Organic Chemistry

This type of molecular orbital exhibits nodal planes that contain the internuclear axis itself, a property that fundamentally weakens the bond compared to its sigma counterpart. These orbitals arise from the lateral, side-by-side overlap of p atomic orbitals that are oriented perpendicular to the bond axis, rather than end-on overlap. Their reduced orbital overlap means they are always the weaker component in any multiple bond, and their antibonding counterparts are among the first to break in photochemical reactions. Double bonds contain exactly one of these interactions alongside one sigma bond, while triple bonds contain two. s, name these molecular orbitals characterized by electron density concentrated above and below the internuclear axis, formed through sideways overlap of p orbitals.

Hint: Think of the Greek letter π — just like its shape, these orbitals spread out sideways above and below the bond axis rather than straight through it.

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This reaction proceeds through a cyclic osmate ester intermediate that locks facial selectivity before hydrolysis releases the product. Osmium tetroxide catalyzes its syn-selective variant, while Sharpless asymmetric conditions use AD-mix reagents to achieve enantioselectivity exceeding 99% ee. When peroxyacids are used instead, an epoxide intermediate forms first, and subsequent acid-catalyzed ring opening delivers the anti stereochemical outcome. The Upjohn modification replaced stoichiometric osmium with catalytic amounts co-oxidized by N-methylmorpholine N-oxide, making it far safer for laboratory use. The reaction converts an alkene into a vicinal diol by adding two hydroxyl groups across the double bond. , name this organic transformation that installs two adjacent hydroxyl groups on a carbon-carbon double bond.

Hint: Think di- for two, hydroxy- for OH groups, and -ation for a reaction — two OH groups added across a double bond.

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In biological systems, this reaction type is thermodynamically unfavorable and typically requires enzyme catalysis or ATP input to proceed. It is the mechanism responsible for peptide bond formation when amino acids are linked together during protein synthesis. In organic chemistry, it occurs between a carboxyl group and a hydroxyl group, producing a byproduct with the molecular formula H₂O. The hallmark of this reaction is the joining of two molecules through the elimination of a small molecule — most commonly water. , name this reaction type that links monomers into polymers by releasing water.

Hint: Think of water being 'squeezed out' as two molecules bond together — like condensation dripping off a cold glass.

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This organometallic compound uses a rhodium(I) center coordinated by three triphenylphosphine ligands and one chloride, giving it a square planar geometry first characterized in 1965. Its catalytic cycle proceeds through oxidative addition of dihydrogen to form a rhodium(III) intermediate, followed by alkene coordination and hydride migration. Unlike heterogeneous platinum or palladium systems, it operates under mild conditions in homogeneous solution, making it highly selective for terminal over internal alkenes. Asymmetric variants inspired by its mechanism, using chiral diphosphine ligands like BINAP or DIPAMP, achieved breakthroughs in pharmaceutical synthesis and earned a Nobel Prize in 2001. Named after the British chemist who pioneered its study and later won the Nobel Prize himself, identify this landmark homogeneous hydrogenation catalyst with the formula ClRh[P(C6H5)3]3.

Hint: Think of the British Nobel laureate whose name is on the rhodium-triphenylphosphine catalyst that revolutionized homogeneous hydrogenation.

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This reaction proceeds through an enolate anion intermediate generated under basic conditions, where the alpha-carbon acts as a nucleophile attacking an electrophilic carbonyl carbon. The resulting beta-hydroxy carbonyl compound, called an aldol adduct, can either be isolated or driven to lose water in an elimination step. The reaction can be run intramolecularly to forge rings or crossed between two different carbonyl partners to build molecular complexity. It is a foundational carbon-carbon bond-forming reaction in organic synthesis that produces alpha,beta-unsaturated carbonyl compounds from aldehydes or ketones. s, name this base-catalyzed condensation reaction whose name combines the words for aldehyde and alcohol.

Hint: ALDehyde plus alcOHol equals ALDOL — the reaction that builds C–C bonds by stitching two carbonyl partners together and then kicking out water.

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