Alkyl and aryl groups

When a hydrogen atom is removed from an alkane, this is an alkyl group. The symbol R is used to represent a general alkyl group (i.e. a methyl, ethyl, propyl, etc. group). 

Do not confuse Ph with pH (see Section 1.7) or with phenol (C6H5OH). 

When a hydrogen atom is removed from a benzene ring this gives a phenyl confuse Ph with pH 

It is useful to draw a benzene ring as alternating C=C and C—C bonds as this helps to keep track of electron movement in reaction mechanisms (Section 7.2) 

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Quantum (Section 13 1) The energy associated with a photon Quaternary ammonium salt (Section 22 1) Salt of the type R4N X The positively charged ion contains a nitrogen with a total of four organic substituents (any combination of alkyl and aryl groups)... 

Alkyl and aryl groups are cleaved by iodine, but Cp groups are not affected (285). 

The reactions of 3-unsubstituted iso.xazolium salts (123) with hydroxide, alkoxide, cyanide and azide ions have also been studied, and they can in general be rationalized in terms of the ketoketenimine intermediate (124). The results of these reactions are summarized below. The application of such reactions to 3-unsubstituted isoxazolium salts bearing substituents other than alkyl and aryl groups has received little attention, but 5-aminoisoxazolium salts have been studied (74CB13). 

In addition to the steric effects shown especially by alkyl and aryl groups, the field effect of strongly polar groups must also be considered. For example, 4-hydroxypyrid-2-one-6-carboxylic acid (22)... 

Although alkyl and aryl groups attached to heterocycles are still called nonfunctional substituents, in fact they do undergo a variety of reactions and do have important electronic and steric effects on the molecule as a whole. 

It has been shown that cross-coupling reactions constitute a very mild method to introduce different alkyl and aryl groups to the most active C-3 position of the pyrazinone ring [26]. The broadly functionahzed 2-azadiene system of the title compounds was studied in cycloaddition reactions with various electron-reach and electron-poor dienophiles to provide highly substituted heterocycles [24]. 

More recently, we have extended the use of the condensation polymerization method to include many other combinations of alkyl and aryl groups in both homopolymers as well as copolymers. Future systematic studies of these materials should provide valuable information on the structure/property relationships which are applicable to this class of polymers. 

The aqua ion is not easily reduced nor oxidized. It is the slowest reacting of the bivalent transition metal ions with e " k = 7.7 X 10 M s ) and the product Mn+q is very reactive. However Mn(CNR)5 (R = a variety of alkyl and aryl groups) is stable and the selfexchange in the Mn(l,ll) hexakis(isocyanide) system has been studied by Mn and H nmr line broadening. The effects of solvent, temperature, pressure and ligand have been thoroughly explored. 

Metal-Mediated 1,3-Substitution Introduction of Alkyl and Aryl Groups... 

Substitution of alkyl and aryl groups on the oxetane ring, on the other hand, increases the barrier of the puckering vibration. 2-Methyloxetane and 3-methyloxetane are non-planar, existing as mixtures of stable equatorial and axial conformers at room temperature (79JST(56)157>. 

The postulated hydroperoxide-molybdenum complex indicates that there should be a steric and an electronic effect by the alkyl and aryl groups of the hydroperoxide. The steric effect is important in the transition state. The electronic effect will influence the rate of complex formation and the epoxidation reaction. Some data (Table VII) were obtained for these effects, but a clear distinction or evaluation of their role cannot be made at this time. 

Thiophene sulfones show no aromatic character, they behave as dienes and also show reactions of compounds containing a C = C bond conjugated with an electron-withdrawing group. Thiophene sulfone itself is highly unstable, but alkyl and aryl groups and fused benzene rings increase the stability. 

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