chem organic 17 Flashcards
(24 cards)
define a chiral (asymmetric) carbon
occurs in carbon compounds with 4 different groups of atoms attached to a carbon
what is a racemate/ racemic mixture?
a mixture containing a 50/50 mixture of the two isomers (enantiomers)
what is another test besides Fehling’s sol that can be used to test for presence of an aldehyde group? and state reagent, conditioms, reaction, observations
Tollen’s reagent
formed by mixing aqueous ammonia and silver nitrate. The active substance is the complex ion of [Ag(NH3)2]+
conditions: heat gently
reaction: with aldehydes, a silver mirror forms coating the inside of the test tube
KETONES RESULT IN NO CHANGE
reduction of carbonyls
reagent, conditons, type od reaction, role of reagent
example
reagents: LiAIH4 in dry ether
conditions: room temp and pressure
type of reaction: reduction
role of reagent: reducing agent
e.g: aldehydes —> primary alchohol ( propanal—> propan-1-ol)
ketones —-> secondary alcohols
(propanone —> propan-2-ol)
carbonyl —-> hydroxynitrile
reagent, conditions, mechanism
reagent: HCN in presence of KCN
conditions: room temp and pressure
mechanism: nucleophilic addition
(the extra KCN increases the conc of the CN- ion nucleophile needed for the first step of the mechanism)
carbonyl + iodine (Iodoform test)
what does this produce
in presence of….
reagents:
conditions
produces CHI3 (a yellow crystalline ppt with an antiseptic smell)
reagents: iodine and sodium hydroxide
conditions: warm very gently
which certain carbonyls does the iodoform test work for?
only carbonyls with a methyl group next to the C=O.
ethanal is the only aldehyde that reacts, more commonly is methyl ketones
reaction of aldehydes and ketones with 2,4-DNP
test for?
product?
test for a carbonyl group in a compound
product is an orange ppt
the melting point of the orange crystal product can be used to identify which carbonyl was used
nitrile —> carboxylic acid
(hydrolysis of nitriles)
reagent, conditions?
reagents: dilute HCl/ sulfuric acid
conditions: heat under reflux
carboxylic acid —> acyl chloride
reagent, conditions?
reagent: PCl5
conditions: room temp
also produces POCl3 + HCl along w the acyl chloride
e.g : CH3COOH + PCl5 —-> CH3COCl + POCl3 + HCl
how can esters be hydrolysed and split up
by either heating with an acid of sodium hydroxide
hydrolysis of ester with acid
products, reagents, conditions?
products: carboxylic acid and alcohol
reagents: dilute acid (HCl)
conditions: heat under reflux
reaction is reversible and does not give a good yield of products
hydrolysis of ester with sodium hydroxide
e.g, reagents, conditions?
e.g: methyl propanoate + NaOH —> sodium propanoate + methanol
reagents: dilute sodium hydroxide
conditions: heat under reflux
reaction is not reversible and goes to completion
acyl chlorine —> carboxylic acid
reagent, conditions
reagent: water
conditions: room temp
acyl chloride —> ester
reagent, conditions?
reagent: alcohol
conditions: room temp
acyl chloride —> primary amide
reagent, conditions?
reagent: ammonia
conditions: room temp
acyl chloride —> secondary amide
reagent, conditions
reagent: primary amide
conditions: room temp
carboxylic acid + alcohol =
ester + water
acyl chloride + alcohol =
ester + HCl
dicarboxylic acid + diol =
poly(ester) + water
diacyl dichloride + diol =
poly(ester) + HCl
how can polyesters be hydrolysed
by acid and alkali
polyester + HCl will be hydrolysed and split up into…
the OG dicarboxylic acid and diol
polyester + NaOH will be hydrolysed and split up into….
the diol and dicarboxylic acid salt
