C nucleophiles

cyanide as a nucleophile. equilibrium? name of products?

show mechanism for benzaldehyde

acts as a nucleophile in S_N2 reactions and for addition to aldehydes and ketones. equilibrium usually lies to the side of the product under acidic conditions. products are called cyanohydrins - reduction or hydrolysis of the nitrile group in these generates useful building blocks for pharmaceutical synthesis.

2 further reactions of cyanohydrins

functional groups created?

reagents/conditions

characterise reactant + product

reagents/conditions

characterise reactant + product

acetylide anions

organometallics as nucleophiles

• how do they react

• give example for acetylide anions

• HOMO?

• the reagent is not actually a free anion but instead has a polar carbon-metal bond (to Li for acetylide)

• remember that although R-M react as R^- the metal is still heavily involved in the reaction

mechanism of acetylide with this (need to know reaction not structures)

how are organometallics made

reaction of organic halides (usually Br or I) with the elemental metal (Li/Mg). they are air and moisture sensitive and must be used in dry, aprotic solvents like THF or Et₂O.

how are secondary alcohols synthesised

• reduction of ketones

• or addition of organometallics to aldehydes - if R₁ ≠ R₂ there are two possibilities for this

how are tertiary alcohols synthesised

addition of organometallics to ketones - if R₁ ≠ R₂ ≠ R₃ there are three possibilities

what are grignard reagents

organomagnesium halide reagents

R-MgBr with aldehyde (methanal)

which group in an organometallic is the nucleophile/base?

the organic group as the carbon has a partial negative charge due to the electropositivity of the metal