C10 - Organic Reactions Flashcards
-Alkenes molecules contain a double bond between the carbon atoms .
-Because of the double nomd , alkanes all react in a SIMILAR WAY .
-Scientists call the odubel bond - THE ALKENE FUNCTIONAL GROUP .
Meaning of functional group
Part of the molecule that determeines how it reacts .
-All alkenes have the SAME functional group (carbon to carbon double bond )
-Scientists call molecules sucha s alkenes a homologous series .
-Members of a homologous seriees all have the SAME FUNCTIONAL GROUP .
-Each molecule in a homologous series has an EXTRA CARBON ATOM +TWO EXTRA HYDROGEN ATOMS .
Learn the reactions for alkenes and the conditions
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- Combustion of alkenes (burns )
-When we combust alakanes we porduce carbondioxide and water , this is also true when we combust alkenes .
-HOWEVER , combusting an alkenee also produces unburnt carbon particles . That is because of INCOMPLETE COMBUSTION , menaing alkenees burn in air with a smoky flame .
-Alkenes reaction with hydrogen
(Check sheet)
-Known as HYDROG
-conditions for this reaction - REQUIRES A TEMPERATURE OF 150 DEGREES AROUND
-We also need a NICKEL CATALST - to speed up the reaction . .
Hydrogenation reaction explained
-In this reaction , the two hydrogen atoms add across the double bond .
-The carbon to carbon double bond is converted iNTO A CABON TO CARBON singl ebond .
-In e.g - ethene has to be converted into the alkane ethane
-SO REACITNG AN ALKENE WITH HYDROGEN PRODUCES AN ALKENE .
Reaction of alkekens with water is called HYDRATION
(check sheet )
CONDITIONS OF RHYDRATION
-Water must bei nt he form of steam .
-The temperature must be aroudn 300 degrees .
-Pressure around 70 atmospheres .
-We can also use phosphoric acid as a catalyst to speed up the reaction .
The reactions is reversible …
-SO to increase the yield of ethnol , any unreacted ethene and steam are passed back through the ctalsst .
This reaction might appear as a REVERSIBLE REACTIOn , in the exam .
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-Reaction of alkenes with Halogesn , Chlorine , Bromine , and Iodine .
-Alkenes react quiet rapidlyw ith Halogens .
Reaction with Chorien (check book)
-The two chlorine aotms int he chlorine molecule have added acroos the double bond .
-The oduble carbon to carbon bond have now turned into a single carbon to carbon bond .
Bromine …
-Iodine …
Dibromoethane
-Diodoethane
Uses of alkenes
-fuels
-Solvents
-Alcholic drinks
The alchohols are a homologous series (same funcitonal group)
which is OH .
CH3OH strcutral FORMULA for methanol .
Need to know the name and strcuture for the first FOUR ALCHOLS
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STRUCTURE OF METHANOL
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STRUCTURE OF ETHANOL
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STRUCTURE OF PROPONAL
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STRUCUTRE OF bUGTANOL
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ONE way of making alcohol
-Hyddration of Ethene .
-LOOKA AT LAST SHEET FORMULA
Advanatage of using hydration of ethene to make alcohol
-Reaction produces a high yeld of ethanol .
Disadvanatage of using hydration of ethene to make alcohol .
-Reaction reqruies a high temperature in other words - A LOT OF ENERGY ,
-Ethene for thi reaction comes from CRUDE OIl , this is nonrenewable .
ANOTHER WAY of making
-Fermentatiion of suagr .
-CHECK REACTION ON SHEET .
-In fermentation we start wuth a sugar solution such as glucose and we mix thris with yeast .
-The yeast converts to the sugar solution to a solution of ethnaol . Carbondioxide gaas is also produced .
What are the conditions of fermentation ?
-The temperature should be around 30 degrees .
-The reaction must take place in anaerboic conditions (without oxygen ) .
Advanatage of fermentation to make alcohol ?
-The low temperature means that the reaction does not require a lot of energy .
-The sugar for this reaction comes from plants and therefore , is renewable .
Dsadvanatage of fermentation to make alcohol ?
-The product is an aqueous solution of ethanol . (Ethanol dissolved in water) .
-We need to PURIFY ehtanol by distillaiton and that requires energy .
Alcohols solubility in water
-Alchoks are soluble in water and form neutral solutions .
-As the numebr sof carbon atoms increases the SOLUBILTITY DECREASES .
1.Reaction with sodium
(check sheet)
-Int his reaction we see bubbles of hydorgen gas being produced .
-We also make the product sodium ethoxide .
(same reaction for methanol ,ethanol and propanol and butanol , first THREE letters of each alocohol and add ‘oxide’)
ReEACTION WITH oxidising agents
(check sheet )
- good example of an oxidising agent is ACIDIFIED POTASSIUM DICHROMATE .
-When alchools react with oxidising agents , they produce CARBOXYLIC ACID +WATER .
(same reaction with other four alchosl first four letters add ‘oic’ and acid’)
Reaction with combustion
-Alchols release energy when combusted .
-Combusitng a n alochol in air produces carbondioxide+water .
check sheet and also balancing equations
If we react an alcohol with an oxidising agent ?
-We produce a carboxylic acid .
Carboxlic acids
-are a homologous serious , they all have the same fucnitonal group -COOH
-Rather than drawing the individual atoms and bons , scientists rather use a structural formulas .
-Learn the Chemical formulas .
These acids will be from smallest to biggest
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Chemical and structural formula for methanoic aicd
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Chemical and structural formula for ethanoic acid
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Chemical and structural formula for propanoic acid
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Chemical and strucutral formual ofr butaanoic acid .
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Dissolving carboxylic acids in water
check sheet for equation
-In water , carboxylic acids are weak acids
-Ethanoic acid is ionising to produce the ehtanotate ionand H+
What type of reaction is dissolving carboxylic acids in water
-This is a reversible reaction ; ethanoate ion and H+ can resemble to form ethanoic acid .
Why are carboxylic acids known as WEAK ACIDS ?
-As the carboxlic aicds onl partially ionse in aqueous solutions , they are Weak acids .
–Meaning carboxlic acids have a HIGHER pH than a strong acid such as hydrochloric acid .
Carboxylic acids reactng with metal carbonate
check sheet for equation .
Carboxylic acids reactng with metal carbonate EXPLAINED
check sheet and online ofr the other two carboxlic acids
-Get begginign of acid and stick’ate’ to it .
-We have made the salt sodiume thnaote and carbondioxide gas +water /
(all carboxylic acids react like this with emtl carbonates .)
Reaction of carboxylic acids with alcohols .
-check sheet for equation and learn .
-When we react carboxylic acid with an alcohol , we make a molecule called an ester . WE ALSO MAKE WATER .
-eSTERS ARE REALLY useful molecules , as they often have a plesant smell (used in perfumes) .
Key points about the reaction
-The reaction requires a sulfuric acid catalyst .
-It is a reversile reaction , so you can seeit in a quetion for reversible reactions .
