Organic Concepts - Organic Chemistry

In this molecule, the carbon that is directly attached to the nitrogen and the nitrogen itself are sp2 hybridized. This means that, within this bond, there are three sp2 orbitals present and the lone pair on the nitrogen occupies one of them.

A conjugated molecule is one that has its atoms arranged in such a way that allows p orbitals to lie parallel to each other. This allows for electron delocalization, which ultimately provides increased stability for the molecule. To find conjugated atoms, look for alternating single and multiple bonds. The circled carbon atoms are the only ones that are conjugated in this molecule.

The unsaturation number is equal to the number of rings and pi bonds in a molecule. Here, there are 4 rings and 1 double bond, so the unsaturation number is 5. No formula is needed to calculate unsaturation number when a structural formula is given.

The molecule pictured above is known as an ether because it contains an oxygen atom within the sequence of a carbon chain. (An oxygen atom bonded to two carbons in a carbon chain).

Therefore the correct answer is ether. All other answer choices are carbonyls, meaning that they contain a carbon atom double bonded to an oxygen atom.

Grignard reagents are very strong bases, and therefore can be spoiled by protons. Grignard reagents are so basic in fact that any protic solvent will render them useless. Dimethyl ether is the only non-protic solvent, and is therefore the correct answer.

IV>III>I>II

The most acidic compound is option IV because it contains a carboxylic acid group which is the most acidic organic functional group. Phenols are weak acids. Alcohols in solution are slightly less acidic than water and therefore are slightly basic.

The molecule's longest carbon chain has 6 carbons (thus, "hex-"), and the lack of double bonds makes it an alkane (thus "hexane"). The longest chain is a ring structure (thus "cyclohexane"), and the one branching group is a carbon chain consisting of one carbon and no double bonds (a "methyl" group). Because there are no other functional groups on the molecule there is no need to put a number before the location of the methyl group (thus "methylcyclohexane").

The molecule's longest carbon chain has 5 carbons (thus, "pent"), and the lack of double bonds makes it an alkane (thus "pentane"). The one functional group is a bromine atom attached to carbon number 3 (whether read from left to right or right to left, the bromine is always on carbon number 3). Thus, the molecule is named "3-bromopentane."

A good nucleophile should not be bulky. If the nucleophile is bulky, the compound will not be able to reach the carbonyl carbon, where the reaction occurs. With increased steric hindrance due to a bulkier nucleophile, the reaction will run slowly, and the compound is not a good nucleophile. Good nucleophiles also want to give away electrons so that the reaction can occur. This means that conjugate bases make better nucleophiles than acids.

The side of the reaction that is favored will have the acid with the higher , because the reaction goes (strong acid + strong base weak acid + weak base).

Addition reactions involve breaking one pi bond (double bond) and forming two sigma bonds in the product.

E1 reactions occur in two steps, forming a carbocation intermediate, which is most stable if there is a protic solvent present. Furthermore, the use of a weak base favors E1.

E2 reactions occur in one step; thus no carbocation intermediate is formed, and an aprotic solvent is favored. E2 reactions are favored by strong bases and higher temperatures.

An elimination reaction occurs when there is a release of atoms in a given compound to produce two or more products. In the reaction given a hydrogen and chloride atom are eliminated from the original compound to form one 2-butene, potassium chloride and water molecule.

Heterolytic bond breaking occurs in polar compounds to form to products of opposite charges. In these types of reaction two electrons from the original bond stays with one fragment upon cleavage. In the reaction given, the bond between the hydrogen and chlorine atom is broken with the two electrons from the original bond staying with the chlorine atom. The resulting products are hydrogen ion and chloride ion.

Homolytic bond breaking occurs when a molecule breaks up to form two or more new products. In the reaction given, molecular chlorine forms two radicals in which one electron stays with each fragment formed.

All of the given answers reflect SN1 reactions, except the claim that SN1 reactions are favored by weak nucleophiles.

SN1 reactions occur in two steps and involve a carbocation intermediate. The product demonstrates inverted stereochemistry (no racemic mixture). Tertiary substrates are preferred in this mechanism because they provide stabilization of the carbocation.

SN2 reaction mechanisms are favored by methyl/primary substrates because of reduced steric hindrance. No carbocation is formed via an SN2 mechanism since the mechanism is concerted; thus a strong nuclephile is used.

Substitution reactions—regardless of the mechanism—involve breaking one sigma bond, and forming another sigma bond (to another group).

This reaction would use an SN1 mechanism because the leaving group, bromine, is on a tertiary carbon, which is a carbon attached to three other carbon atoms. The bulk of these methyl groups would make SN2 impossible, but it would make the carbocation produced by an SN1 reaction very stable. The methyl group would lead to hyperconjugation, which is a type of resonance that stabilizes transition states.