Alkyls neopentyl compounds

Archibald and Manser prepared NF2-substituted analogs of pentaerythrityl esters (such as PETN). Specifically, 3-(difluoraminomethyl)-3-methyloxetane (14) and 3,3-bis(difluoraminomethyl)oxetane (15) [101] were subjected to ring-opening nitration by nitric acid (Scheme 12), giving corresponding 1,3-propanediyl dinitrate esters in quantitative yield [105,106]. As neopentyl difluoramines, the products had superior stabihty compared to many other mono(difluoramino)alkyl-substituted compounds. 2,2-Bis(difluoraminome-thyl)-l,3-propanediyl dinitrate (16) showed a melting point of 58 °C and DSC onset/peak of 177/188 °C. 

It occasionally happens that a reaction proceeds much faster or much slower than expected on the basis of electrical effects alone. In these cases, it can often be shown that steric effects are influencing the rate. For example, Table 9.2 lists relative rates for the Sn2 ethanolysis of certain alkyl halides (see p. 390). All these compounds are primary bromides the branching is on the second carbon, so that field-effect differences should be small. As Table 9.2 shows, the rate decreases with increasing P branching and reaches a very low value for neopentyl bromide. This reaction is known to involve an attack by the nucleophile from a position opposite to that of the bromine (see p. 390). The great decrease in rate can be attributed to steric hindrance, a sheer physical blockage to the attack of the nucleophile. Another example of steric hindrance is found in 2,6-disubstituted benzoic acids, which are difficult to esterify no matter what the resonance or field effects of the groups in the 2 or the 6 position. Similarly, once 2,6-disubstituted benzoic acids are esterified, the esters are difficult to hydrolyze. 

The reactions were between the alkyl bronude and OEt . The rate for isopropyl bromide was actually greater than that for ethyl bromide, if the temperature differenee is eonsidered. Neopentyl bromide, the next compound in the P-branching series, cannot be compared because it has no p-hydrogen and cannot give an elimination product without rearrangement. 

A prerequisite for the a-elimination is the absence of (3-hydrogen atoms in the alkyl groups and this was successfully achieved by using the neopentyl substituents at the metal centre. The nature of the double bond between the metal and carbon was established by its bond length and the occurrence of stereoisomers [13], Typical feature of the Schrock carbenes is that they contain an electrophilic, high-valent metal atom and an electron rich carbene carbon atom. The reverse is true for the older, Fischer carbene compounds, such as the one mentioned, (OC)5W=CPh2. 

ControUed-potential oxidations of a number of primary, secondary, and tertiary alkyl bromides at platinum electrodes in acetonitrile have been investigated [10]. For compounds such as 2-bromopropane, 2-bromobutane, tert-butyl bromide, and neopentyl bromide, a single Ai-alkylacetamide is produced. On the other hand, for 1-bromobutane, 1-bromopentane, 1-bromohexane, 1-bromo-3-methylbutane, and 3-bromohexane, a mixture of amides arises. It was proposed that one electron is removed from each molecule of starting material and that the resulting cation radical (RBr+ ) decomposes to yield a carbocation (R" "). Once formed, the carbocation can react (either directly or after rearrangement) with acetonitrile eventually to form an Al-alkylacetamide, as described above for alkyl iodides. In later work, Becker [11] studied the oxidation of 1-bromoalkanes ranging from methyl to heptyl bromide. He observed that, as the carbon-chain length is increased, the coulombic yield of amides decreases as the number of different amides increases. 

R. P. Tooze, M. Motevalli, M. B. Hursthouse, and G. Wilkinson, Alkyl Compounds of Diruthenium(III) and Diosmium(III). X-Ray Crystal Structure of the First Ruthenium Peralkyl, Hexakis(neopentyl)diruthenium(III), J. Chem. Soc., Chem. Comm. 1984,799-800. 

Palladium-catalysed cross-coupling of organomagnesium compounds with alkyl halides is rarely useful (e.g. see [36]), but a satisfactory nickel-catalysed coupling with a neopentyl halide has been reported recently [37] ... 

In this class of compounds the nature of the alkyl group appears to determine the polarizability of the alkoxy group. The volatility of the compounds depends on the alkyl group. Groups such as neopentyl, f-butyl and triphenyl carbinol cause covalency in the metal alkoxides and hence to their volatility. 

Bis(pentametiiylcyclopentadienyl)actinide(IV) mono- and dialkyl complexes are readily prepared from Cp 2 Cl2. A rather large number of alkyl groups have been employed, and compounds of this class are generally prepared by metathesis (equation 59). In the solid state, complexes of formula Cp 2" n 2 adopt a pseudotetrahedral coordination geometry about the actinide metal. A neutron diffraction study of the thorium neopentyl complex Cp 2Th(CH2-t-Bu)2 also revealed agostic Th-H-C interactions with the q -CH bonds. ... 

Pure alkyl transition metal complexes are rare, owing to the -Elimination decay mechanism. An effective strategy to prepare such compounds must therefore aim at blocking possible decomposition pathways. Neopentyl is void of hydrogen in the jS-position, and neopentyl... 

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