Silicones nomenclature

Fortunately for silicon nomenclature, these rules were formulated and put into use before a lot of troublesome names were introduced. Thus, silicane for SiH4 was changed to silane, which has a host of derivatives. Disilicoethane became disilane, triethylsilicol became triethylsilanol, etc. The system of rules for the nomaiclature of organosilicon compounds is an excellent example of what can be accomplished if nomenclature problems in new or rapidly developing fields are studied and solved before bad practices become established. 

The nomenclature of boron compounds is now at about the same stage as was that of the silicon compounds when the silicon nomenclature was developed. An advisory committee of the Nomenclature Committee of the ACS Division of Organic Chemistry has been studying this problem (5) and expects to present a comprehensive report soon. 

General Electric silicone nomenclature M = Me3SiOj/2, D = Me2Si02/2, T = MeSi03 2>... 

The prefix sila- designates replacement of carbon by silicon in replacement nomenclature. Prefix names for radicals are formed analogously to those for the corresponding carbon-containing compounds. Thus silyl is used for SiH3—, silyene for —SiH2—, silylidyne for —SiH<, as well as trily, tetrayl, and so on for free valences(s) on ring structures. 

Before discussing the chemistry and technology of silicone polymers it is necessary to consider the methods of nomenclature of the silicon compounds relevant to this chapter. The terminology used will be that adopted by the International Union of Pure and Applied Chemistry. 

The stmcture used as the basis of the nomenclature is silane SiH4 corresponding to methane CH4. Silicon hydrides of the type SiH3(SiH2) SiH ... 

For convenience a shorthand nomenclature is frequently used in silicone literature where... 

It is generally considered in this notation that methyl groups are attached to silicon atoms. This nomenclature allows structures like trimethylsiloxy-endblocked-polydimethylsiloxane (TMS-eb-PDMS) to be simply represented as MD M (Scheme 2). 

There is a well-established, simple terminology to identify various siloxane structures, depending on the type of the substituents on silicon atoms. This is given in Table 1. Throughout the text we shall use this convenient nomenclature system. 

Concerning the nomenclature of higher-dimensionality silicon polymers such as networks, ladders, cages, and dendrimers, the variety of architectures possible is too great to treat concisely here, and the reader is directed to IUPAC sources.2... 

The nomenclature of oligosilsesquioxanes (as well as of their homo derivatives) has not been elaborated. These compounds are polyhedral oligocyclic systems of general formula (XiSiOi.5) with n = 2m (m 2), i.e., n = 4, 6, 8,10,12, etc. and X is the substituent at the silicon atom. In the simplest case, all the substituents Xj may be the same. On the basis of the existing lUPAC rules for naming polycyclic compounds, oligosilsesquioxanes may be termed in two ways ... 

Carbon is, of course, unique in the number of hydrides it forms, but the elements in the proximity of carbon in the Periodic Table have a similar, if more restricted, propensity to form hydrides. Silicon, germanium, boron and phosphorus are obvious examples. For hydrides of these elements, and especially for their organic derivatives, the methods of substitutive nomenclature can be applied to obtain suitable names. 

Nuclear Magnetic Resonance (NMR). This technique is essentially based on the same principle as ESR, but NMR is capable of detecting nuclei (MHz) instead of electrons (GHz). (Lack of a standardized nomenclature has resulted in numerous modifiers in connection with magnetic resonance instrumentation—electron, proton, nuclear, etc, plus apphcaaon-related terms, such as silicon-29, oxygen-17, nC S,P NMR, elc.)... 

Hydrolysis and condensation reactions of silanes may be considered in the broad category of nucleophilic substitutions at silicon. The common nomenclature for these reactions is SN.V-Si, where A represents the kinetic order or molecularity, Si indicates that silicon is the reaction center, and SN indicates that the reaction is a nucleophilic substitution. Nucleophilic reactions at silicon have been reviewed thoroughly and have been the subject of fundamental studies by several laboratories over the last three decades [33]. The literature is not as voluminous as the literature on the corresponding reactions at carbon. A general mechanistic view of these reactions has, however, emerged. There are many parallels to carbon-centered reaction mechanisms. One distinction from carbon-centered reactions is clearly apparent. Silicon is able to form relatively stable higher coordinated (pentavalent) intermediates carbon is not [33]. 

Another point which needs to be clarified from the start is the nomenclature of metalated silanes We will frequently use the term silyl anion in this chapter when we talk about metalated silanes. Although the term anion defines, literally taken, an ionic compound, this expression, when used by us, does not necessarily imply that the compound in question is of ionic nature, but covers, as well, in analogy to the use of the term carbanion , silicon compounds with a polarized covalent silicon-metal bond. 

The whiskers that are commonly added to silicon nitride to form composites are Si3N4 and SiC (common nomenclature is to add the suffix (w) to denote whiskers and this will be used where appropriate). Although other ceramic and metallic whiskers are available (e.g. BN, TaC, TiC, B4C and Fe), Si3N4 and SiC each have properties that make them prime candidates as reinforcements, not least of which is that they can sustain the high temperatures and reactivity of the sintering process without being degraded. 

See also Silicon tetrachloride) Silicon compounds, halomethyl derivatives by the diazomethane method, 6 37, 39 nomenclature of, 2 265 organo-, 3 50 nomenclature of, 3 55 Silicon tetraacetate, 4 45 Silicon tetrabromide, 1 38, 40 Silicon tetrachloride, 1 44 Silicon tetrafluoride, 4 145 Silicooxalic acid, (H Si, ,), formation of, by disilicon hexa-bromide, 2 101... 

Figure 3.12 Examples of building blocks of organic-inorganic hybrid materials along with their names according to a rational nomenclature system that is already applied in the field of silicone research.

TABLE 2. Nomenclature for the different silicon species depending on the level of condensation... 

A significant amount of information regarding the uses of silicone surfactants is still found primarily in the patent art, but the major applications have recently been reviewed in journals. Silicone (or siloxane) surfactants are also called silicone polyethers (SPEs), polyalkylene oxide silicone copolymers, silicone poly(oxyalkylene) copolymers and silicone glycols. The International Cosmetic Ingredient Nomenclature and the Cosmetic, Toiletry and Fragrance Association (CTFA) adopted name is dimethicone copolyol. 

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