Methyl groups as substituents

Both remaining CgHi4 isomers have two methyl groups as substituents on a four carbon chain Thus the parent chain is butane When the same substituent appears more than once use the multiplying prefixes di tri tetra and so on A separate locant is used for each substituent and the locants are separated from each other by commas and from the words by hyphens... 

Fig. 3. Variation of heats of protonation in the gas phase of bases with N, 0, P, and S donor atoms as hydrogens are replaced by methyl groups as substituents on the donor atoms. Data from Ref. (12).

Now consider all the isomers that have two methyl groups as substituents on a five-carbon continuous chain. 

Give the structure and lUPAC name for each of the nine isomers having molecular formula C9H20 that contains seven carbons in the longest chain and two methyl groups as substituents. 

Draw the three constitutional isomers having molecular formula C7H14 that contain a five-membered ring and two methyl groups as substituents. For each constitutional isomer that can have cis and trans isomers, draw the two stereoisomers. 

Draw all possible constitutional and stereoisomers for a compound of molecular formula CeHi2 having a cyclobutane ring and two methyl groups as substituents. Label each compound as chiral or achiral. 

These results suggest that the stabilising effect of substituent groups is in the order Me,N>>MeO MeS F>H>Cl [41]. Both phenyl and methyl groups as substituents also appear to stabilise tropylium ions [42]. 

The effect of methyl groups as substituents in tetrahydroindenyltitanium compounds is shown in Figure 2.3. The catalytic activities and the stabilities of the compounds are changed by the substituents. 

Dithiin derivatives show a slightly poorer electron-acceptor ability than the oxathiin analogues, and the presence of methyl groups as substituents do not seem to alter significantly the reduction potential values (Table 1.13). 

---