Met_OrgSynthesis

8.Memorize the following words and word combinations.

9.Answer the questions given.

1)What are the three distinct steps of addition polymerization?

2)What compounds serve as typical initiators in the chain-initiation step?

3)What are the specific features of addition polymerization?

4)What are the reactive active centers for each of the three types of addition polymerization?

5)What are carbocation and carbanion?

6)Can you guess on the base of information obtained from the previous text, how organometallic complex can be called in other words?

7)Are there any conditions under which no polymerization occurs?

8)What new information have you obtained from the text as compared to the previous one?

10. Read the text below to get more information on step-growth polymerization. Step-growth polymerization

Step-growth polymerization involves a chemical reaction between multifunctional monomer molecules. In a step-growth reaction, the growing chains may react with each other to form even longer chains. This applies to chains of all lengths. Thus, a monomer or dimer may react in just the same way as a chain hundreds of monomer units long. This is in contrast to a chain-growth polymerization, where only monomers may react with growing chains (In chaingrowth polymerization, two growing chains can’t join together the way they can in a step-growth polymerization).

The most common class of step-growth polymerization is called condensation polymerization and the product a condensation polymer, because the chemical reaction by which the monomer molecules bond is often a condensation reaction that produces a small molecule byproduct. A multifunctional monomer is a molecule that has more than one potential reactive site by which it can form intermolecular chemical bonds. The easiest way to visualize a step growth polymerization is a group of people holding hands to form a human chain: each person has two hands (=reactive sites).

A pioneer in step-growth polymerization is Wallace Carothers who invented nylon, a condensation product of hexamethylene diamine and adipic acid. Each monomer has two functional groups (two amino groups or two carboxyl group) and so each monomer can form an amide link with each of its neighbour.

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The functionality of a monomer is the number of reactive sites. A functionality of 2 will yield a linear polymer. For instance, hexamethylene diamine and adipic acid create nylon, terephthalic acid and ethylene glycol create PET (Polyethylene terephthalate).

In theory the polymerization will continue to result in a single macromolecule. The relationship between the extent of the reaction and the average number of

monomer units in a polymer chain is given by the Carothers equation. High molecular weight polymer is formed only at high degrees of conversion (extent of reaction). In practice the average length of the polymer chain is limited by such things as the purity of the reactants and the viscosity of the medium.

A monomer with functionality 3 will introduce branching in a polymer and will ultimately form a cross-linked macrostructure. The point at which this threedimensional structure is formed is known as the gel point because it is signalled by an abrupt change in viscosity. One of the earliest so-called thermosets is known as bakelite.

11. Memorize the following words and word combinations.

внутримолекулярные химические связи, давать, продолжение реакции, среднее число, чистота, вязкость среды, представлять, резкое изменение.

13. Answer the questions given.

1)What length can chains have in step-growth reaction?

2)What is the difference between chain-growth and step-growth polymerizations?

3)How can you visualize the step-growth polymerization? Can you suggest any other way of showing this type of polymerization?

4)What did you learn about nylon?

5)What kind of relationship does Carothers equation explain?

6)How is the average length of the polymer limited in practice?

7)What is a functionality? Compare monomers with functionality 2 and 3.

8)What is a gel-point?

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PART II. PETROCHEMICAL INDUSTRY

TEXT 1. GENERAL PROPERTIES OF PETROLEUM

A.Petroleum is a mixture of naturally occurring hydrocarbons which may exist in solid, liquid, or gaseous states, depending upon the conditions of pressure and temperature to which it is subjected. Almost all of the petroleum produced from the earth is either liquid or gas, and commonly, these materials are referred to as either crude oil or natural gas.

B.A typical hydrocarbon consists of:

(1)11 to 13 weight percent hydrogen.

(2)84 to 87 weight percent carbon.

(3)Traces of nitrogen, sulfur, oxygen, and helium may be found as impurities in crude petroleum. A low sulfur content results in a "sweet" crude oil and a high sulfur content is classified as a "sour" crude oil.

Although all petroleum is constituted primarily of carbon and hydrogen, the molecular constitution of crude oils differs widely. About 18 series of hydrocarbons have been recognized in crude petroleum.

C. Of these series, the most commonly encountered are the paraffins, naphthenes, olefines and aromatics.

Paraffins are hydrocarbons that are the richest in hydrogen and most stable. There are two types, straight-chain paraffins and branched-chain paraffins. Of

the two types, the branched-chain paraffins are preferred for their higher octane number and anti-knock characteristics in gasolines.

Naphthenes are closed-chain hydrocarbons, generally very stable and are primarily found as a component of lubricating oils.

Olefines are characterized by having at least one double bond between some of the carbon atoms. This means that at least two carbon atoms are joined with each other rather than a hydrogen atom. As with paraffins, olefines can be either straight chained or branch-chained molecules. Because of their double bonds, olefines are highly reactive with other elements and make them unsatisfactory for use in fuels that need a high degree of stability. However, olefines are an essential part of petrochemicals such polypropylene and butyl rubber, used in tire inner tubes.

Aromatics are characterized by at least one six-membered ring of carbon atoms. These molecules are known as aromatics because of their pleasant odour. Aromatics are naturally occurring in crude oil and are desired for gasolines because of their anti-knock qualities. However, the aromatics also tend to dissolve some types of rubber. Aromatics such as toluene were used during World War II to manufacture TNT and aviation gasolines. Today, toluene is used in solvents and other petrochemicals.

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Tasks on the text

1.Memorize the following words and word combinations.

2.Read part A and explain the meanings of the words “petroleum”, “crude oil”, “natural gas”.

3.Read part B and speak on the composition of petroleum.

4.Read part C and correlate the principles of hydrocarbon classification with those you have already read about in the previous texts.

5.Read part C once again and say how paraffins (naphthenes, olefines and aromatics) are applied in petrochemical industry and what special characteristics of these hydrocarbons specify their applications.

6.Make a report on general properties of petroleum.

7.Look through the text below and say what it is about. Give a title to the text.

Mixtures of volatile hydrocarbons are now used in preference to the chlorofluorocarbons as a propellant for aerosol sprays, due to chlorofluorocarbons impact on the ozone layer.

Methane [1C] and ethane [2C] are gaseous at ambient temperatures and cannot be readily liquified by pressure alone. Propane [3C] is however easily liquified, and exists in “propane bottles” mostly as a liquid. Butane [4C] is so easily liquified that it provides a safe, volatile fuel for small pocket lighters. Pentane [5C] is a clear liquid at room temperature, commonly used in chemistry and industry as a powerful nearly odourless solvent of waxes and high molecular weight organic compounds, including greases. Hexane [6C] is also a widely used non-polar, nonaromatic solvent, as well as a significant fraction of common gasoline.

The [6C] through [10C] alkanes, alkenes and isomeric cycloalkanes are the top components of gasoline, naphtha, jet fuel and specialized industrial solvent mixtures. With the progressive addition of carbon units, the simple non-ring structured hydrocarbons have higher viscosities, lubricating indices, boiling points, solidification temperatures, and deeper colour. At the opposite extreme from [1C] methane lie the heavy tars that remain as the lowest fraction in a crude oil refining retort. They are widely utilized as roofing compounds, pavement composition, wood preservatives and as extremely high viscosity liquids.

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8.Memorize the following words and word combinations.

9.What class of hydrocarbons do the compounds enlisted in the third passage belong to? Use the general molecule formula of this class and define the chemical formulae of them.

10.Speak on the fields of hydrocarbons applications according depending on the number of their carbon atoms.

11.Find the definition for each of the words given.

1.Another name for alkane.

2.A yellow solid: used chiefly as a high explosive and is also an intermediate in the manufacture of dyestuffs. Formula: CH3C6H2(NO2)3.

3.Petroleum before it has been refined.

4.A measure of the quality of a petrol expressed as the percentage of isooctane in a mixture of isooctane and n-heptane that gives a fuel with the same antiknock

(антидетонационный) qualities as the given petrol.

5.Any of a class of cycloalkanes, mainly derivatives of cyclopentane, found in petroleum.

6.A colourless volatile flammable liquid with an odour resembling that of benzene, obtained from petroleum and coal tar and used as a solvent and in the manufacture of many organic chemicals. Formula: C6H5CH3.

7.A compound, such as lead tetraethyl (тетраэтилсвинец), added to petrol to reduce knocking (детонация) in the engine.

8.A copolymer of isobutene and isoprene, used in tyres and as a waterproofing material.

9.Any one of various volatile flammable liquid mixtures of hydrocarbons, mainly hexane, heptane, and octane, obtained from petroleum and used as a solvent and a fuel for internal-combustion engines. Usually contains additives such as antiknock compounds and corrosion inhibitors.

10.Containing no sulphur compounds.

11.Another name for alkene.

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12.Containing a relatively large amount of sulphur compounds.

13.Any of various gaseous compounds of carbon, hydrogen, chlorine, and fluorine, used as refrigerants, aerosol propellants, solvents, and in foam: some cause a breakdown of ozone in the earth's atmosphere.

14.A distillation product from petroleum boiling in the approximate range 100-200 °C and containing aliphatic hydrocarbons: used as a solvent and in petrol.

15.A liquid alkane existing in five isomeric forms that are found in petroleum and used as solvents. Formula: C6H14

16.Something that provides or causes propulsion, such as the explosive charge in a gun or the fuel in a rocket.

12. Translate the sentences given.

1.В химии парафин – общее название для алкановых углеводородов с общей

формулой CnH2n+2, хотя в большинстве случаев оно относится к линейным алканам, в то время как разветвленные, или изоалканы, называются изопарафинами. Название парафин произошло от латинского parum «едва» + affinis «родство», что значит «мало родственный» или «с недостающей реактивностью».

2.Простейшей молекулой парафина является молекула метана (CH4), газа при комнатной температуре. Более тяжелые элементы ряда, как, например,

октан (C8H18), проявляют себя как жидкости при комнатой температуре. Твердые формы парафина, называемые твердым парафином (paraffin wax), - это

тяжелейшие молекулы от C20H42 до C40H82.

3.Пропилен (согласно ИЮПАК – пропен) – органическое соединение с

химической формулой C3H6. Это второй простейший представитель класса алкенов, где этилен (этен) простейший. При стандартных температуре и давлении пропен – бесцветный, легко воспламеняющийся газ.

4.Так как пропилен, как и большинство других газообразных углеводородов, не имеет запаха, его смешивают с незначительным количеством меркаптанов и сернистыми соединениями с мощным запахом чеснока, чтобы сделать пропилен более легко распознаваемым. Пропилен выделяют из каменноугольного газа или синтезируют путем крекинга нефти. Его применяют в основном как мономер, главным образом для производства полипропилена.

5.Толуол, также известный как метилбензол или фенилметан, - это прозрачная, нерастворимая в воде жидкость с типичным запахом разбавителя для краски (paint thinner), напоминающим сладкий запах родственного соединения бензола. Это ароматический углеводород, который широко используется как промышленное сырье и как растворитель.

6.Толуол – обычный растворитель, способный растворять: краски, разбавители красок, кремнийорганические герметики (silicone sealants), химические реактивы, резину, печатную краску, склеивающие вещества (клеи), лаки и дезинфицирующие средства. Он также может быть использован в производстве полиуретановой пены и тринитротолуола.

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TEXT 2. THE PETROLEUM-CHEMICAL INDUSTRY

The petroleum-chemical industry as we know it today is of comparatively recent origin, but it has some interesting antecedents. In 1854, before Drake’s oil well was drilled, Professor Silliman of Yale University, after analyzing samples of Pennsylvanian oil, mentioned the possibility of using petroleum products for purposes other than lighting and heating. In 1872 the famous Russian chemist Mendeleyev, after a visit to Pennsylvania, reported to his government: “This material (oil) is far too precious to be burnt. When burning oil, we burn money; it should be used as a chemical base material”.

Comparison with the petroleum industry. Quantitatively the petroleumchemical industry is not very large compared with the petroleum industry as a whole, only 2-3% of the oil and natural gas produced being used as a base material for the manufacture of chemicals. But the value of the products per unit weight is considerably higher than that of oil products, and the manufacturing processes are much more complex than the relatively simple separation, conversion and treating processes of oil manufacture.

Oil products are manufactured in large amounts in a relatively small number of standard grades; chemicals are manufactured in relatively smaller amounts in great diversity. Oil products and their manufacturing processes tend to remain stable for long periods; chemical manufacturing processes are subject to more frequent change as new processes are developed or new catalysts are discovered for quicker or cheaper production.

The sequence of operations in oil and chemical manufacture is practically the same; feedstock is selected and processed, the product is treated to bring it up to marketing specification, or various products are blended together to a formulation for specific applications. In both the oil and the chemical industries more care has to be taken in the selection of feedstocks for catalytic processes than for noncatalytic processes. For example, to produce isopropyl alcohol from the propane/propylene fraction of cracking gas, a propane content of about 40% will suffice, but for the manufacture of polypropylene plastic by catalytic process, a minimum of 99.55 is essential.

Oil refining is based on continuous operations, with few exceptions. Continuous operations are employed wherever possible for chemical manufacture, but there are more occasions when batch operation is advantageous in carrying out a complicated process.

Many chemicals, especially fine chemicals, are produced to specifications calling for a high degree of purity, and therefore often require some final treatment to bring them up to specification. Where chemicals have to be blended to produce products for specific applications the formulae are more complex than those of oil products. Pesticides, containing toxic compounds, have to be blended to be specific for particular pests and crops without any hazard to other living organisms, including man; detergents must have balanced wetting, cleaning and foaming properties as well as being readily degraded biologically in sewage treatment.

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2. Look through the text to find the following verbs, translate and memorize them.

To drill, to mention, to report, to burn, to compare, to treat, to manufacture, to tend, to remain, to develop, to select, to process, to blend, to carry out, to call for, to include, to degrade.

3.Find the following words and word combinations, give their Russian equivalents and memorize them.

Is of comparatively recent origin, oil well, for purposes other than lighting and

heating, quantitatively, as a whole, per unit weight, the manufacturing processes, relatively simple separation, oil manufacture, in large amounts, are subject to, the sequence of operations, is practically the same, continuous operation, with few exceptions, wherever possible, a high degree of purity, therefore, final treatment, foaming properties.

4. Find the pairs of synonyms.

Apply, complex, clean, call for, blend, manufacture, conversion, mix, complicated, production, pure, use, transformation, require.

5. Find the pairs of antonyms.

Complex, advantage, continuous operation, high, stable, simple, disadvantage, batch operation, unstable, low.

6. Translate the following phrases.

Considerably higher, much more complex, smaller amounts, more frequent change, quicker and cheaper production, more complicated process.

7. Copy out all adverbs and give their corresponding adjectives.

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8.State the form and the function of the Infinitive in the following sentence. Translate it into Russian.

This material is far too precious to be burnt.

9.Copy out all the predicates in the Passive voice with their subjects and translate them.

10.Finish the sentences.

1)The petroleum-chemical industry is of comparatively recent … 2) Professor Silliman mentioned the possibility of using petroleum products for purposes other than … 3) When burning oil, we burn … 4) The product is treated to bring it up to … 5) New processes are developed for quicker or cheaper … 6) The sequence of operations in oil and chemical manufacture is practically … 7) Fine chemicals production call for a high … 8) Batch operation is advantageous in carrying out a …

11.Translate the following sentences with modal verbs.

1)Oil should be used as a chemical base material. 2) Acetone is to be used as a solvent. 3) Great care has to be taken in the selection of feedstocks for catalytic processes. 4) These chemicals have to be blended to produce products for specific application.

12.Translate into English.

Первая скважина в Америке была пробурена в 1959 году. Нефтяные продукты использовались, как правило (as a rule), для освещения и обогрева. Но еще более 100 лет назад великий русский химик И.Д. Менделеев говорил о том, что нефть должна использоваться в качестве химического сырья.

В 1917 г. был разработан процесс получения ацетона из пропилена. Многие нефтяные компании США (Ease, Shell, Standard Oil) начали производство химических продуктов в 1930. Олефины в качестве сырья получали из термического крекинга нефтяных фракций.

После второй мировой войны с реконструкцией нефтепромышленности в западной Европе нефтехимическая промышленность развивалась там быстрее, чем в Восточной.

13. Learn the following dialogue.

-Oil refining is based on continuous operation and what about chemical manufacture?

-Continuous operations are employed wherever possible, but there are more occasions when batch operations are used.

-I think chemicals specifications call for high degree of purity.

-You are quite right. Many chemicals therefore often require some final treatment.

-What treatment do you mean?

-Some chemicals have to be blended and their formulae are more complex than those of oil products.

-Yes, I see. Thank you for your kind information.

14. Look through Text A and Text B and say what they are about.

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TEXT A

Chemicals from petroleum can be divided into two main groups, organic and inorganic. The former have a carbon skeleton and are basically composed of carbon, hydrogen and certain other elements, notably oxygen, chlorine, sulphur and nitrogen. The latter, for example, ammonia, sulphur and hydrogen peroxide, do not contain carbon and are much less numerous than the former, but are nevertheless manufactured in considerable quantities.

Chemicals can be further classified as ‘specification’ chemicals and ‘performance’ chemicals. Specification chemicals, for example, ammonia, ethyl alcohol, acetone, glycerol, are in the main well-established chemicals common to the chemical industry as a whole, irrespective of their origin. They are produced to establish specifications and are marketed as such for whatever purpose the buyer has in mind. Performance chemicals, on the other hand, have usually been developed for some specific application and many of them owe their existence to the petroleumchemical industry, for example, synthetic detergents, pesticides, synthetic resins. Many of them, as marketed, are blends of several chemicals, often to a proprietary formulation.

The range of products now derived from petroleum is so wide that they cannot all be discussed in this article and the range will undoubtedly continue to grow. Moreover, chemicals from petroleum are often not final products but intermediates and starting materials for other industries.

TEXT B

Chemical plants in the petroleum-chemical industry are analogous to refineries in the petroleum industry. They employ a number of continuous physical operations such as distillation, extraction, filtration, mixing and pumping during which no change in the chemical structure of the material occurs. The equipment used is very similar to that used in the corresponding oil operations, but the individual units are usually smaller, since the volume of chemicals handled by a chemical plant is generally less than the output of an oil refinery.

The manufacture of chemicals also involves many complex chemical conversion processes, the reaction conditions of which are very precise requiring careful control of temperature, pressure, reaction velocity and throughput, and these factors determine the nature and dimensions of the equipment.

Although fully continuous processes similar to those in the oil industry are preferred, batch reactions are common in the production of rather complex and expensive chemicals in relatively small quantities.

Many chemicals are corrosive and the materials used in the construction of equipment must be suitably chosen. Stainless steel and special alloys incorporating metals such as titanium and tantalum are widely employed, but are expensive. Glass and plastics are frequently used as linings of reaction vessels where lead was formerly used.

15. Give titles to both texts. Say what is common for both of them?

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