chirality and organic acids

what are chiral molecules

a molecule that is not superimposable with it’s mirror image

what is the condition of becoming a chiral atom

containing at least one asymmetrically-substituted sp3 carbon atom

what is a stereoisomer (spatial isomer)

a type of isomer where the molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in thr 3D orientation of these atoms in space

why are these two molecules not chiral

because the central atom doesn’t have four DIFFERENT groups attached to it

what is an enantiomer

optical isomer meaning two molecular entities that are mirror images pf each other but not super imposable

how do we calculate the number of stereoisomers

a molecule with N chiral centers can be represented by2^n stereoisomers

how do we calculate the number of enantiomeric pairs (enantiomers)2^{n-}

a molecule with n chiral centers will have 2^{n-1} enantiomers

what are diasteromers

it’s a type of stereomer. stereomers that are not mirror images of each other

do enantiomers and diastereomers have identical physical properties

enantiomers do diastereomers dont

what are the two types of enantiomers

dextrorotatory (d) and levorotatory (l)

how do dextrorotatory and levorotatory enantomers rotate light

dextrorotatory rotates the light clockwise

levorotatory rotates the light counter clockwise

a 50% mixture of the d and l enantiomers doesn’t rotate the plane of a polarized light

what is the difference between diastereomers and enantiomers

they are both stereomers but diastereomer is not the mirror image and enantiomer is the mirror image (enantiomers are non-superimposable mirror images of each other)

what are the two configurations of chiral centers

the D/L system and the R/S system

the d/l system representation

is this a d or l enantiomer

d-amino acid

what is the d/l system estanlished for

carbohydrates

how to do the r/s configuration

when is a molecule not chiral

when the carbon atom has two identical substituents

what is a molecule that isn’t chiral bur can become chiral with a chemical reaction called

prochiral carbon atom

when is an enantiomer s and when is it r

R when it’s numbered clockwise

S when it’s numbered counter clockwise

what is used for the synthesis of proteins

only L-amino acids

how many in 20 proteins have chiral centers

19 of them have at least one chiral center

how many chiral centers does a ribose have

3 or 4 chiral centers

what is a racemic mixture

50% mixture of d and l enantiomers

give an example of chirality used in medicine

talidomide: ipnotic to fight nausea

it is a racemic mixture of two enantiomers (R-talidomide and S enantiomer)

R is sedative and S is teratogenic but they interconvert due to keto-enol tautomerism

what is the common name of methanoic acid and ethnoic acid

methanoic acid: formic acid

ethanoic acid: acetic acid

what is the hybridization of carboxylic acids

sp2

name these

what do we get when we oxide an aldehyde

carboxylic acid

how does ethanol become ethanoic acid (acetic acid)

we oxidize ethanol to get acetaldehyde (ethanal) then oxidize it again to get ethanoic acid = we oxidized it twice

are carboxilic acids soluble in water

yes but it becomes less soluble as chain gets longer (>5 carbons)

how is an anhydride formed

when two molecules of acid undergo condensation amd lose a water molecule (can be symmetric if it’s two molecules of same acid or asymmetric)

why are anhydrides highly reactive with nucleophiles (including water)

to give two molecules of acid in a highly exergonic reaction

what do we replace in the carboxyl group with what to get an acyl chloride or an acid chloride

replacement of -OH in the carboxyl group with chlorine

acyl and alkyl group representation

alpha hydroxyacids table

what are dicarboxilix acids

organic molecules containing two -COOH groups

dicarboxilic acids to memorize their names and structures

what is an alpha ketoacid

a carboxylic acid that have a keto group directly attached to the COOH

what are the other names of alpha-ketopropionic acid and alpha-ketoglutaric acid

pyruvate and alpha-ketoglutarate

when we reduce the ketone group what do we get

hydroxyl

where in our body do we see the reducing of ketone group to hydroxyl as pyruvic acid turning into lactic acid

this reaction in the muscles is useful to oxidize back NADH to NAD+

what is the common name of 3-oxobutanoic acid or beta-ketobutanoic acid

acetoacetic acid

decarboxylation, loss of CO2 in acetoacetic acid

why is acetoacetic acid produced

it’s produced by the liver under starvation conditions to send lipid analogues that can cross the blood brain barrier to the brain

what is the product of condensation of an acid and an alcohol

an ester

why do we use heat for the condensation of alcohol and an acid

to remove h2o

multistep mechanism in ester synthesis

phosphate esters are used to:

naming esters

what happens in the hydrolysis of esters

-it’s the opposite of the synthesis from acid and alcohol and is catalyzed by acids or bases.

-scission of a bond via a water-mediated nucleophilic attack

-C-C bonds are hyrolyzed slowly if at all

-C-O bonds can be hydrolyzed

examples of esters in biology

tryacylglycerides, phospholipids and phosphorylated amino acids (serine, threonine, tyrosine)q

what is a thioester

product of condensation between an acid and a thiol (sulfur containing alcohol)

why is it important that sulfur is bigger in size than oxygen

because it’s easier to hydrolyse the thioester and it has a longer bond

what is a thioester used for

to activate carboxyl-containing compounds for reactions

why are thioesters better than esters transferring an acyl group

Thioesters transfer acyl groups better because they are less resonance-stabilized and have better leaving groups

among these two thioesters which one of them is more preferred and stable

on the first one the 2p orbitals of O and 3p orbitals of S don’t superimpose well to form a pi bond due to their different sizes thus the only resonance form one can draw for a thioester is one with a charge separation between O and S like the second one

which one is more reactive an ester or a thioester

thioester is more reactive because the carbonyl carbon has a larger partial positive charge thus more reactive in nucleophilic substitutions

which one is a better leaving group the thiol or or the alcohol group?

thiol is because the negative charge is delocalized over a larger volume

ester vs anhydride