20A.2

Question 1

When synthesizing an organic product in your steps you always need to include

Answer 1

the name of the reaction and the regent used and the conditions in us used in and intermediates formed

Question 2

what is the steps to sentisise ethyl propanoate from bromoethane

Answer 2

step 1; heating heating reflux with aq NaOH (hydrolysis) to form ethanol

step 2: esterification by heating ethanol with propanoic acid using an acid catalyst

Question 3

what is the spider diagram of all alcohols

Answer 3

page 264

Question 4

what are the four ways we can extend the carbon chain

Answer 4

1. reaction the halogenoalkane with a cyanide ion to form a nitrile with one more carbon atom compared with the halogenoalkane
2. the addition of hydrogen cyanide to a carbonyl group
3. the alkylation of benzene, which introduces an alkali group into the benzene ring
4. using Grignard reagents

Question 5

what are Grignard reagents

Answer 5

they are compounds made from organometallic compounds containing magnesium that is covalently bonded to both an alkali group and a halogen (preferably Br) and they are used to synthesise organic compounds

Question 6

how do we prepare Grignard reagents

Answer 6

by heating under reflux the chosen halogenoalkane with magnesium all in a solvent of dry ether, halogenoarenes are also used such as bromobenzene and amongst the halogenoalkanes bromoalkanes are used in preference

Question 7

what is the general equation for the formation of Grignard reagents

Answer 7

R-Br + Mg —–> R-Mg-Br

Question 8

why in the formation of Grignard reagent both the halogenoalkane and the Mg are made and used in a solvent of dry ether

Answer 8

because Mg can react with water

Question 9

what are the general reaction of Grignard reagents with carbon dioxide and the carbonyl compounds (aldehydes, ketones, methanal) and the product formed form them and the change in the carbon chain

Answer 9

Carbon dioxide:
CO2 + RMgBr —> RCOOH (carboxylic acid)
(increase in carbon chain)

Methanal:
CH2O + RMgBr —-> RCH2OH (primary alcohol)
(increase in carbon chain)

Aldehyde(R’CHO):
R’CHO + RMgBr —-> RR’CHOH (secondary alcohol)
(a branch of variable length on the existing carbon chain)

Ketone(R’COR”):
R’COR” + RMgBr —-> RR’R”COH (tertiary alcohol)
(a branch of variable length on the existing carbon chain)

Question 10

after Grignard reagents reaction with the second reagent (CO2 or a carbonyl group) what must we add to achieve the desired organic product

Answer 10

hydrolysis using dilute acid

Question 11

Why are Grignard reaction better than using cyanide and potassium cyanide to add a carbon atom to the molecule

Answer 11

because it is a lot safer

Question 12

what is the examples of using Grignard reagent

Answer 12

page 265

Question 13

what will happen to the inorganic products from Grignard reaction (Mg(OH)Br

Answer 13

they will react with the dilute acid

Question 14

how does functional groups influence the compounds it is in

Answer 14

1. it will make some compounds act as nucleophiles, while other will act as electrophiles
2. it will make some compounds susceptible to addition reactions and others to substitution reaction
3. it will make some compounds easily oxidized and other more easily reduced

Question 14

how do we show the influence that functional groups has by comparing 4-methylphenol and Phenylmethanol

Answer 14

both dissolve in water but 4-methylphenol would be a slightly acidic that is because the lone pair of electron on the Oxygen in the OH group are incorporated with the delocalized electrons of benzene which makes the OH bond much more polar (but not acidic enough has carboxylic acid so when NaHCO3 Is added no bubble form differentiating from Carboxylic acids) all of this while Phenylmethanol forms a neutral solution,

another thing is that even though both have OH since Phenylmethanol will only be considered to be a primary alcohol and go through esterification once heated with Carboxylic acid in the presence of concentrated sulfuric acid while 4-methylphenol wont, and also while The OH group of 4-methylphenol provides an increased in electron density but the OH in the Phenylmethanol doesn’t 4-methylphenol can react and decolourise the Bromide water but Phenylmethanol wont

Question 15

Why cant we use a reagent of potassium dichromate(VI) and dilute sulfuric acid to distinguish between 4-methylphenol and Phenylmethanol

Answer 15

even though the phenol are not easily oxidized and primary alcohol are, both compounds would show a colour change from orange to green and that is because the 4-methylphenol contains a CH3 group that can becomes oxidized even though phenol doesn’t (so be wary when choosing your reagents to distinguish between two compounds)

Question 16

it what way should we approach a multi-step syntheses question

Answer 16

1. by checking if the carbon chain length has increased or decreased
2. by looking at the final product and working back to the starting compound
3. by looking at the starting compound and thinking of the types of reactions it can undergo

Question 17

what are the steps required to plan a reaction scheme

Answer 17

1. begin by writing all the compounds that can be readily converted into the final compound
2. then look at the starting compound and see if it can be converted into the one of these compounds
   3.then you should be able to see a clear route to convert the starting compound to the final compound
3. add reagents and condition required for each step