Shared Flashcard Set

Details

Solvents
N/A
21
Organic Chemistry
Undergraduate 2
07/05/2012

Additional Organic Chemistry Flashcards

 


 

Cards

Term
Polar Protic Solvents
Definition
These reagents are all relatively Bronsted acidic (they contain one or more hydrogen atoms that can be lost as a proton in a transfer reaction with water).
Term
Water (H2O)
Definition
A highly polar substance, it stabilizes ionic intermediates.  Fairly nucleophilic.  A strong hydrogen-bond donor and acceptor, considered a Bronsted acid and incompatible with most carbanions.
Term
Methanol (MeOH), Ethanol (EtOH), Isopropanol (i-PrOH), and Tert-Butanol (t-BuOH)
Definition
Highly protic solvents.  Miscible in water, thus can be co-solvents with water.  Bronsted acids.  Primary and secondary alcohols are good nucleophiles.  In the presence of strong acids (HCl, HNO3), tertiary alcohols and some secondary alcohols may ionize forming a carbocation.
Term
Acetic Acid (AcOH, CH3CO2H)
Definition
Polar Protic Solvent.  Weak Bronsted acid.  Can provide a good polar environment to stabilize ionic reactive intermediates generated by stronger acids.  Somewhat nucleophilic, will attack strongly electrophilic atoms and cationic intermediates to form an acetate ester product.
Term
Polar Aprotic Solevnts
Definition
Highly polar, but do not behave as Bronsted acids towards water.  Frequently used for SN2 displacement ractions where they stabalize the charge-separation that occurs in the transition state.  Hydrogen-bond acceptors, but not hydrogen-bond donors.
Term
Acetone (CH3C(O)CH3)
Definition
Polar aprotic solvent.  A good solvent for medium-to-high polarity organic molecules and some hydrocarbons as well.  Often used for SN2 displacement reactionswhere a soluble salt is the source of the nuclephile, but the leaving group forms and insoluble salt.
Term
Dimethylsulfoxide (DMSO, CH3S(O)CH3)
Definition
Polar aprotic solvent.  Disolves most organics and most inorganic salts.  Good solvent for SN2 displacement.  Incompatible with very strong nuclephiles or bases.  Somewhat nucleophilic, if there is no better leaving group around, DMSO will displace good leaving groups.
Term

N,N-Dimethylformamide

(DMF, HC(O)N(CH3)2)

Definition
Behaves like DMSO, but is not significantly nucleophilic.
Term
Ethers (as Solvents)
Definition
Medium polarity solvents.  Dissolve organics but do not dissolve common salts.  Typically Grignard reactions, reactions of organolithium reagents or LDA, or reactions with a metallic cation reagent.  Lewis bases and not Bronsted acids.
Term
Diethyl Ether (Ether, Et2O, CH3CH2OCH2CH3)
Definition
Ether.  Disolves many organic materials, but is only slightly soluable in water.  A weak Bronsted base, and can be protonated by anhydrous HCl or H2SO4.  Fairly good Lewis base and can solvate some metallic reagents (although not ionic salts).
Term
Tetrahydrofuran (THF, [image], C4H8O)
Definition
Ether.  Dissolves almost any organic molecule and a large number of inorganic reagents.  Solvates Lewis acids.  Weak Bronsted bases, only protonated by very stron Bronsted acids.  Miscible in water.
Term
Chlorinated Solvents
Definition
Moderately polar.  Denser than water.  Not flammable.
Term
Dichloromethane (methylene chloride, CH2Cl2)
Definition
Chlorinated Solvent.  Immiscible with water.  Dissolves mid- to low-polarity organics very well.  Dissolves common inorganic Lewis acids.  Stable to weak and medium Bronsted bases, but incompatible with carbanions and strong organic bases.
Term
Chloroform (CHCl3)
Definition
Chlorinated Solvent.  Chloroform-d, its deuterated form, is the most widely used solvent for organic NMR spectrometry.  Cannot be exposed to bases even as strong as hydroxide since it is easily converted to dichlorocarbene by and α-elimination reaction.
Term
Hydrocarbon Solvents
Definition

Neither acidic or basic in either the Lewis or Bronsted sense.  Will only dissolve low polarity organics.

Common aliphatic solvents: pentene, hexanes, iso-octane, and decalin

Common aromatic solvents: benzene, toluene, and xylenes

Term
Amine Solvents
Definition
Bronsted and Lewis bases.  Reactions that generate protons are frequently performed in the presence of amine bases.
Term
Triethylamine (Et3N, (CH3CH2)3N)
Definition
Amine solvent.  Miscible with water and most organics.  Often used as a reagent or co-solvent.
Term
Pyridine (Pyr,[image], C5H5N)
Definition
Amine solvent.  Quite nucleophilic.  Very soluable in water.
Term
Ethyl Acetate (EtOAc, CH3CO2CH2CH3)
Definition
Frequently used in extractions and in chromatography.  More polar than ether but less polar than THF.  Only slightly soluable in water.
Term
Acetonitrile (Methyl cyanide, CH3CN)
Definition
Highly polar solvent.  A good hydrogen bond acceptor, but not a hydrogen bond donor.  The nitrogen is very weakly basic but can be quite nucleophilic.  Miscible with water.  Frequently used as a solvent for SN2 reactions.
Supporting users have an ad free experience!