Search results
Results From The WOW.Com Content Network
In organic chemistry, an allyl group is a substituent with the structural formula −CH 2 −HC=CH 2. It consists of a methylene bridge ( −CH 2 − ) attached to a vinyl group ( −CH=CH 2 ). [ 1 ] [ 2 ] The name is derived from the scientific name for garlic , Allium sativum .
There are five main types of acyl derivatives. Acid halides are the most reactive towards nucleophiles, followed by anhydrides, esters, and amides. Carboxylate ions are essentially unreactive towards nucleophilic substitution, since they possess no leaving group.
The silicon plays the key role in stabilizing the carbocation of carbon at the β-position. Hosomi-Sakurai reaction is also applicable for other functional groups such as enones, where conjugate addition is usually seen. In figure 2, the Hosomi- Sakurai reaction has been shown using a cinnamoyl ketone.
A solution of a carbonyl compound is added to a Grignard reagent. (See gallery) An example of a Grignard reaction (R 2 or R 3 could be hydrogen). The Grignard reaction (French:) is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides (Grignard reagent) are added to the carbonyl groups of either an aldehyde or ...
A widely accepted mechanism involves a carbocation intermediate. The Fries rearrangement. In the first reaction step a Lewis acid for instance aluminium chloride AlCl 3 co-ordinates to the carbonyl oxygen atom of the acyl group. This oxygen atom is more electron rich than the phenolic oxygen atom and is the preferred Lewis base.
The 2-norbornyl cation is one of the best characterized carbonium ion. It is the prototype for non-classical ions. As indicated first by low-temperature NMR spectroscopy and confirmed by X-ray crystallography, [1] it has a symmetric structure with an RCH 2 + group bonded to an alkene group, stabilized by a bicyclic structure.
Usually, alkyl groups are attached to other atoms or groups of atoms. Free alkyls occur as neutral radicals, as anions, or as cations. The cations are called carbocations. The anions are called carbanions. The neutral alkyl free radicals have no special name. Such species are usually encountered only as transient intermediates.
Beet sugar [1] – made from sugar beets, contains a high concentration of sucrose; Birch syrup – around 42-54% fructose, 45% glucose, plus a small amount of sucrose; Brown sugar [1] – Consists of a minimum 88% sucrose and invert sugar. Commercial brown sugar contains from 4.5% molasses (light brown sugar) to 6.5% molasses (dark brown sugar ...