Ochem 2 Lab Exam

theoretical study of interactions between matter and energy

spectroscopy

where is NMR found on the electromagnetic spectrum?

radio

what do different spectroscopies involve?

treating matter with different energies of light; this dictates the outcome of the interaction

what are the 4 different things to consider for NMR?

Number of signals, shift of signals, integration, and splitting of signals/multiplicity

number of signals

number of chemically unique environments within that structure

shift of signals

how upfield/downfield; determined by presence of electronegative atoms (closer to an EN atom, the further it goes)

integration

number of protons at that site

splitting of signals/multiplicity

number of peaks that correlate to our sites on that molecule (n + 1 rule)

the splitting of the proton atom by neighboring proton atoms

multiplicity

what are the 2 things used in Carbon NMR?

number of signals and shift of signals

what is deterated solvent used for?

to prevent oversaturation of solvent protons

refers to difference in resonance frequency of a nucleus compared to a reference standard compound

chemical shift

what makes a good reference standard?

stable, easily, identifiable, outside the typical spectral range, and (relatively) inert

what was commonly used in our labs and why?

Chloroform bc it has a single, sharp peak; also the fact that it is the solvent

where is chloroform found in NMR?

7.26 ppm

what is a common impurity and where is it found in NMR?

water at 1.54

interacts with molecules to produce vibrations (stretching/bending)

IR

IR has energy but...

not enough to do any electronic transition; cannot break a bond

What is IR characteristic of?

different bond types; functional groups

wavenumber is directly proportional to...

energy

the higher the wavenumber...

the stronger the bond

if a reaction is incomplete, then...

there will be both reactant and product present on the iR

what can water do on an IR?

can produce a false positive (OH peak) if used in a sample

what occurred in the spectroscopic analysis of a reaction lab?

pinacol to pinacolone; alcohol --> ketone

what occurred in borohydide reduction of camphor lab?

camphor to boreneol and isoboreneol; ketone --> OH

what occurred in the Iodination of salicymide lab?

di substituted benzene to tri substiuted benzene; aromatic sub. of iodine

what occurred in the synthesis of benzoic acid derivatives lab?

bromo benzene to benzoic acid; halo benzene --> COOH

what occurred in the preparation of aspirin lab?

salicylic acid to acetylsalycylic acid; hydroxy --> ester

what can R groups do to carbocations?

stabalize them; inductively, via hyperconjucation

what can also stabalize carbocations?

electron donating groups

carbocations can...

rearrange to form most stable intermediate

both sides are equivalent

symmetrical diols

group that migrates is the one that forms the more stable carbocation OR has higher migratory aptitude

asymmetrical diols

what is the order of strength for migratory apitude?

H- > phenyl > tertiary alkyl > secondary > primary > methyl

which intermediate was more stable in the spectroscopic analysis of a reaction lab?

the carbocation where the positive charge is located on the oxygen vs when it is on the carbon

what kind of rearrangement did we do in the spectroscopic analysis of a reaction lab?

acid mediated rearrangement, using 3M H2SO4

why did we purify our product using distillation?

because looking at the boiling points, pinacolone has a higher one than piniacol; this means we can boil it off and collect it

what drying agent was used in the spectroscopic analysis of a reaction lab?

anhydrous magnesium sulphate

loss of electron density on a carbon (loss of H or formation of C-O, C-N, C-X)

oxidation

gain of electron density on a carbon (gain of H or cleavage of C-O, C-N, C-X)

reduction

what reducing agent did we use in the borohydride reduction of camphor lab?

NaBH4

what happens when using NaBH4?

H- is added to carbonyl; mild (only reduces aldehydes and ketones)

whats another reducing agent?

LiAlH4; very powerful; indiscriminate reduction

what are borenol and isoborneol compared to one another?

epimers/diastereomers

which one is the major product?

isoborneol (exo product); pointing up

the Hydrogens are...

diastereotopic protons

what reaction was performed in the iodination of salicylamide?

electrophilic aromatic substitution

what are ortho/para directors that are activating?

Oh, NH2, OR, alkyl, aryl

what are ortho/para directors are...

electron donating groups

what are ortho/para directors that are deactivating?

F, Cl, Br, I; due to their EN

what are meta directors that are deactivating?

COH, COR, CO2H, CONHR, CN, NO2

what are meta directors are...

electron with drawing groups

how did we know which one was our major product in the iodination of salicylamide lab?

Because the 1,2,4-trisub showed up on the IR (in the fingerprint region)

what solvent was used in the iodination of salicylamide lab?

DMSO at 39.52 (multiiplet)

what happens during the formation of the grignard?

polarity inversion

a grignard is...

nucleophilic but also basic

what does it mean if the grignard is basic?

it has the opportunity to abstract the proton (in the solvent, moisture, etc.)

what did we ensure to do doing the lab so the grignard didnt take up any protons?

made sure glassware was dry

what does CO2 form through a grignard?

COOH

what test did we do during the prep of aspirin lab?

the Ferric Chloride Test

what does the Ferric Chloride test tell us?

detects the presence of a phenol group

if a phenol group is present, what happens?

the solution turns purple

what should happen with our product, acetylsalicylic acid?

no color change should happen because there is not phenol group present

what did the Carbon 13 NMR show for the prep of aspirin lab?

reactant only had 7 unique carbons; so the product should show 9 unique carbons

addition of an enol/enolate to an aldehyde/ketone

aldol condensation

why couldn't we use IR in the aldol condensation lab? what did we use instead?

phenyl groups present in every molecule; highly conjugated.

We used UV spec

what region will compounds have absorbance?

in 400-700

how do we tell what color is absorbed/reflected?

whatever colored is reflected, the absorbed color will be the one directly across from it on the color wheel

what kind of carbonyl did we observe in the aldol condensation lab?

a alpha beta unsaturated carbonyl

natural product extracted from indigofera plants

indigo

what did we do in the indigo reaction?

we reduced it, then oxidized it back to indigo

what is azo dye characterized by?

functional groups that can form covalent bonds with textile substrates

what did you form during the azo dye reaction?

a diazonium salt; N-N triple bond

cotton

covalent bonds and polar hydroxy groups

Filament acetate

acetate esters (reduces strong binding sites)

polyacrylic

one repeated nitrile group per repeated unit

silk and wool

polymers made of amino acid repeating units (acid/basic side chains often charged)

Nylon

diamine and diCOOH units

Polyester

week polar groups and do not bind highlight polar dyes

Dipole-dipole

electrostatic interactions of positive and negative ends of molecules

hydrogen bonding

strong dipole dipole interactions between molecules that have H bonded to highly EN atoms

ionic

electrostatic between positive ions and negative ions

london dispersion

due to instaneous dipole moments in polar or nonpolar molecules as a result of short-lived fluctuations of electron distribution; temporary induced dipole in adjacent molecules (weak bonds)