New chemicals

The US-EPA s New Chemicals Program, located in the OPPT, was established to help manage the potential risk from chemicals new to the marketplace. The program is mandated by Section 5 of TSCA. 

Chemicals not on the TSCA Inventory are considered new chemicals and must go through a review process before they can be marketed. Certain genetically modified microorganisms also come under the definition of new chemicals. 

Anyone who plans to manufacture or import a new chemical substance for a nonexempt commercial purpose is required to provide US-EPA with notice before initiating the activity. This premanufacture notice, or PMN, must be submitted at least 90 days prior to the manufacture or import of the chemical. US-EPA can place restrictions up to and including a ban on production, to be placed on the use of a new chemical before it is entered into commerce (US-EPA 2003, 2006c). 

---

Studies of inelastic scattering are of considerable interest in heterogeneous catalysis. The degree to which molecules are scattered specularly gives information about their residence time on the surface. Often new chemical species appear, whose trajectory from the surface correlates to some degree with that of the incident beam of molecules. The study of such reactive scattering gives mechanistic information about surface reactions. 

In corrosion, adsorbates react directly with the substrate atoms to fomi new chemical species. The products may desorb from the surface (volatilization reaction) or may remain adsorbed in fonning a corrosion layer. Corrosion reactions have many industrial applications, such as dry etching of semiconductor surfaces. An example of a volatilization reaction is the etching of Si by fluorine [43]. In this case, fluorine reacts with the Si surface to fonn SiF gas. Note that the crystallinity of the remaining surface is also severely disrupted by this reaction. An example of corrosion layer fonnation is the oxidation of Fe metal to fonn mst. In this case, none of the products are volatile, but the crystallinity of the surface is dismpted as the bulk oxide fonns. Corrosion and etching reactions are discussed in more detail in section A3.10 and section C2.9. 

Clusters are intennediates bridging the properties of the atoms and the bulk. They can be viewed as novel molecules, but different from ordinary molecules, in that they can have various compositions and multiple shapes. Bare clusters are usually quite reactive and unstable against aggregation and have to be studied in vacuum or inert matrices. Interest in clusters comes from a wide range of fields. Clusters are used as models to investigate surface and bulk properties [2]. Since most catalysts are dispersed metal particles [3], isolated clusters provide ideal systems to understand catalytic mechanisms. The versatility of their shapes and compositions make clusters novel molecular systems to extend our concept of chemical bonding, stmcture and dynamics. Stable clusters or passivated clusters can be used as building blocks for new materials or new electronic devices [4] and this aspect has now led to a whole new direction of research into nanoparticles and quantum dots (see chapter C2.17). As the size of electronic devices approaches ever smaller dimensions [5], the new chemical and physical properties of clusters will be relevant to the future of the electronics industry. 

ITiis chapter does not introduce new chemical reactions. On the contrary, mainly elementary reactions are employed. The attempt is made here to provide an introduction into the planning of syntheses of simple "target molecules" based upon the synthon approach ofE.J. Corey (1967A, 1971) and the knowledge of the market of "fine chemicals". 

To redefine an atom type associated with a force field, adjust the rules in the chem.rul file to represent the new chemical environment for a particular type and then compile the new types. It is always desirable to save the original chem. rul under another name prior to modifying chem.rul. Having modified chem.rul, you can... 

Many industrial processes involve a chemical reaction between two Hquid phases, for example nitration (qv), sulfonation (see Sulfonation and sulfation), alkylation (qv), and saponification. These processes are not always considered to be extractions because the main objective is a new chemical product, rather than separation (30). However these processes have many features in common with extraction, for example the need to maintain a high interfacial area with the aid of agitation and the importance of efficient phase separation after the reaction is completed. 

The tria2ine family of herbicides appeared in and after 1955, and the bipyridiniums in 1960. In 1967, two new chemical herbicides (1) were registered under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The number of new registrations swelled to 11 in 1975 and subsequendy dropped to three in 1990 and two in 1991. 

The pricing of a new chemical that will compete against other chemicals does involve the usual cost elements that set the price. However, it has been shown that an empirical approach may be of value. One empirical approach is the exclusion chart (7,8) developed in 1979 and modified several times over the years. The chart indicates the approximate volume that existing chemicals used for the same function have achieved at their price. There are exceptions where the new chemical can command a higher price and achieve comparable volume because it possesses a unique property. 

Initial evaluations of chemicals produced for screening are performed by smelling them from paper blotters. However, more information is necessary given the time and expense required to commercialize a new chemical. No matter how pleasant or desirable a potential odorant appears to be, its performance must be studied and compared with available ingredients in experimental fragrances. A material may fail to Hve up to the promise of its initial odor evaluation for a number of reasons. It is not at all uncommon to have a chemical disappear in a formulation or skew the overall odor in an undesirable way. Some materials are found to be hard to work with in that their odors stick out and caimot be blended weU. Because perfumery is an individuaHstic art, it is important to have more than one perfumer work with a material of interest and to have it tried in several different fragrance types. Aroma chemicals must be stable in use if their desirable odor properties are to reach the consumer. Therefore, testing in functional product appHcations is an important part of the evaluation process. Other properties that can be important for new aroma chemicals are substantivity on skin and cloth, and the abiHty to mask certain malodors. 

In other efforts, over 100 firms in the United States and Europe have adopted a specific stmctured work process for product/process development, called product/process and cycle time excellence (PACE). In effect, PACE makes new product and new chemical process development a business-driven. 

The LD q for sodium bromide taken orally by rats is 3.5 g/kg body weight, and the TD q orally in rats is 720 mg/kg (8). RTECS Hsts data on reproductive effects in male and female rats. Sodium bromide is Hsted in the TSCA Inventory, the Canadian Domestic Substances Hst (DSL), the European Inventory of Existing Commercial Chemical Substances (EINECS), the Japanese Existing and New Chemical Substances (ENCS), and the Korean Existing Chemicals Hst (ECL). It is not regulated by the U.S. Department of Transportation. 

Plasmas can be used in CVD reactors to activate and partially decompose the precursor species and perhaps form new chemical species. This allows deposition at a temperature lower than thermal CVD. The process is called plasma-enhanced CVD (PECVD) (12). The plasmas are generated by direct-current, radio-frequency (r-f), or electron-cyclotron-resonance (ECR) techniques. Eigure 15 shows a parallel-plate CVD reactor that uses r-f power to generate the plasma. This type of PECVD reactor is in common use in the semiconductor industry to deposit siUcon nitride, Si N and glass (PSG) encapsulating layers a few micrometers-thick at deposition rates of 5—100 nm /min. 

A new chemical sensor based on surface transverse device has been developed (99) (see Sensors). It resembles a surface acoustic wave sensor with the addition of a metal grating between the tranducer and a different crystal orientation. This sensor operates at 250 mH2 and is ideally suited to measurements of surface-attached mass under fluid immersion. By immohi1i2ing atra2ine to the surface of the sensor device, the detection of atra2ine in the range of 0.06 ppb to 10 ppm was demonstrated. 

There are very sophisticated programs to search these databases. The databases are used by chemists to design new chemical compounds and by dmg companies to design new dmgs for a great variety of diseases. Of special interest is the design of dmgs that fit into the active sites of proteins. 

In contrast to prescription dmgs, OTC dmgs and cosmetics are not subject to preclearance in the United States. However, the rules covering OTC dmgs preclude introduction of untested dmgs or new combinations. A "new chemical entity" that appears suitable for OTC dmg use requires work-up via the new dmg appHcation (NDA) process. In contrast, the use of ingredients in cosmetics is essentially unrestricted and may include less well known substances. 

Registration of a new chemical substance in the United States and Japan requkes similar comprehensive sets of data, although there are some differences. Obtaining all the data for a full registration can be time-consuming and costiy. In 1989 it cost approximately 150,000 and took about a year to register a new substance in Europe. 

---