Met_OrgSynthesis

TEXT 5. CHARACTERISTICS OF ORGANIC SUBSTANCES

Organic compounds are generally covalently bonded. This allows for unique structures such as long carbon chains and rings. The reason carbon is excellent at forming unique structures and that there are so many carbon compounds is that carbon atoms form very stable covalent bonds with one another (catenation). In contrast to inorganic materials, organic compounds typically melt, boil, sublimate, or decompose below 300 °C. Neutral organic compounds tend to be less soluble in water compared to many inorganic salts, with the exception of certain compounds such as ionic organic compounds and low molecular weight alcohols and carboxylic acids where hydrogen bonding occurs.

Organic compounds tend to dissolve in organic solvents which are either pure substances like ether or ethyl alcohol, or mixtures, such as the paraffinic solvents such as the various petroleum ethers and white spirits, or the range of pure or mixed aromatic solvents obtained from petroleum or tar fractions by physical separation or by chemical conversion. Solubility in the different solvents depends upon the solvent type and on the functional groups if present. Solutions are studied by the science of physical chemistry. Like inorganic salts, organic compounds may also form crystals.

A unique property of carbon in organic compounds is that its valency does not always have to be taken up by atoms of other elements, and when it is not, a condition termed unsaturation results. In such cases we talk about carbon double bonds or triple bonds. Double bonds alternating with single in a chain are called conjugated double bonds. An aromatic structure is a special case in which the conjugated chain is a closed ring.

Tasks on the text

1.Memorize the following words and word combinations.

1.	unique [ `	] – уникальный
2.	catenation [,	] –
	сочленение, соединение
3.	in contrast to – в отличие от
4.	to sublimate [`	] –
	сублимировать, возгонять, очищать
5.	soluble [`	] – растворимый

6.compared to – по сравнению с

7.with the exception of – за исключением

8. carboxylic [

] acid –

карбоновая кислота

9. to dissolve [ ] – растворять(ся), разлагать

10.solvent – растворитель

11.ether [`	] – простой эфир white
spirit – уайт спирит, нефтяной
скипидар
12.tar [ ] – смола
13.solution [		] – раствор,
растворение
14.unsaturation [		] –
ненасыщенность
15.triple [	] – тройной; утроенный
16.conjugated [		]
double bond – сопряженная
двойная связь
17.to alternate [`		] – сменять

друг друга; чередоваться, колебаться

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2.Choose the Russian equivalents from the right column.

1)	double bond;	a)	замкнутое кольцо;
2)	covalently bonded;	b)	случаться, иметь место;
3)	closed ring;	c)	ароматическая структура;
4)	conjugated chain;	d)	устойчивая ковалентная связь;
5)	occur;	e)	двойная связь;
6)	alcohol;	f)	спирт;
7)	aromatic structure;	g)	сопряженная цепь;
8)	stable covalent bond.	h)	ковалентно-связанный.

3.Choose the English equivalents from the right column.

1)	распадаться;	a)	conversion;
2)	чистый или смешанный;	b)	solubility;
3)	смесь;	c)	separation;
4)	молекулярный вес;	d)	mixture;
5)	превращение;	e)	pure or mixed;
6)	растворимость;	f)	range;
7)	отделение;	g)	decompose;

8)диапазон, пределы амплитуда, ряд. h) molecular weight.

4.Read, translate and define what parts of speech the words, their derivatives and related words belong to. Consult the dictionary, write out the meanings

and transcription to the words that are new for you.

Alternate – alternately – alternation – alternating – alternative – alternatively – alternativeness; converse – conversion – convert – converted; dissolvable – dissolvability – dissolve – dissolved – dissolver; mix – mixable – mixture; pure – pureness – purification – purify – purity; separate– separately– separation – separator.

5.Look trough the text and find the corresponding verbs denoting the following physical and chemical processes.

1.1) To combine or blend (ingredients, liquids, objects, etc.) together into one mass; 2) to become or have the capacity to become combined, joined;

2.to make purer, refine;

3.to change or cause to change from a liquid to a vapour so rapidly that bubbles of vapour are formed copiously (обильно) in the liquid;

4.to occur or cause to occur successively or by turns; 2) to swing repeatedly from one condition, etc., to another; 3) to interchange regularly or in succession;

5.1) to break down (organic matter) or (of organic matter) to be broken down physically and chemically by bacterial or fungal action; rot; 2) to break down or cause to break down into simpler chemical compounds; 3) to break up or separate into constituent parts;

6.1) to liquefy (a solid) or (of a solid) to become liquefied, as a result of the action of heat; 2) to become or make liquid; dissolve;

7.1) to go or cause to go into solution; 2) to become or cause to become liquid; melt.

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

a)	carboxylic acid;	c)	solvent;	e)	white spirit;	g)	tar;
b)	catenation;	d)	ether;	f)	petroleum ether;	h)	solubility.

1.Any of a class of organic acids containing the carboxyl group.

2.Any of various dark viscid (вязкий) substances obtained by the destructive distillation (сухая перегонка) of organic matter such as coal, wood, or peat.

3.A liquid capable of dissolving another substance.

4.A volatile (летучая) mixture of the higher alkane hydrocarbons, obtained as a fraction of petroleum and used as a solvent.

5.A colourless volatile highly flammable liquid with a characteristic sweetish odour, made by the reaction of sulphuric acid (серная кислота) with ethanol: used as a solvent and anaesthetic. Formula: C2H5OC2H5.

6.Arrangement in a series of chains or rings.

7.1) The ability of a substance to dissolve; the quality of being soluble 2)a measure of this ability for a particular substance in a particular solvent, equal to the quantity of substance dissolving in a fixed quantity of solvent to form a saturated solution under specified temperature and pressure. It is expressed in grams per cubic decametre, grams per hundred grams of solvent, moles per mole, etc.

8.A colourless liquid obtained from petroleum and used as a substitute for turpentine (терпентин – вязкая жидкость, выделяемая из хвойных деревьев).

7.Read the text and decide if the following statements are true or false.

1)Carbon is excellent at forming unique structures.

2)Carbon atoms form unstable covalent bonds with one another.

3)Like inorganic materials organic materials typically melt, boil, sublimate or decompose below 300°C.

4)Neutral organic compounds are more soluble in water than many inorganic salts.

5)Solutions are studied by the science of physical chemistry.

6)Solubility in the different solvents depends upon the solvent type.

7)Double bonds alternating with single in a chain are called triple bonds.

8.Answer the following questions.

1)Why is carbon excellent at forming unique structures?

2)What do organic compounds typically do below 300°C?

3)In what connection is the term “carboxylic acid” mentioned in the text?

4)Do organic compounds dissolve in organic solvents?

5)What substances are known as pure substances?

6)What is the difference between neutral organic compounds and many inorganic salts concerning their solubility in water?

7)Is it possible for organic compounds to form crystals?

8)What is a unique property of carbon in organic compounds?

9)When can we say that the conjugated chain is a closed ring?

9.Discuss the following with your partner: a) what is a covalent bond; b) what is unsaturation; c) what are conjugated double bonds?

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TEXT 6. HYDROCARBONS

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. With relation to chemical terminology, aromatic hydrocarbons (arenes), alkanes, alkenes and alkyne-based compounds composed entirely of carbon or hydrogen are referred to as "pure" hydrocarbons, whereas other hydrocarbons with bonded compounds or impurities of sulphur or nitrogen, are referred to as "impure", and remain erroneously referred to as hydrocarbons.

The classifications for hydrocarbons defined by IUPAC nomenclature of organic chemistry are as follows:

1.Saturated hydrocarbons (alkanes) are the most simple of the hydrocarbon species and are composed entirely of single bonds and are saturated with hydrogen; they are the basis of petroleum fuels and are either found as linear or branched species of unlimited number. The general formula for saturated hydrocarbons is CnH2n+2 (assuming non-cyclic structures).

2.Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms. Those with one double bond are called alkenes, with the

formula CnH2n (assuming non-cyclic structures). Those containing triple bonds are called alkynes, with general formula CnH2n-2.

3.Cycloalkanes are hydrocarbons containing one or more carbon rings to which hydrogen atoms are attached. The general formula for a saturated hydrocarbon containing one ring is CnH2n

4.Aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring.

Tasks on the text

1.	Memorize the following words and word combinations.
1) aromatic hydrocarbons –				9) IUPAC, International Union of Pure
	ароматические углеводороды			and Applied Chemistry – ИЮПАК,
2)	arenes [		] – арены,	Международный союз теоретической
	углеводороды ароматического ряда			и прикладной химии
3) alkanes [			] – алканы,	10)carbon backbone –углеродная цепь
	парафины			11)acyclic [	] – ациклический
4)	linear [	] – линейный		12)wax [	] – воск, парафин
5)	alkenes [		] – алкены,	13)ethene [`	] – этен, этилен
	непредельные (ненасыщенные)			14)rupture [	] – разрыв
	углеводороды, олефины			15)ethyne [`	] – этин, этилен
6)	alkynes [		] – алкины,	acetylene [	] – ацетилен
	углеводороды ацетиленового ряда			16) to hydrogenate [`		] –
7)	erroneously [		] – ложно;	гидрировать, гидрогенизировать
	неверно, неправильно, ошибочно			17)planar [	] – плоский
8)	nomenclature [		] –	18)benzene [	] – бензол
	номенклатура, перечень, список			19)ratio [	] – (со)отношение,
				пропорция, коэффицент

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A 3D model of ethylene, the simplest alkene

2.Read the text and answer the questions given.

1)What is a hydrocarbon?

2)What is the difference between pure and impure hydrocarbons?

3)What are saturated hydrocarbons?

4)What are alkenes and alkynes?

5)What are cycloalkanes?

6)What is an aromatic ring?

3.Read the texts below to get more information on hydrocarbons.

Alkanes

Alkanes, also known as paraffins, are chemical compounds that consist only of the elements carbon (C) and hydrogen (H) (i.e., hydrocarbons), wherein these atoms are linked together exclusively by single bonds (i.e., they are saturated compounds) without any cyclic structure (i.e. loops). Alkanes belong to a homologous series of organic compounds in which the members differ by a constant relative atomic mass of 14.

Each carbon atom must have 4 bonds (either C-H or C-C bonds), and each hydrogen atom must be joined to a carbon atom (H-C bonds).

A 3D model of methane, the simplest alkane

A series of linked carbon atoms is known as the carbon skeleton or carbon backbone. In general, the number of carbon atoms is often used to define the size of the alkane (e.g., C2-alkane).

The simplest possible alkane (the parent molecule) is methane, CH4. There is no limit to the number of carbon atoms that can be linked together, the only limitation being that the molecule is acyclic, is saturated, and is a hydrocarbon. Saturated oils and waxes are examples of larger alkanes where the number of carbons in the carbon backbone tends to be greater than 10.

Alkenes

In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to- carbon double bond. The simplest acyclic alkenes, with only one double bond and no other functional groups, form a homologous series of hydrocarbons with the general formula CnH2n.

The simplest alkene is ethylene (C2H4), which has the International Union of Pure and Applied Chemistry (IUPAC) name ethene.

The simplest alkenes, ethene, propene and butene are gases. Linear alkenes of approximately five to sixteen carbons are liquids, and higher alkenes are waxy solids.

Alkenes are relatively stable compounds, but are more reactive than alkanes due to the presence of a carbon-carbon pi-bond. The majority of the reactions of alkenes involve the rupture of this pi bond, forming new single bonds.

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Alkynes
Alkynes are hydrocarbons that have at least one triple
bond between two carbon atoms, with the formula CnH2n-2.
The alkynes are traditionally known as acetylenes or the
acetylene series, although the name acetylene is also used to
refer specifically to the simplest member of the series, known
as ethyne (acetylene) (C2H2) using formal IUPAC
nomenclature.	A 3D model
Unlike alkanes, and to a lesser extent, alkenes, alkynes	of acetylene, the
are unstable and reactive.	simplest alkyne

4.Look through the text about alkanes again and answer the questions given.

1)How are atoms linked together in alkane molecules?

2)What is the simplest alkane? What formula does it have?

3)How is each carbon atom characterized?

4)How can you define the size of an alkane?

5)What are the examples of larger alkanes?

6)What are the obligatory conditions for a molecule to be considered as an alkane?

7)What possible number of carbon atoms can exist in an alkane molecule?

5.Look through the texts about alkenes and alkynes again and answer the

questions given.

1)What is the difference in atomic bonds of alkenes and alkynes?

2)What are the names of the simplest alkenes and alkynes?

3)What are the physical properties of alkenes and alkynes?

6.Read the text below and make up questions of your own.

Aromatic hydrocarbon

An aromatic hydrocarbon (abbreviated as AH) or arene is a hydrocarbon, of which the molecular structure incorporates one or more planar sets of six carbon atoms that are connected by delocalised electrons numbering the same as if they consisted of alternating single and double covalent bonds.

The term “aromatic” was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent. This sweet scent actually came from impurities in the compounds (which are not actually aromatic in the sense initially described).

The configuration of six carbon atoms in aromatic compounds is known as a benzene ring, after the simplest possible such hydrocarbon, benzene. Aromatic hydrocarbons can be monocyclic or polycyclic.

General properties: 1) display aromaticity; 2) the carbon-hydrogen ratio is very large; 3) they burn with a sooty yellow flame because of the high carbon-hydrogen ratio.

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7. Read the text below and give the summary of it.

Cycloalkanes

	Cycloalkanes, also called naphthenes, are types of
	alkanes which have one or more rings of carbon atoms in
	the chemical structure of their molecules. Cycloalkanes
	consist of only carbon (C) and hydrogen (H) atoms and
	are saturated because there are no multiple C-C bonds to
	hydrogenate (add more hydrogen to).
	A general chemical formula for cycloalkanes would
	be CnH2(n+1-g) where n = number of C atoms and g =	Cylobutane
	number of rings in the molecule.
	Cycloalkanes with a single ring are named analogously to their normal alkane

counterpart of the same carbon count: cyclopropane, cyclobutane, cyclopentane, cyclohexane, etc. The larger cycloalkanes, with greater than 20 carbon atoms are typically called cycloparaffins.

Cycloalkanes are classified into small, common, medium, and large cycloalkanes, where cyclopropane and cyclobutane are the small ones, cyclopentane, cyclohexane, cycloheptane are the common ones, cyclooctane through cyclotridecane are the medium ones, and the rest are the larger ones.

Cycloalkanes are similar to alkanes in their general physical properties, but they have higher boiling points, melting points, and densities than alkanes.

8.Translate the sentences given.

1.Углеводороды могут быть газами (например, метан и пропан), жидкостями (например, гексан и бензол), восками или низкоплавкими твердыми веществами (например, твердый парафин и нафталин).

2.Алканы – это типы органических углеродных соединений, которые имеют только одинарные химические связи в своей структуре.

3.Пропан подвергается реакциям горения подобно другим алканам. При наличии избытка кислорода, пропан горит с образованием воды и двуокиси углерода. Когда кислорода в реакции присутствует недостаточно, происходит неполное сгорание, и пропан горит с образованием воды, окиси углерода, двуокиси углерода и углерода.

4.Ароматические соединения играют очень важную роль в промышленности. Ключевыми ароматическими углеводородами с экономической точки зрения являются бензол, толуол, орто-ксилол (диметилбензол) и пара ксилол.

5.Примерно 35 миллионов тонн ароматических соединений производится каждый год. Их выделяют из сложных смесей, полученных путем переработки нефти или дистилляции каменноугольной смолы (дегтя) (coal tar); они используются для производства ряда важных химических веществ и полимеров, включая стирол (styrene), фенол, анилин (aniline), полиэстр и нейлон.

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TEXT 7. ALIPHATIC AND CYCLIC HYDROCARBONS

Two overarching chain type categories exist: Open Chain aliphatic compounds and Closed Chain cyclic compounds. Those in which both open chain and cyclic parts are present are normally classed with the latter.

Aliphatic compounds. The aliphatic hydrocarbons are subdivided into three groups (homologous series) according to their state of saturation: paraffins alkanes without any double or triple bonds, olefins alkenes with double bonds, which can be mono-olefins with a single double bond, di-olefins, or di-enes with two, or polyolefins with more. The third group with a triple bond is named after the name of the shortest member of the homologue series as the acetylenes alkynes. The rest of the group is classed according to the functional groups present.

From another aspect aliphatics can be straight chain or branched chain compounds, and the degree of branching also affects characteristics, like octane number or cetane number in petroleum chemistry.

Aromatic and alicyclic compounds. Cyclic compounds can, again, be saturated or unsaturated. Because of the bonding angle of carbon, the most stable configurations contain six carbon atoms, but while rings with five carbon atoms are also frequent, others are rarer. The cyclic hydrocarbons divide into alicyclics and aromatics (also called arenes).

Of the alicyclic compounds the cycloalkanes do not contain multiple bonds, whilst the cycloalkenes and the cycloalkynes do. Typically this latter type only exists in the form of large rings, called macrocycles. The simplest member of the cycloalkane family is the three-membered cyclopropane.

Aromatic hydrocarbons contain conjugated double bonds. One of the simplest examples of these is benzene, the structure of which was formulated by Kekulé who first proposed the delocalization or resonance principle for explaining its structure. For "conventional" cyclic compounds, aromaticity is conferred by the presence of 4n + 2 delocalized pi electrons, where n is an integer. Particular instability (antiaromaticity) is conferred by the presence of 4n conjugated pi electrons.

The characteristics of the cyclic hydrocarbons are again altered if heteroatoms are present, which can exist as either substituents attached externally to the ring (exocyclic) or as a member of the ring itself (endocyclic). In the case of the latter, the ring is termed a heterocycle. Pyridine and furan are examples of aromatic heterocycles while piperidine and tetrahydrofuran are the corresponding alicyclic heterocycles. The heteroatom of heterocyclic molecules is generally oxygen, sulfur, or nitrogen, with the latter being particularly common in biochemical systems.

Rings can fuse with other rings on an edge to give polycyclic compounds. The purine nucleoside bases are notable polycyclic aromatic heterocycles. Rings can also fuse on a "corner" such that one atom (almost always carbon) has two bonds going to one ring and two to another. Such compounds are termed spiro and are important in a number of natural products.

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Tasks on the text

1.Memorize the following words and word combinations.

1) aliphatic [	] compound	11)	to confer [		] – давать,
– алифатическое соединение,			предоставлять
ациклическое соединение		12)	integer [`		] – целое,целое число
2) cyclic [	] compound–	13)	substituent [		] –
циклическое соединение			заместитель; замещающий атом;
3) octane number (rating) –			замещающая группа
октановое число (бензина)		14)	exocyclic – экзоциклический
4) cetane [	] number –	15)	endocyclic – эндоциклический
цетановое число		16)	heterocycle [		] –
5) aromatic compound –			гетероциклическое соединение
соединение ароматического ряда		17)	pyridine [		] – пиридин
6) bond(ing) angle – угол связи		18)	furan [		] – фуран
7) to propose – предлагать		19)	piperidine [		] – пиперидин
8) delocalization		20)	to fuse – объединяться, сливаться,
[	] –		смешиваться, соединяться
делокализация		21)	purine [		] nucleoside
9) conventional [	]		[`	,	] base –
– обычный, стандартный			пуриннуклеозидное основание
10) aromaticity – содержание		22)	spiro [`		] – спиральный
ароматических соединений

2.Translate the following word combinations.

State of saturation, straight (branched) chain compounds, from another aspect, stable configurations, conjugated, two bonds going to one ring and two to another.

3.Read the text and answer the questions given.

1)What two overarching categories of hydrocarbon compounds exist? What principle is their classification based on? What is the difference between cyclic compounds and aliphatic ones?

2)Into what groups and according to what principle are aliphatic compounds subdivided?

3)What are mono-olefins, di-olefins (di-enes) and poly-olefins?

4)What is the difference in the configuration of straight chain and branched chain compounds?

5)What is the principle of the configuration of the cyclic compounds? How many carbon atoms can they contain?

6)What groups are cyclic hydrocarbons divided into?

7)What are mycrocycles?

8)What bonds do aromatic hydrocarbons contain?

9)What provides the states of aromaticity and antiaromaticity?

10)What is a heterocycle ring?

4.Draw a hierarchical scheme of hydrocarbon compounds classification.

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5.Find suitable definition for each of the words given.

1)	alicyclic (compound);	6)	piperidine;	11)	Kekulé formula;	16)	alkane;
2)	aliphatic (compound);	7)	pyridine;	12)	cyclopropane;	17)	alkene;
3)	heterocyclic (compound);	8)	benzene;	13)	benzene ring;	18)	alkyne.
4)	cyclic(compound);	9)	aromaticity;	14)	purine;
5)	aromatic (compound);	10)	cetane	15)	furan;

1.A compound, not aromatic, esp. having an open chain structure, such as alkanes, alkenes, and alkynes.

2.A compound containing a closed saturated or unsaturated ring of atoms.

3.Any saturated aliphatic hydrocarbon with the general formula CnH2n+2.

4.Any unsaturated aliphatic hydrocarbon with the general formula CnH2n. Also called: olefine, olefin.

5.Any unsaturated aliphatic hydrocarbon that has a formula of the type CnH2n-2.

6.A compound having an unsaturated ring containing alternating double and single bonds, esp. containing a benzene ring.

7.A compound having aliphatic properties, in spite of the presence of a ring of carbon atoms.

8.A colourless flammable gaseous hydrocarbon, used in medicine as an anaesthetic; trimethylene. It is a cycloalkane with molecules containing rings of three carbon atoms. Formula: C3H6; boiling pt.: -34°C.

9.A colourless flammable toxic aromatic liquid used in the manufacture of styrene, phenol, etc., as a solvent for fats, resins, etc., as an insecticide. Formula: C6H6.

10.A representation of the benzene molecule as six carbon atoms at the corners of a regular hexagon with alternate double and single bonds joining them and with one hydrogen atom bound to each carbon atom.

11.The hexagonal ring of bonded carbon atoms in the benzene molecule or its derivatives.

12.The property of certain planar cyclic conjugated molecules, esp. benzene, of behaving like unsaturated molecules and undergoing substitution reactions rather than addition as a result of delocalization of electrons in the ring.

13.A colourless hygroscopic (гигроскопический (легко поглощающий влагу)) liquid with a characteristic odour. It is a basic heterocyclic compound containing one nitrogen atom and five carbon atoms in its molecules and is used as a solvent and in preparing other organic chemicals. Formula: C5H5N.

14.A compound containing a closed ring of atoms, at least one of which is not a carbon atom.

15.A colourless liquid heterocyclic compound with a peppery ammoniacal odour: used in making rubbers and curing epoxy resins. Formula: C5H11N.

16.A colourless flammable toxic liquid heterocyclic compound, used in the manufacture of cotton textiles and in the synthesis of nylon. Formula: C4H4O.

17.A colourless crystalline solid prepared from uric acid. Formula: C5H4N4.

18.A colourless insoluble liquid alkane hydrocarbon used in the determination of the cetane number of diesel fuel. Formula: C16H34

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