • yellow precipitate-iodo
33
Q

How can you test for carbonyl?

A

Acidified potassium dichromate

  • ketone: no change
  • aldehyde: orange turns green

Fehlings solution

  • ketone: no change
  • aldehydes: dark red precipitate

Tollens reagent

  • ketone: no silver mirror
  • aldehyde: silver mirror
34
Q

How can you test for a carboxylic acid?

A

Universal indicator
-pH of a weak acid

Reactive metal
-effervescence(hydrogen)

Metal carbonate
-effervescence(CO2)

35
Q

How can you test for an alcohol?

A

Warm with equal volume of carboxylic acid and sulfuric acid

-sweet smell of ester

36
Q

What are two examples of compounds with more than one functional group?

A

Aspirin and Niacin

Chem Mod 4 (2 decks)

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