Met_OrgSynthesis

6.Translate from Russian into English.

1.Циклоалкены или циклоолефины – это тип непредельных углеводородов, которые имеют замкнутое кольцо атомов углерода, но не ароматического типа. Некоторые циклоалкены, такие как циклобутен и циклопентен, могут использоваться как мономеры для производства полимерных цепочек.

2.Циклоалкин – это углеводород, который является циклическим аналогом алкина. Он состоит из замкнутого кольца атомов углерода, содержащих одну или более тройную связь. Из-за линейной природы C-CΞC-C соединения алкина, циклоалкины имеют весьма натянутую связь и могут существовать, только когда число атомов углерода в кольце достаточно велико, чтобы обеспечить гибкость, соответствующую такой структуре. Соответственно,

циклооктин (C8H12) – это наименьшее соединение, которое может быть выделено и храниться как устойчивое соединение. Несмотря на это, меньшие циклоалкины могут быть получены и удержаны подходящим реагентом.

3.Простые ароматические кольца могут быть гетероциклическими, если они содержат неуглеродные атомы в кольце, например кислород, азот или серу. Они могут быть моноциклическими, как бензол, бициклическими, как нафталин или полициклическими, как антрацен (anthracene). Простые моноциклические кольца – кольца с пятью элементами как пиррол (pyrrole) или кольца с шестью элементами как пиридин. Объединенные ароматические кольца состоят из моноциклических колец, c общими соединяющими связями.

4.Некоторые арены являются полиароматическими углеводородами, они также называются полициклическими или много(поли)ядерными. Они состоят из более чем одного ароматического кольца. Простейшими являются

бензоциклопропен (C7H6), бензоциклопропан (C7H8), бензоциклобутадиен (C8H6), и бензоциклобутен (C8H8). Общие примеры – это нафталин с двумя объединенными кольцами, антрацен с тремя, тетрацен с четырьмя и пентацен с пятью линейно соединенными кольцами.

5.Пиридин – простое ароматическое гетероциклическое соединение с

химической формулой C5H5N, используемый как растворитель и реагент. Структурно он родственен бензолу, у которого одна CH-группа в ароматическом кольце замещена атомом азота. Он существует как бесцветная жидкость, с отчетливым, неприятным, похожим на рыбный, запахом. Пиридин промышленным путем первоначально получали из каменноугольной смолы. В настоящее время его синтезируют из формальдегида, аммиака и ацетальдегида.

6.Фуран – это гетероциклическое органическое соединение. Его выделяют путем термического разложения моносахарид (pentose)-содержащих материалов, целлюлозных твердых веществ, особенно древесины хвойных пород (pine wood). Фуран – бесцветная, легко воспламеняющаяся, летучая жидкость, с точкой кипения, близкой к комнатной температуре. Он токсичен и может быть канцерогенным.

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TEXT 8. POLYMERS. INTRODUCTION INTO

POLYMERIZATION

One important property of carbon is that it can form certain compounds, the individual molecules of which are capable of attaching themselves to one another, thereby forming a three-dimensional network or a chain. The process is called polymerization and the long molecular chains or networks – polymers, while the source compound is a monomer. Polymers artificially manufactured are referred to as synthetic polymers and naturally occurring as biopolymers.

Synthetic polymers. Traditionally, the industry has produced two main types of synthetic polymer – plastics and rubbers. The distinction is that plastics are, by and large, rigid materials at service temperatures while rubbers are flexible, low modulus materials which exhibit long-range elasticity. Plastics are further subdivided into thermoplastics and thermosetting plastics (thermosets), the latter type being materials where the long chains are linked together by crosslinks, a feature they share with conventional vulcanized rubbers.

However, the distinction in terms of stiffness has become blurred by the development of thermoplastic elastomers (TPEs). Moreover, all polymers, irrespective of their nature, can be reinforced by a very wide range of fillers to produce composite materials.

A polymer is chemically described by its degree of polymerisation, molar mass distribution, tacticity, copolymer distribution, the degree of branching, by its endgroups, crosslinks, crystallinity and thermal properties such as its glass transition temperature and melting temperature. Polymers in solution have special characteristics with respect to solubility, viscosity and gelation.

With a single monomer as a start the product is a homopolymer. Further, secondary component(s) may be added to create a heteropolymer (co-polymer) and the degree of clustering of the different components can also be controlled. Physical characteristics, such as hardness, density, mechanical or tensile strength, abrasion resistance, heat resistance, transparency, colour, etc. will depend on the final composition.

Polymerization. In more straightforward polymerization, alkenes, which are a relatively stable form polymers through relatively simple radical reactions. Conversely, more complex reactions such as those that involve substitution at the carbonyl atom require more complex synthesis due to the way in which reacting molecules polymerize.

As alkenes can be formed in somewhat straightforward reaction mechanisms, they form useful compounds such as polyethylene and polyvinyl chloride (PVC) when undergoing radical reactions, which are produced in high tonnages each year due to their usefulness in manufacturing processes of commercial products, such as piping, insulation and packaging. Polymers such as PVC are generally referred to as "singular" polymers as they consist of repeated long chains or structures of the same monomer unit, whereas polymers that consist of more than one molecule are referred

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to as "co-polymers".

Other monomer units, such as formaldehyde hydrates or simple aldehydes, are able to polymerize themselves at quite low temperatures (>-80oC) to form trimers; molecules consisting of 3 monomer units which can cyclize to form ring cyclic structures, or undergo further reactions to form tetramers, or 4 monomer-unit compounds. Further compounds either being referred to as oligomers in smaller molecules.

Tasks on the text

1.Memorize the following words and word combinations.

1.	rubber [	] – резина, каучук		17.gelation [	] – 1)застывание,
2.	by and large – в общем и целом, в			загущение, 2)гелеобразование
	общем			18.homopolymer – гомополимер
3.	low-modulus materials – материалы			19.heteropolymer – сополимер
	с низким модулем упругости			20.clustering – образование скоплений,
4.	thermoplastic [,		] –	группировка, кластеризация;
	термопласт, термопластическая			21.tensile [	] strength – предел
	пластмасса			прочности на разрыв, прочность на
5.	thermosetting plastic, thermoset –			растяжение; сопротивление
	реактопласт, термореактивный			22.abrasion [	] resistance –
	пластик, пластмасса			износостойкость, абразивная
6.	crosslink – поперечная			стойкость, прочность на истирание
	(межмолекулярная) связь			23.transparency [	] –
7.	vulcanized [		] rubber –	прозрачность

вулканизат

8.stiffness – жёсткость; прочность; тугость

9.blurred [ ] – неясный,

туманный; расплывчатый

10.thermoplastic elastomers (TPEs) –

термоэластопласт, термопластовый эластомер

11.to reinforce [, ] –

укреплять, усиливать 12.filler – наполнитель 13.tacticity – регулярность

(симметричность) молекулярной структуры

14.end group – концевая группа

15.crystallinity – кристалличность, упорядоченность структуры

16.glass transition temperature –

температура стеклования

24.straightforward [, ] –

прямой; движущийся прямо вперёд

25.radical reaction – реакция с участием/выделением свободных радикалов, радикальная реакция

26.conversely – обратно; назад; наоборот

27.to undergo – 1) испытывать, переносить 2)подвергаться(чему-л.)

28.piping [`	] – трубопровод;
система труб
29.insulation [	] – 1)

изоляция 2)изоляционный материал

30.packaging – упаковка

31.hydrate [	] – гидрат,
гидроокись
32.trimer [`	] – тример

33.tetramer – тетрамер

34.oligomer – олигомер (полимер с низкой молекулярной массой)

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2.Practise the pronunciation of the words. Make sure you remember their

meanings.
Polymerization[	], thereby[,	], monomer [	],
biopolymer [	], polyethelene [	], polyvinylchloride, PVC
[	s ], copolymer [	], whereas [	],
formaldehyde [	], aldehyde [	].

3. Translate the following words and word combinations into Russian:

Thereby, source compound, exhibit long-range elasticity; degree of brunching, melting temperature, irrespective of; with respect to, degree of clustering, heat resistance, straightforward polymerization, radical reactions, conversely, due to, somewhat, whereas.

4.Choose the proper English equivalents from the right column.

a)	гибкие материалы;	1)	thermoplastic elastomers;
b)	твердые материалы;	2)	rigid materials;
c)	материалы с низким модулем упругости;	3)	thermosetting plastics;
d)	термопластики;	4)	tensile strength;
e)	термореактивные пластики;	5)	abrasion resistance;
f)	термоэластопласты;	6)	low modulus materials;
g)	прочность на растяжение;	7)	heat resistance;
h)	прочность на истирание;	8)	flexible materials;
i)	рабочая температура;	9)	thermoplastics;
j)	температура стеклования;	10)	glass transition temperature;
k)	термостойкость.	11)	service temperature.

5.Read the text, find the following parts of the sentences and translate them

into Russian. Define the grammatical forms of the underlined words.

Capable of attaching themselves; artificially manufactured; naturally occurring; fine tuned; reacting compounds; when undergoing radical reactions; compounds being referred to.

6. Fill in the gaps with the words given. Be attentive: some words are odd.

Transparency, carbon, biopolymers, chemical characteristics, synthetic polymers, thermal properties, specific use, thermoplastics, thermosetting plastics, tetramers, physical characteristics, ring cyclic structures, tensile strength, monomer, crosslinks, crystallinity, final composition, tacticity, homopolymer, polyethylene, heteropolymer, simple aldehydes, trimers, polyvinyl chloride (PVC), formaldehyde hydrates, singular polymers , oligomers.

1.… is a source compound for forming chains or networks of polymers.

2.… are those artificially manufactured and are referred to as industrial polymers.

3.Plastics can be classified into … and … .

4.… of synthetic polymers are fine tuned for their specific use. They are as follows: hardness, density, mechanical or …, abrasion resistance, heat resistance, …, colour, etc.

5.… of a polymer are its glass transition temperature and melting temperature.

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6.… is created by adding secondary components to a … .

7.Polymers such as … and … are formed through relatively simple radical reactions.

8.Trimers are formed through self-polymerization at quite low temperatures of … or … .

9.… are formed through cyclizing of 3 monomer units reffered to as … .

10. ... are 4 monomer-unit compounds formed out of compounds with molecules consisting of 3 monomer units.

7. Say whether the statements below are true or false. Prove your point of view.

1.The process of polymerization can be called as the process, under which the individual molecules of carbon compounds are capable of separating themselves one from another, thereby forming a network or chain.

2.Co-polymer is a compound with a fixed unchangeable set of clusters.

3.Homopolymer is a start product of a single monomer.

4.Straightforward polymerization involves substitution at the carbonyl atom.

5.Complex reactions of polymerization require more complex synthesis.

6.Polymers such as PVC consist of repeated long chains of structures.

7.Polymers that consist of less than two molecules are called “singular”.

8.Compounds consisting of more than 4-monomer units are called oligomers.

8.Answer the questions given.

1)How can you describe the process of polymerization?

2)What is a monomer? What part does it play in the process of polymerization?

3)What is the difference between synthetic polymers and biopolymers?

4)What are the two generic groups of synthetic polymers?

5)Can you describe special characteristics polymers have in solution?

6)Can you name the chemical characteristics of polymers?

7)What is the degree of clustering?

8)What are the physical characteristics of polymers?

9)What polymers and what aliphatic compounds form in the simple polymerization reaction. How can you call such a polymerization reaction in this case?

10)What do complex reactions of polymerization involve and require?

11)What compounds do alkenes form?

12)In what way are polyethylene and polyvinylchloride useful in manufacturing processes?

13)What is the difference between singular polymers and co-polymers.

14)What are trimers? How are they formed?

15)What are tetramers? How are they formed?

9.Find the proper definition for each of the words given.

a)	monomer;	f)	heteropolymer (copolymer);	k)	viscosity;
b)	polymer;	g)	glass transition temperature;	l)	tensile strength;
c)	thermoplastic;	h)	polyethelene;	m)	oligomer;
d)	thermosetting plastics;	i)	crosslink;	n)	PVC.
e)	thermoplastic elastomer;	j)	solubility;

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1.A polymer derived from two (or more) monomeric species, as opposed to a homopolymer where only one monomer is used.

2.A large molecule (macromolecule) composed of repeating structural units typically connected by covalent chemical bonds. While the term in popular usage suggests plastic, it actually refers to a large class of natural and synthetic materials with a variety of properties and purposes.

3.A plastic that melts to a liquid when heated and freezes to a brittle, very glassy state when cooled sufficiently (достаточно).

4.A small molecule that may become chemically bonded to other monomers to form a polymer.

5.Polymer materials that irreversibly (необратимо) cure form. The cure may be done through heat (generally above 200 degrees Celsius).

6.The temperature at which an amorphous solid, such as glass or a polymer, becomes brittle on cooling, or soft on heating.

7.The characteristic physical property referring to the ability of a given substance, the solute, to dissolve in a solvent.

8.In chemistry, it consists of a limited number of monomer units, in contrast to a polymer which, at least in principle, consists of an unbounded number of monomers.

9.A measure of the resistance of a fluid which is being deformed by either shear stress or extensional stress. In general terms it is the resistance of a liquid to flow, or its "thickness". It describes a fluid’s internal resistance to flow and may be thought of as a measure of fluid friction.

10.The stress at which a material breaks or permanently deforms. Along with elastic modulus and corrosion resistance, it is an important parameter of engineering materials that are used in structures and mechanical devices. It is specified for materials such as alloys, composite materials, ceramics, plastics and wood.

11.A synthetic thermoplastic material made by polymerizing vinyl chloride. The properties depend on the added plasticizer. The flexible forms are used in hosepipes, insulation, shoes, garments, etc.

12.A class of copolymers or a physical mix of polymers (usually a plastic and a rubber) which consist of materials with both thermoplastic and elastomeric properties.

13.A polymer consisting of long chains of the monomer ethylene (IUPAC name ethene). The recommended scientific name polyethene is systematically derived from the scientific name of the monomer. In the polymer industry the name is sometimes shortened to PE in a manner similar to that by which other polymers like polypropylene and polystyrene are shortened to PP and PS respectively. In the United Kingdom the polymer is commonly called polythene, although this is not recognized scientifically.

14.A chemical bond, atom, or group of atoms that connects two adjacent chains of atoms in a large molecule such as a polymer or protein.

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TEXT 9. CHAIN-GROWTH AND STEP-GROWTH

POLYMERIZATION

Chain-growth. Chain-growth polymerization or addition polymerization involves the linking together of molecules incorporating double or triple chemical bonds. These unsaturated monomers (the identical molecules which make up the polymers) have extra internal bonds which are able to break and link up with other monomers to form the repeating chain. Addition polymerization is involved in the manufacture of polymers such as polyethylene, polypropylene and polyvinyl chloride (PVC).

In the polymerization of ethylene, its pi bond is broken and these two electrons rearrange to create a new propagating center like the one that attacked it. The form this propagating center takes depends on the specific type of addition mechanism. There are several mechanisms through which this can be initiated. The free radical mechanism was one of the first methods to be used. Free radicals are very reactive atoms or molecules which have unpaired electrons. Taking the polymerization of ethylene as an example, the free radical mechanism can be divided into three stages: chain initiation, chain propagation and chain termination.

Free radical addition polymerization of ethylene must take place at high temperatures and pressures, approximately 300°C and 2000 At (atmosphere). While most other free radical polymerizations do not require such extreme temperatures and pressures, they do tend to lack control. One effect of this lack of control is a high degree of branching. Also, as termination occurs randomly, when two chains collide, it is impossible to control the length of individual chains. A newer method of coordination polymerization similar to free radical, but allowing more control involves the Ziegler-Natta catalyst especially with respect to polymer branching.

Other forms of addition polymerization include cationic addition polymerization and anionic addition polymerization. While not used to a large extent in industry yet due to stringent reaction conditions such as lack of water and oxygen, these methods provide ways to polymerize some monomers that cannot be polymerized by free radical methods such as polypropylene.

Step-growth. Step growth polymers are defined as polymers formed by the stepwise reaction between functional groups of monomers. Most step growth polymers are also classified as condensation polymers, but not all step growth polymers (like polyurethanes formed from isocyanate and alcohol bifunctional monomers) release condensates. Step growth polymers increase in molecular weight at a very slow rate at lower conversions and only reach moderately high molecular weights at very high conversion (i.e. >95%).

To solve inconsistencies in these naming methods, adjusted definitions for condensation and addition polymers have been developed. A condensation polymer is defined as a polymer that involves elimination of small molecules during its synthesis, or contains functional groups as part of its backbone chain, or its repeat unit does not contain all the atoms present in the hypothetical monomer to which it can be degraded.

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Tasks on the text

1.Memorize the following words and word combinations.

1.chain-growth – наращивание цепи

2.addition polymerization –

полиприсоединение

3.to incorporate – 1) включать,

содержать в себе 2) объединять

4. to propagate [ ] –

1)распространяться 2) развиваться

5.chain initiation – инициация,

возникновение цепи

6.chain propagation – развитие,

распространение цепи

7.chain termination – обрыв цепи

8. to collide [ ] –

1)сталкиваться; соударяться

9.Ziegler-Natta catalyst – катализатор Циглера, катализатор

стереорегулярной полимеризации 10.branching – разветвление

11.cationic [,	] –
катионоактивный
12.anionic–	]
анионоактивный

13.stringent [

] – 1)жесткий;

2)с наложенными ограничениями;

3)строгий; 4) точный

14.stepwise – ступенчатый, пошаговый

15.condensation polymer –

конденсационный полимер

16.isocyanate [, ] –

изоцианат

17.moderately [ ] –

1)умеренно, сдержанно; 2) средне

18.conversion – 1) превращение; преобразование; переход

19.inconsistency – противоречивость,

несогласованность
20.adjusted [	] –

отрегулированный, установленный 21.elimination – удаление, устранение

22.backbone chain – основная цепь макромолекулы

23.repeat(ing) unit – повторяющееся звено, структурная единица

24.to degrade – разрушать, портить

2.Look through the text and find the following word combinations in it.

Translate them into Russian.

Chain-growth polymerization; incorporating together; extra internal bonds; repeating chain; propagating center; do tend to lack control; coordination polymerization step growth polymers; release condensates; at a very slow rate; at very high conversion; adjusted definitions.

3.Translate the following word combinations into English.

Двойные или тройные химические цепи; механизм присоединения; неспаренные электроны; проходить при крайних температурах и давлениях; использоваться в большой степени; жесткие условия протекания реакции; ступенчатая реакция; увеличиваться в молекулярной массе; разрешить несоответствие.

4.Answer the following questions.

1)What way does addition polymerization take place?

2)Manufacture of what polymers is addition polymerization involved in?

3)What is a propagating center? What does the form of it depend on?

4)What method is used for polymerization of ethylene?

5)What are the three stages of the free radical mechanism method?

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6)What conditions does addition polymerization take place under?

7)Why do most free radical polymerizations tend to lack control?

8)What are other forms of addition polymerization? What are they used for?

9)What are the reaction conditions for cationic addition polymerization and anionic addition polymerization?

10)What are step growth polymers? What are the peculiarities of their reaction of polymerization?

11)How can a condensation polymer be defined?

5. Speak on: a) four methods or forms of chain-growth polymerization;

b) polymerization of ethylene; c) step-growth polymerization.

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

a)	Ziegler-Natta catalyst;	e)	initiation;	h)	radical polymerization;
b)	condensation polymers;	f)	the repeat unit;	i)	coordination polymerization;
c)	chain propagation;	g)	polyurethane;	j)	backbone chain of a polymer.

d)chain termination;

1.Any class of polymers formed through a condensation reaction, releasing a small molecule by-product such as water or methanol, as opposed to addition polymers which involve the reaction of unsaturated monomers. These polymers include polyamides, polyacetals and polyesters.

2.A chemical reaction that triggers one or more secondary reactions. Often this reaction generates a reactive intermediate from a stable molecule which is then involved in secondary reactions. In polymerization, it is followed by a chain reaction and termination.

3.Any chemical reaction leading to the destruction of a reactive intermediate in a chain propagation step in the course of a polymerization, effectively bringing it to a halt.

4.A form of addition polymerization in which monomer adds to a growing macromolecule through an organometallic active center. The development of this polymerization technique started in the 1950s with heterogeneous ZieglerNatta catalysts based on titanium tetrachloride and an aluminium co-catalyst such as methylaluminoxane. The polymerization has a great impact on the physical properties of vinyl polymers such as polyethylene and polypropylene compared to the same polymers prepared by other techniques such as free radical polymerization.

5.A reagent or a mixture of reagents used in the production of polymers of 1- alkenes (α-olefins). These catalysts are typically based on titanium compounds and organometallic aluminium compounds. They represent a major breakthrough in polymerization chemistry because they produce a variety of commercially important polymers and can be highly stereoselective.

6.A type of polymerization in which the reactive center of a polymer chain consists of a radical. The polymerization reaction is initiated by three classes of free-radical initiators.

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7.The series of covalently-bonded atoms that together create the continuous chain of the molecule.

8.A process in which a reactive intermediate is continuously regenerated during the course of a chemical reaction. In polymerization reaction, the reactive endgroups of a polymer chain react in each propagation step with a new monomer molecule transferring the reactive group to that last unit.

9.An essential concept which defines polymer structure, the simplest structural unit of a polymer chain. So a polymer consists of the units linked together, like the beads of a necklace.

10.Commonly abbreviated PU, any polymer consisting of a chain of organic units joined by urethane links. Such a polymer is formed by reacting a monomer containing at least two isocyanate functional groups with another monomer containing at least two alcohol groups in the presence of a catalyst.

7.Read the text below to get more information on addition polymerization.

Addition polymerization

Addition polymerization, also called polyaddition or chain growth polymerization, is a polymerization technique where unsaturated monomer molecules add on to a growing polymer chain one at a time.

The process takes place in three distinct steps:

1)chain initiation, usually by means of an initiator which starts the chemical process. Typical initiators include any organic compound with a labile group: e.g. azo (-N=N-), disulfide (-S-S-), or peroxide (-O-O-).

2)chain propagation;

3)chain termination, which occurs either by combination or disproportionation. Termination, in radical polymerization, is when the free radicals combine and is the end of the polymerization process.

Addition polymerization unlike condensation polymerization (also known as step-growth polymerization) is specified by the following:

1)high molecular weight polymer is formed at low conversion;

2)no small molecules, such as H2O, are eliminated in this process;

3)new monomer adds on the growing polymer chain via the reactive active centre which can be: a) a free radical in free radical addition polymerization; b) a carbocation (an ion with a positively-charged carbon atom) in cationic addition polymerisation; c) a carbanion (an anion in which carbon has an unshared pair of electrons and bears a negative charge) in anionic addition polymerization; d) an organometallic complex in coordination polymerization;

4)above a certain ceiling temperature, no polymerization occurs.

Benzol peroxide and aluminium chloride can serve as examples of reaction initiators. Benzoyl peroxide is a radical initiator for the free radical addition polymerization of styrene to produce polystyrene.

Aluminium chloride is an initiator for the cationic addition polymerization of isobutylene to form isobutyl synthetic rubber.

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