Orgo Ch 4.15- 4.

What do we want to prevent or redard?

__ may decompose or polymerize by __. Even the cells in living systems are damaged by __, wihich can lead to aging, cancerous mutations, or cell death.

__ are often added to foods and chemicals to retard spoilage by radical chain reactions. CHain reactions depend on what?

How can an inhibitor stop a chain?

Radical inhibitors also helpt to protect the __.

Like BHA, which is added to foods as an antioxidant to stop __ by reacting with radical intermediates for form a relatively stable __, vitamin E is a __ and is thought to react with radicals by losing the __ hydrogen atom.

__ are short lived species that are never present in high concentrations because they react as quikcly as they are formed

In most cases, __ are fragments of molecules (lie free radicals), often having atoms with unusual number s of bonds. Some of hte common __ contain carbon atoms with only two or three bonds, compared with C's four bonds in stable compounds. Such species react quickly with a variety of compounsd to give more stable products with __.

Although __ are nto stable compounds, tehy are important to our study of orgo. Most __ involve __.

Species with __ are classified according to their __, which depends on the number of __.

The __ have no nonbonding electrons and are positively charged. The __ have one nonbonding electron and are neutral. The __ have a pair of nonbonding electrons and are negatively charged.

The most common intermediates with a __ are the __, which has two nonbonding electrons on the divalent carbon atom, making it uncharged.

A __ is a species that contains a carbon atom bearing a positive charge. The positively charged carbon atom is bonded to three other atoms, and it has no __, so it has only __ electrons in  its valence shell. It is __, with a __ and bond angles of about __.

With only six electrons in the positive carbon's valence shell, a __ is a powerful __ and it may react with any __ it encounters. Like other strong acids, __ are unlikely to be found in basic solutions. __ are proposed as __ in many types of organic reactions.

Like free radicals, carbocations are __ species: They have fewer than eight electrons in the valence shell.

Also, like free radicals, carbocations are stabilized by __. Any __ stabilizes an electron-deficient carbocation in two ways. What are they?

This __ is a donation of electron density through the __ of the molecule. The positively charged carbon atom withdraws some __ from the __ bonded to it.

__ also have filled __ that can overlap with the empty p orbital on the positively charged carbon atom, further stabilizing teh __. Even though the attached __ rotates, one of its __ is always aligned with the empty p orbital, stabilizing teh __ carbon atom. This type of overlap between a p orbital and a sigma bond is called __.

In general, more highly substituted carboocations are what?

Unsaturated carbocations are also stabilized by __. if a pi bond is adjacent to a carbocation, what will happen?

What is the result?
__ is particulraly effective in stabilizing carbocations.

Carbocations are common __ in organic reactions. Highly substituted __ can ionize when they are heated in a polar solvent. The strongly __ reacts wtih any available __, often the solvent.

Carbocations are also strong __.

Like carbocations, free radicals are __ and __. Unlike carbocations, however, the p orbital perpendicular to the plane of the CH bonds of the radical is not __; it contains __.

Both radicals and carbocations are __ because they __ around the carbon atom. Like carbocations, radicals are stabilized by the electron-donating effect of __, making more highly substituted radicals more stable.

LEss energy is required to break a __ bond to form a more __.

Like carbocations, radicals can be stabilzized by __. Overlap with the p orbitals of a pi bond allows the __ to be __ over two carbon atoms. __ is particularly effective in stabilizing a radical.

A carbanion has a __ that bears a - charge. There are eight electrions around the carbon atom (three bonds and one lone pair), so it is not __; rather, it is __ and a strong __. A carbanion has the same electronic structure as an __.

The hybridization and bond angles of a simple carbanion also resemble those of an __. The carbon atom is __ and __. One fo the __ is occupied by an __.

Like __, carbanions are __ and __. A carbanion has a negatve charge on its carbon atom, however, making it a powerful __ and a stronger __ than an __>

Like other strong bases, carbanions are unlikely to be found in __. The stability order of carbanions reflects their __. __ and other __ slightly destabilize a carbanion. The order of stability is usually what?

Carbanions that occur as __ in organic reactions are almost always stabilized by neightboring groups. They can be stabilized by either __ or __.

__ also plays a role in stabilizing carbanions.

__ are the most common type of carbanions we will encounter in orgo rxs.

__ are uncharged reactive intermediates containing a __.

The simplest has the formula __ and is called __, just as a -CH2-- group in a molecule is a __.

One way of generating carbenes is to what?

A carbene has both a __ and an __, so it can react as a __ or as an __.

The most common sythetic reaction of carbenes is their __.

No simple carbenes have ever been purified or even made in a hiigh concentration. Why?

__ and __ are useful both the __ of other compounds and for investigation of __. The __ is generated in the presence of its target compound, so that it can react immediately, and the concentration of the carbene is always low.