Chemical Bonding and Molecular Structure

Tetra-n-butylammonium fluoride or TBAF is a quaternary ammonium salt .It is usually encountered in the latter form as a source of organic-soluble fluoride ion to remove silyl ether protecting groups. It is also used as a phase transfer catalyst and as a mild base.

Ishikawa's reagent is a fluorinating reagent used in organic chemistry. It is used to convert alcohols into alkyl fluorides and carboxylic acids into acyl fluorides. Aldehydes and ketones do not react with it.

Hexamethylenetetramine is a heterocyclic organic compound. This white crystalline compound is highly soluble in water and polar organic solvents. It has a cage-like structure similar to adamantane. It is useful in the synthesis of other chemical compounds, e.g. plastics, pharmaceuticals, rubber additives etc.

Methylmagnesium chloride is a commercially available Grignard reagent. Like methyllithium, it is the synthetic equivalent to the methyl carbanion synthon. It is usually sold as a solution in tetrahydrofuran. Two molecules of tetrahydrofuran (in the upper part of the drawing) coordinate by their oxygen atoms to magnesium.

Carboxybenzyl is an amine protecting group in organic synthesis. It is commonly used in peptide synthesis and is formed by reacting an amine with benzyl chloroformate and a weak base. It is used to protect amines from electrophiles.

This option is correct because isooctane has highest octane number and n-hexadecane has highest cetane number.

Organomagnesium compounds are widespread. They are commonly found as Grignard reagents. The formation of alkyl or aryl magnesium halides (RMgX) from magnesium metal and an alkyl halide is attributed to a SET process. Examples of Grignards are phenylmagnesium bromide and ethylmagnesium bromide.

This option is correct because according to bent rule more electronegative substituents prefer hybrid orbitals having less s-character and more electropositive substituents prefer hybrid orbitals having more s-character. An example of this rule is fluoromethanes.

This option is correct, because all the carbon atoms in but-2-ene lie in one plane and only carbon atoms of the double bond are sp²-hybridized.

The cyanate ion is an anion with the chemical formula written as [OCN]⁻ or [NCO]⁻. In aqueous solution,  it acts as a base, forming isocyanic acid, HNCO. The cyanate ion is an ambidentate ligand, forming complexes with a metal ion in which either the nitrogen or oxygen atom may be the electron-pair donor. It can also act as a bridging ligand.

London dispersion forces is a type of force acting between atoms and molecules.The LDF is a weak intermolecular force arising from quantum induced instantaneous polarization multipoles in molecules. They can therefore act between molecules without permanent multipole moments.

A dipolar bond, also known as dative covalent bond or coordinate bond is a kind of 2-centre, 2-electron covalent bond in which the two electrons derive from the same atom. Typically, a dipolar bond is formed when a Lewis base donates a pair of electrons to a Lewis acid.

A quadruple bond is a type of chemical bond between two atoms involving eight electrons. This bond is an extension of the more familiar types double bonds and triple bonds. Stable quadruple bonds are most common among the middle members transition metal elements such as rhenium, tungsten, molybdenum and chromium. Typically the ligands that support quadruple bonds are π-donors, not π-acceptors.

Bent bonds, also known as banana bonds, are bonds in strained or otherwise sterically hindered molecules whose binding orbitals are forced into a banana-like form. Bent bonds are often more susceptible to reactions than ordinary bonds.

A symmetric hydrogen bond is a special type of hydrogen bond in which the proton is spaced exactly halfway between two identical atoms. The strength of the bond to each of those atoms is equal. It is an example of a 3-center 4-electron bond. This type of bond is much stronger than normal hydrogen bonds, in fact, its strength is comparable to a covalent bond.