CHEM 2125 Quiz Questions

What is the formula for finding degree of unsaturation?

(2C + 2 - H + N - X)/2

How does a mass spectrophotometer separates ion?

m/z

What are the differences between a secondary amine, a teritiary amine, and a primary amine with examples?

Primary amines have an electron charge at 1 degree, secondary amines have an electron charge at 2 degrees, and tertiary amines have an electron charge at 3 degrees

EX: Aniline is a primary amine

N-methylaniline and 1-propanamine are secondary amines

Trimethylamine is a tertiary amine

What is a nucleophile and what is an electrophile?

A nucleophile is a species that is electron rich and is attracted to something that is electron deficient to donate a pair of electrons to. An electrophile is a species that is electron deficient, so it is attracted to an electron rich species.

What is a lachrymator? Give an Example

A compound that irritates the eyes.

EX. Allyl Bromide

What is an Organometallic Reagant?

A carbon atom bonded to a metal

Ex. Allylmagenesium Bromide

What should you do hen you spill nitric acid on your skin?

Wash ith cold water for at least 15 minutes and notify TA immediately

What is the purpose of recrystallization?

To check for purity and to identify compound

What is a qualitative test?

Descriptive data from an experiment based on an observation

How to find theoretical yield

Step 1: Write down the balanced equation

Step 2: Use stoichiometry to determine the amount of moles, mmoles, grams, or ml of each reactant.

Step 3: The reactant that has the least amount is the limiting reactant

Step 4: Use stoichiometry again for the limiting reactant and product to get theoretical yield

List out all the meta directors (all are deactivators)

NO2, NO, CN, CO2H, CHO, COR, S(O)R, S(O)2R, SO2H

List out all the o/p directors (all are activators except halogens)

OH, OR, OC(O)R, NH2, NHR, NRR', NHC(O)R, SH, SR, R

What are alpha hydrogens

the hydrogens attached to the alpha carbon

What is the role of NaOH in the aldol reaction

NaOH acts as a base, facilitating the reaction by deprotonating alpha-hydrogens of aldehydes or ketones

What is an activated methylene group?

exhibits enhanced acidity and reactivity due to resonance stabilization of the resulting carbanion. Increases electron density

What is a lactone? Give an example.

a cyclic ester with a carbonyl group persisting on the anomeric carbon.

Ex. 3-carbethoxycoumarin

What chemicals are to be avoided in benzoin condensation lab and why? Explain with reactions if applicable

Potassium Cyanide: Poison reagent and mixing with an acid will cause HCN gas form

Strong Acids: Like benzoic acid can cause oxidation of benzaldehyde interfering with reaction

Oxidizing agents: Like concentrated HNO2 can oxidize benzaldehyde that can interfere with reaction

What is the purpose of a reflux?

heat mixtures for extended periods of time without solvent loss to extract compounds or carry out reactions

What is the difference between an activating group and a deactivating group?

activating groups help to increase the electrondensity in the aromatic ring and deactivating groups reduce the electron density in the aromatic ring

What is the purpose of ammonium chloride in barbier reaction?

To activate zinc by removing its oxide coating and the ammonia coordinates and stabilizes the organozinc as it forms

What is an enophile?

An electron-rich 1,3 diene

Dienophile

an electron poor alkene

Alder Endo Rule

if a dienophile contains activating groups (group x) with pi bonds they will prefer an ENDO orientation in the transition state

Diers-Alder Reaction

a ring is formed by the interaction of four pi electrons of the alkene with two pi electrons of the alkene or alkyne

What are the sterochemical requirements of the Diers Alder Reaction

Diene must be in s-cis conformation.

Diene's C1 and C4 p orbitals must overlap with dienophile's p orbitals to form new sigma bonds.

Both sigma bonds are on same face of the diene: syn stereochemistry.

Why does Cyclopentadiene undergo diers alder?

its fixed s-cis conformation

What happens when a diene is sterically hindered?

the reaction slows down even though the conformation can be s-cis

True or False: S-trans dienes cannot undergo the Diels-Alder reaction

True

Benzalacetones

Dehydrated aldol products of benzaldehyde andacetone

True or False: Aldehydes are less electrophilic than ketones and react with enolates slower

False

Mixed Aldols

where two different carbonyl compounds are used simultaneously in the reaction

Enolate

-results from deprotonation of alpha-carbon

-stabilized by resonance with the carbonyl

carbanion left, enolate right

Enolizable

carbonyl has alpha hydrogens

Knoevenagel reaction

Condensation of carbonyl compounds with active methylene groups.

Coumarins

anticoagulants and coronary vasodilators like warfarin

Condensation Reaction

a chemical reaction in which two or more molecules combine to produce water or another simple molecule

True or False: Electron Withdrawing Groups on the aromatic ring increase reactivity.

True

Electrophillic Carbon Substitution

involves a carbon-based electrophile leading to the formation of a carbon-carbon bond

What is the purpose of H2SO4 in butylation?

acts as a catalyst and a dehydrating agent, facilitating the reaction and removing water from the reaction mixture. Speeds up the reaction

Hinsburg Test

Tests for 1, 2, 3 amines. 1 amine is clear solution that on addition of HCl forms precipitate. 2 form oil/suspension which does not react with HCl. 3 insoluble solid/ oil that reacts with HCl to form clear solution

Nitrous Acid Test

Tests primary amines for diazonium salt formation.

What happens if the alkyl is not an aromatic ring?

diazonium salt immediately loses nitrogen forming the carbocation.

What happens if thr alkyl is an aromatic ring?

corresponding diazonium salt is stable in solution at < 10 ˚C

Organolithiums and Grignards

Grignard reagents are formed from magnesium and alkyl halides, while organolithium reagents are formed from lithium and alkyl halides, with organolithium reagents generally being more reactive and sensitive to moisture and air (Pyrophoric)