Chemistry
Naphthalene
Naphthalene is a white, crystalline compound with a strong, distinctive odor. It is composed of two fused benzene rings and is commonly used as a moth repellent and in the production of dyes, resins, and synthetic tanning agents. In chemistry, naphthalene is also studied for its aromatic properties and as a precursor in the synthesis of various organic compounds.
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7 Key excerpts on "Naphthalene"
eBook - PDF- Stanley E. Manahan(Author)
- 2009(Publication Date)
- CRC Press(Publisher)
Naphthalene is the simplest member of a large number of polycyclic aro-matic hydrocarbons having two or more fused rings. It is a volatile white crystalline matic hydrocarbons having two or more fused rings. It is a volatile white crystalline solid with a characteristic odor and has been used to make mothballs. The most solid with a characteristic odor and has been used to make mothballs. The most important of the many chemical derivatives made from Naphthalene is phthalic important of the many chemical derivatives made from Naphthalene is phthalic anhydride, from which phthalate ester plasticizers are synthesized. anhydride, from which phthalate ester plasticizers are synthesized. Polycyclic Aromatic Hydrocarbons Polycyclic Aromatic Hydrocarbons Benzo[ Benzo[ a ]pyrene (Figure 9.8) is one of the most widely studied of the polycyclic ]pyrene (Figure 9.8) is one of the most widely studied of the polycyclic aromatic hydrocarbons (PAHs), which are characterized by condensed ring systems aromatic hydrocarbons (PAHs), which are characterized by condensed ring systems (“chicken wire” structures). These compounds are formed by the incomplete com-(“chicken wire” structures). These compounds are formed by the incomplete com-bustion of other hydrocarbons, a process that consumes hydrogen in preference to bustion of other hydrocarbons, a process that consumes hydrogen in preference to carbon. The carbon residue is left in the thermodynamically favored condensed aro-carbon. The carbon residue is left in the thermodynamically favored condensed aro-matic ring system of the PAH compounds.
eBook - PDFOrganic Chemistry
Made Simple
- S. K. Murthy, S. S. Nathan(Authors)
- 2013(Publication Date)
- Made Simple(Publisher)
f S S // S S S S 1 ii n i n 1 i ii i 1 v y v //%/ %//%/ %//%/ A A A -A 0 0 0 0 Resonance between these structures results in the peculiar stability of the above free radical. Naphthalene (CioHg). Of the aromatic hydrocarbons containing con-densed ring systems and present in coal tar, Naphthalene is the most abundant. It is important as the starting material for the manufacture of phthalic anhydride and other intermediates for the dye industry. As a moth repellent, it has been supplanted by other more effective substi-tutes. Mono-substituted Naphthalene derivatives are referred to by the pre-fix a or ß and poly-substituted derivatives by numbers. (a)8 1(a) 5(a) 4(a) Naphthalene gives two mono-substituted products of the type C10H7X and ten di-substituted products of the type C10H6X2. REACTIONS: Air oxidation of Naphthalene in the vapour phase with vanadium pentoxide as catalyst is the basis for the manufacture of phthalic anhydride: J?/% [Ο], 500° C. -H a O < ^ / C ( J ' ' >l II H II o Phthalic acid Phthalic anhydride Naphthalene undergoes halogenation, nitration, and sulphonation in much the same manner as benzene (see later under the appropriate derivatives). In general, the a- or 1-position is more easily substituted than the ß- or 2-position. The double bonds in Naphthalene exhibit in part the reactivity of olefines. For example, Naphthalene adds on hydrogen more easily than benzene. This reduction can be ac-complished in stages to give di-, tetra-, and cfeca-hydroNaphthalenes respectively. Anthracene (Q4H10). This hydrocarbon is obtained from the anthra-cene oil fraction of coal-tar distillation. The synthesis of anthracene from 0-bromobenzyl bromide lends support to the structure of the com- Benzene and its Derivatives 199 pound as a condensed linear system of three benzene rings, as shown below: rv CH * + Y^fVY^i-suAVt / B r B r H 2 c / V V y / ' Υ Υ τ o-Bromobenzyl H H bromide Anthracene is considered to be a resonance hybrid of the following structures.
eBook - PDFIndustrial Arene Chemistry
Markets, Technologies, Sustainable Processes and Cases Studies of Aromatic Commodities, 4 Volume Set
- Jacques Mortier(Author)
- 2023(Publication Date)
- Wiley-VCH(Publisher)
The challenge associated with the industrial production of bi- and tri-nuclear aro- matic hydrocarbons as purified compounds is one of separation. These compounds are not purposefully produced from coal or petroleum. These aromatic compounds are present in the products from some petroleum refinery processes and in the coal tar from coal carbonization. In the case of coal, coal carbonization is the primary process, and coal tar is only a by-product [20]. Similarly, in the case of petroleum, refining to produce transport fuels is the primary process, and the recovery of aro- matics as a by-product is a secondary process. Although many of the bi- and tri-nuclear aromatics are separated and concen- trated with Naphthalene and anthracene, the extent to which the other aromatics are purified as individual compounds is more limited. Naphthalene is the starting material for a wide range of materials [21], including large capacity Naphthalene derivatives such as 1- and 2-hydroxyNaphthalene (α- and β-naphthol) with a global capacity of the order 10 5 t/a [22]. However, the primary use for Naphthalene is for the production of phthalic anhydride by oxidation [3], where it is in direct competition with ortho-xylene as feed material (see Chapters 36 and 37). Anthracene is mainly used as starting material for oxidation to anthraquinone [14], and the need and use of anthraquinone drives its market demand. Naphthalene is also a potential starting material for the production of anthraquinone [23], and in this respect anthracene is to some extent in competition with Naphthalene. 8.4 Naphthalene Prior to 1960, all Naphthalene was obtained from coal liquids [24]. The supply chal- lenge inherent in this situation was that Naphthalene was a by-product from coal carbonization (see Section 8.3), which created an inelastic supply situation. Many changes happened in the 1960s in an attempt to forestall a projected naph- thalene shortage.
eBook - PDF- John H. Montgomery(Author)
- 2007(Publication Date)
- CRC Press(Publisher)
774 Naphthalene Synonyms: AI3-00278; Albocarbon; BRN 1421310; Camphor tar; Caswell No. 587; CCRIS 1838; EINECS 202-049-5; EPA pesticide chemical code 055801; Mighty 150; Mighty RD1; Moth balls; Moth flakes; Naphthalin; Naphthaline; Naphthene; NCI-C52904; NSC 37565; RCRA waste number U165; Tar camphor; UN 1334; White tar. Note: Technical grades of Naphthalene may contain one or more of the following impurities: acenaphthene, benzo[ b ]thiophene, carbazole, chrysene, fluoranthene, fluorene, naphthacene, phenanthrene, pyrene, pyridine, and tetrazene. CASRN: 91-20-3; DOT: 1334 (crude/refined), 2304 (molten); DOT label: Flammable solid; molecular formula: C 10 H 8 ; FW: 128.18; RTECS: QJ0525000; Merck Index: 12 , 6457 Physical state, color, and odor: White, crystalline flakes, or powder with a strong aromatic odor resembling coal-tar or moth balls. At 40 ° C, the average odor threhold concentration and the lowest concentration at which an odor was detected were 6 and 2.5 μ g/L, respectively. Similarly, at 25 ° C, the average taste threshold concentration and the lowest concentration at which a taste was detected were 50 and 25 μ g/L, respectively (Young et al., 1996). A detection odor threshold concentration of 200 μ g/m 3 (38 ppb v ) was experimentally determined by Punter (1983). Melting point ( ° C): 80.5 (Weast, 1986) 80.28 (Fowler et al., 1968) Boiling point ( ° C): 217.942 (Wilhoit and Zwolinski, 1971) Density (g/cm 3 ): 0.9625 at 100 ° C (Weast, 1986) 1.145 at 20 ° C (Weiss, 1986) 1.01813 at 30 ° C, 0.9752 at 85 ° C (quoted, Standen, 1967) Diffusivity in water (x 10 -5 cm 2 /sec): 0.483 at 10 ° C, 0.749 at 25 ° C, 1.06 at 40 ° C (open tube elution method, Gustafson and Dickhut, 1994) Dissociation constant, pK a : >15 (Christensen et al., 1975) Flash point ( ° C): 79.5 (NIOSH, 1997) Lower explosive limit (%): 0.9 (NIOSH, 1997) Upper explosive limit (%): 5.9 (NIOSH, 1997)
eBook - ePubCreative Chemistry
Descriptive of Recent Achievements in the Chemical Industries
- Edwin E. (Edwin Emery) Slosson(Author)
- 2005(Publication Date)
- Perlego(Publisher)
When the tar is redistilled we get, among other things, the ten "crudes" which are fundamental material for making dyes. Their names are: benzene, toluene, xylene, phenol, cresol, Naphthalene, anthracene, methyl anthracene, phenanthrene and carbazol.There! I had to introduce you to the whole receiving line, but now that that ceremony is over we are at liberty to do as we do at a reception, meet our old friends, get acquainted with one or two more and turn our backs on the rest. Two of them, I am sure, you've met before, phenol, which is common carbolic acid, and Naphthalene, which we use for mothballs. But notice one thing in passing, that not one of them is a dye. They are all colorless liquids or white solids. Also they all have an indescribable odor—all odors that you don't know are indescribable—which gives them and their progeny, even when odorless, the name of "aromatic compounds."Fig. 8. Diagram of the products obtained from coal and some of their uses. Fig. 8. Diagram of the products obtained from coal and some of their uses.The most important of the ten because he is the father of the family is benzene, otherwise called benzol, but must not be confused with "benzine" spelled with an i which we used to burn and clean our clothes with. "Benzine" is a kind of gasoline, but benzene alias benzol has quite another constitution, although it looks and burns the same. Now the search for the constitution of benzene is one of the most exciting chapters in chemistry; also one of the most intricate chapters, but, in spite of that, I believe I can make the main point of it clear even to those who have never studied chemistry—provided they retain their childish liking for puzzles. It is really much like putting together the old six-block Chinese puzzle. The chemist can work better if he has a picture of what he is working with. Now his unit is the molecule, which is too small even to analyze with the microscope, no matter how high powered. So he makes up a sort of diagram of the molecule, and since he knows the number of atoms and that they are somehow attached to one another, he represents each atom by the first letter of its name and the points of attachment or bonds by straight lines connecting the atoms of the different elements. Now it is one of the rules of the game that all the bonds must be connected or hooked up with atoms at both ends, that there shall be no free hands reaching out into empty space. Carbon, for instance, has four bonds and hydrogen only one. They unite, therefore, in the proportion of one atom of carbon to four of hydrogen, or CH4 , which is methane or marsh gas and obviously the simplest of the hydrocarbons. But we have more complex hydrocarbons such as C6 H14
eBook - PDF- T. W. Graham Solomons, Craig B. Fryhle, Scott A. Snyder(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
A close look at one example, Naphthalene, will illustrate what we mean by this. According to resonance theory, a molecule of Naphthalene can be considered to be a hybrid of three Kekulé structures. One of these Kekulé structures, the most important one, is shown in Figure 14.15. There are two carbon atoms in Naphthalene (C4a and C8a) that are common to both rings. These two atoms are said to be at the points of ring fusion. They direct all of their bonds toward other carbon atoms and do not bear hydrogen atoms. 1 2 3 4 5 6 7 8 9 10 3 2 1 10 9 8 7 6 5 4 7 6 5 4 3 8 2 1 7 6 5 10 8 9 4 3 2 1 Naphthalene C 10 H 8 Anthracene C 14 H 10 Phenanthrene C 14 H 10 Pyrene C 16 H 10 Benzo[a]pyrene C 20 H 12 Dibenzo[a,l ]pyrene C 24 H 14 FIGURE 14.14 Benzenoid aromatic hydrocarbons. Some polycyclic aromatic hydrocarbons (PAHs), such as dibenzo[a,l]pyrene, are carcinogenic. (See “Important, but hidden, epoxides” at the end of Chapter 11.) 7 6 5 4 4a 8 1 2 3 8a C C C H C H C C H H H C H C H C C H or FIGURE 14.15 One Kekulé structure for Naphthalene. How many 13 C NMR signals would you expect for acenaphthylene? Acenaphthylene Strategy and Answer Acenaphthylene has a plane of symmetry which makes the five carbon atoms on the left (a–e, at right) equivalent to those on the right. Carbon atoms f and g are unique. Consequently, acenaphthylene should give seven 13 C NMR signals. SOLVED PROBLEM 14.4 Acenaphthylene a a b b c c d d e e f g 14.11 Other Aromatic Compounds 651 Molecular orbital calculations for Naphthalene begin with the model shown in Figure 14.16. The p orbitals overlap around the periphery of both rings and across the points of ring fusion. When molecular orbital calculations are carried out for Naphthalene using the model shown in Figure 14.16, the results of the calculations correlate well with our experimental knowledge of Naphthalene.
eBook - ePub- (Author)
- 2014(Publication Date)
- Wiley-VCH(Publisher)
14 ), which are important as synthetic tanning agents or as plasticizers for concrete. DinonylNaphthalene, prepared from Naphthalene and nonene, is sulfonated to give derivatives that are important as lubricating oil additives [13].3. Naphthols
Naphthols are the most important Naphthalene derivatives because they are key intermediates in the production of many chemicals other than dyes and pigments. World production is estimated at 40 000 t/a of 1-naphthol and 100 000 t/a of 2-naphthol.The production methods for naphthols are as follows (the first four methods are analogous to those for phenols):The last method is not applicable to phenols, for which the corresponding reaction requires two steps, diazotization of the aminobenzene followed by hydrolysis.1. Alkali fusion of Naphthalenesulfonic acids2. Alkaline hydrolysis of chloroNaphthalenes3. Hydroperoxidation of 2-isopropylNaphthalene to form 2-naphthol and acetone (not applicable to 1-naphthol)4. Dehydrogenation of tetralones5. Direct, single-step replacement of the amino group of naphthylamine by a hydroxyl groupNaphthols resemble phenols in their chemical properties, but their hydroxyl groups are more reactive. For example, they are readily converted to ethers by reaction with alcohols, and to amines by heating with ammonia and bisulfite (Bucherer reaction).3.1. 1-Naphthol
1-Naphthol [90-15-3 ] (15 ), α-naphthol, 1-naphthalenol, 1-hydroxyNaphthalene, C10 H8 O, M r 144.16, forms colorless prisms (from toluene) which darken on exposure to air or light. The compound is steam volatile and sublimable. Other physical properties are listed in Table 3
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