C10 Organic reactions Flashcards
what is the functional group of alkenes?
the double covalent bond between two carbon atoms
what is the general formula for alkenes?
CnH2n
why is there no methene?
there has to be two carbon atoms for the carbon-carbon double bond
what does ‘functional group’ mean?
the part of the molecule which determines how it reacts
what is a homologous series?
a group of molecules which all have the same functional group and react in a similar way
what is produced during the combustion of alkenes?
carbon dioxide, water and unburnt carbon particles due to incomplete combustion
what does it look like when alkenes burn in air?
they burn with a smoky flame
what is hydrogenation?
when an alkene reacts with hydrogen
what are the conditions for the hydrogenation of alkenes?
150 degrees C, nickel catalyst
what happens during the hydrogenation of alkenes?
the hydrogen atoms add across the double bond to form an alkane
what is the reaction of water and an alkene called?
hydration
what happens during hydration of alkenes?
an alcohol is produced
what are the conditions for the hydration of alkenes?
water must be steam
temperature must be around 300 degrees C
pressure must be 70 atmospheres
phosphoric acid is used as a catalyst
what is a key fact about the hydration of alkenes?
the reaction is reversible
how is the yield of an alcohol increased during the hydration of alkenes?
unreacted alkene and steam are passed back through the catalyst
what happens when alkenes react with halogens?
the two halogen atoms add across the double bond and the double c-c bond forms a single c-c bond
how is an alcohol formed?
remove an -H from an alkane
add an -OH to the alkane
what is the functional group of alcohols?
-OH
what are the first 4 alcohols?
methanol
ethanol
propanol
butanol
what is the functional group of carboxylic acids?
-COOH
how do you form an ester?
replace the H in the -COOH of a carboxylic acid and add a hydrocarbon (alkyl) group
what is the functional group of esters?
-COO-
what is fermentation?
the reaction in which the enzymes in yeast turn glucose into ethanol and carbon dioxide
what does the use of ethanol as a fuel show?
alcohols are flammable
how do alcohols burn?
with a ‘clean’ blue flame
what is produced in the combustion of alcohols?
carbon dioxide
water
how do alcohols react with sodium?
similar to water but less vigorous
effervescence (bubbling)
hydrogen gas is produced
how can alcohols be oxidised (not with combustion)?
using chemical oxidising agents
how can ethanol be oxidised to ethanoic acid?
chemical oxidising agents
microbes in the air
what are the reactions of carboxylic acids like?
typical of acids
(MASH, BASHCO2, CASHCO2 ect.)
why are carboxylic acids weak acids?
their molecules do not completely ionise when dissolved in water, most of the molecules stay as they are
what is the general formula for making esters?
carboxylic acid + alcohol –acid catalyst–> ester + water
what are the properties of esters?
distinctive smells (many are sweet and fruity)
volatile
what are esters used for?
perfumes and food flavourings
