中
有效日七初月二年未辛腦窺
譽鐵:
報學肴賣
B
1674
Chemistry (25)
1991 +**MISZE
明流出版社—
MILL & DATE PRESS
Unit 14 (Continued).
3. Summary of chemical properties
報日僑
Oxidising agents commonly used are:
(1)acidified KMnD (Chronic acid}
(2)acidified Kyrgy
(3)copper at 250°C
五期
日二廿月三(一九九一)年十八國民蘊中(2日)
Thermomotor
Distilling
flesk
Receiver
Mixture P and
cone N4504.
Alkanes
1. Preparation By heating sodium alkanoate with soda lime.
Acba "Na*
Sndlun alkangate
+ маон RI+ Na2CO3
Soda ime 15.8 solid mixture of quicktime (Ca) and NaOH. e.g. CH2COONa+ NaOH CH2+ Na2CO2
CH2CCOONa+ NaOH
2. Reactions
CH3CH, Na2CO3.
Alkanes are rather chemically unreactive. Under ordinary conditions; they are inert to acids, bases, reducing or oxidising agents, etc. (a)Combustion burning in air with a slightly luminous flame, giving
Co2 and steam.
2+2+02
NCO2+ {n+1}H2O
CU or C is formed if oxygen is insufficient.
e.g. CH2+ 207
CO2+ 2420
2CH302 ---- 200+ $20 CH2+ O2
(b)Substitution reaction
C =
* 2420
Alkanes are saturated hydrocarbons, f.e. all their bonds are single. bonds. The H-atoms in alkanes can be substituted by halogen atoms in the presence of sunlight. Alkane + X2
Halogens alkanes + HX direct sunlight
X: Cl, Br,
diffused light.
CH2- Cl2
in darkness
explosive reaction smooth reaction: no reaction
W. LAM
9.9. CH2CH2OH + 2(0)
-CH-COOH
Ethanoic acid
Alkanoic acids
1. Preparation By Oxidation of alkano!s
Alkanal
Alkanoic acid
..
Mo
Oxidising agents used:
Kling/*
or X2Cr207/
e.. CH3CH2CH2OH + 2(0)
Propan-1-01
+ H2O
Propanoic acid
2. Reactions
(a)As a weak acid
Alkanoic acids, when dissolved in water, are slightly vanized to give hydronium ions (H0) that are responsible for acidic properties.
Alkanoic acid + H2O = Alkangate Ton`
Thus, they exhibit many properties typical of acids. They are
momobasic acids.
e.g. (1) CH3COOH + H2OCH ̧¢00* + H20*,
Heat
water.
Water-bath
Ethyl propanoste
(a) Give the structural formula of
ethyl propanoate.
(b) Name THO compounds which are most probably contained in the mixtura PM
(c) Write an equation of the formation
of ethyl propanoate.
(d) State-
TWO
functions concentrated sulphuric
this experiment.
∙of the
acid.
in
(e) Give the name of the apparatus Y in
the diagram.
(f) Which of the two openings, A and 8,
Is the water inlet?
(g) (1). What
On
would
be obtained heating some ethyl propanoate with sodium hydroxide solution? (2) Write an equation of the
reaction.
(3) What type. of reaction' is this? (h) Why is the receive immersed in the
cold water?
(2) 2CH2COOH + Mg
(3) 2CH3COOH + NACO
(4} CH,GOOH + NaNH
Mg(CH2C00)2+ H2
2CH,000 ̃Ha* + H2B +CO2
(b)Ester 'formation — a condensation reaction
·CH2Cap Na* + H2O
H* catalyst
Alkanoic acid Alkahoi
Ester
(fragrant smell)
Thus, light as necessary for the reaction to take place, so, it is a photochemical reaction. The reaction between CH, and Cl2 is
given below.
→→→ HCT CH2C1 (monochloromethane)
..CH1 + Cl2.
·CH2C1 → C12.
HETCHE (dichloromethane)
HCT CRC (trichloromethane}
CH2Cl2+ Cl2
CHC1C12 HOT CE34 (tetrachloromethane)
(c)Thermal cracking
large alkanes Catalyst simpler
A
simpler alkanes alkenes
(N.B. This an important industrial method of obtaining alkenes from
petroleum.).
1273k
Peth + 2H2 (Pyrolysis)
But, CHA
conc. H250
Alkenes
1. Preparation - By dehydration of alkanals.
{Alkano) Dehydrating agent [Alkanal+ H20
Dehydrating agents commonly used are:
(a)hot, unglazed porcelain (using alkano) vapour
(b)conc. H2504 (excess, at 175°C to 180°C),
(c)hot Alumina (Al0g), ̈ ̈
(d)phosphoric acid.
6.9. CH CH201
2. feactions
众
combustion → burning with a smoxy Fiume, giving Co2 and steam onl C2302
•*•g, CH2 = CH2+ 30, 2002 24,0
(biscdition converting unsaturated compounds to
Examples
HONG KON
(1)With halogens(X) - rapid decolourization, forming
1681
1685
1688
· Cl2 = CH2 X2
$5390 $5690
$6490
$ 7290
A大酒店
子
-CH2CH2X
X: Cl, Br, I.
(2){th hydrogen halides (HX).
(3)Catalytic hydrogenation
· CH2 # CH2 + H2
(4)ith conc. 1250
CHCH
Ni or Pt
CH2CH3
CH2- CH2+ K - HSO CH2CH2HSO
CHCH2HSO4 + H2O
(c)Oxidation
180°C
CH2CHHH2SO
Acidified EMAD is decolourized by alkenes.
CH2 CH2 + (0) + Hyla CH CHO
(d)Polymerization
OH
ethane-1, 2-diol
the A-C - OH + C
CH-CH2o where &
denotes alkyl groups. The reaction is reversible. e.g. CH2COOH + C2HOCHCOC
+ H2O
Ethyl ethanoate
(c)With chlorides of phosphorus (PC), or
and.
White fures of HC1(9) are seen and an alkanoyl chlaride is Formed, Alkanoic acid PC15
Alkanoy! chloride
+ POCI + HCT
e.g. CH2CON + PC75
CH2C - CT = HCP
Ethanoy?
共
Tests
anes
no spe
(a) Rapid
bromine
bromine
Alkenes
(Br2/CC14)
test.
chloride
te the reagents and conditions essary for each of the following
conversions. Write an equation of
圖
decolourization of water (Br2/H20) or
in tetrachloromethane
(b) Rapid decolourization of
acidified
potassium
permanganates [KMnO4/HT);
4.3 Alkanols
(a) Smell e.g. CH CH and CHOH.
~*(b) during with a blue flame.
(c) Forming fruit-smelling ester
with an alkanoic acid.
(d) Evolving H2 gas on
sodium metal.
4.4 'Alkanoic acids
(a) Evolving
Seach conversion.
ii. X
iii. X
iv.
(d) Write
equation of
between P and brutisa interachlorometha
Question 14.2
reaction Iution
An organic liquid X has the structural „formula as shown below..
adding
X:
CH3
gas on
adding
aqueous
ester
magnesium to the solution of the acid.
(b) Forming fruit-smelling
with an alkañol.
5. Uses
5.1 Alkanes
(a) as fuels.
CH2
- CH - CH2OH
(a) Name the compound X
the IUPAC systems.
IES
Solution to Q.14.1,
(a) P is an alkene.
Q.is an alkanoic acid. (b) X is propan-1-ol (CH2CH2CH2OH)
(It could not be propan-2-01
because this compound would not be oxidized to an acid having the same. number of carbon atoms.) .P.is propene..
Q is propanoic acid.
R is 1-chloropropane.
Sis ethyl ethanoate.
(c) t. Excess conc H250/Heat to 180°C..
CH2CH CH2OH
.=
+
CHỊCH Chi Ngo
ii. Acidified KMnO/Heat.
CH3CH2CH2OH
+2(0)
CH2CH2COOH + H2O
iii. PC/No heating required.
CH2CH2CH2O + PC15
CH3CH2CH2C+ POC13 + HCT
iv. Ethanoic acid (CH-COOH), conc
H2$04/Heat,
CHCH2CH2OH + CH3COOH'
CHCOOCHCH2CH3 + H2D
(b) CH2CH=CH2+ Brz
Solution to Q.14.2
CH2CHBRCH Br
(a) X is 2-methylpropan-1-01.
(b) CH CH2CH2CHCH
Butan-1-ol
to
CH3CH2CHCH3
Butan-2-ol
CH3
CH2
CH3
(b) There are THREE of compounds
isomeric to X and having
many properties similar write out their structural formulae and name them accordion. systems.
BR
the IUPAC
(c) Describe withould you observe and write an appropriate equation of thet reaction on adding the folding substances separately into X.
KONG PUBLIC
Since an alkene molecule consists of carbon-carbon double bond, s0, under high-temperature and pressure it can jola to one another to form long chains of polymar by addition reaction.
a little 02 as catalyst a.g. nth2 = Cily heat, high pressure
0.9.
or
Atkanois
+CH2- CH2++ polythene
CH3CH2 - #50
Ethanol + CO2 + energy
26°C. - 36°C
1. Preparation
(a)By hydration of alkanes
CH2 = CH2+ H2SO4 CH3CH2- HSO4 + 2SO~~~~ CECH2OH + H2501
(b)0y fermentation of sugar to give ethanol
Hydrolysis glucose Yeast Enzymas
fructose
Sugar
2. Reactions
(a)Combustion
CnH2n+++
30
e.g. C2H5OH + 302
(b)With very reactive metals (e.g. K, Naj – Hydrogen yas is liberated
and alkanols act.as weak acids.
•n€02 + [n+1]H20, AH - -va
2002 + 3H20
Alkanola -------
sodiure
Alkoxide
e.g. Catizo la
+
+ H2
Call50*a*
+ Hą
sudium
(c)With chlorides of phosphorus (PC1, and FC1g)
3)
· obtained.
Milte misty fumes of HC1 (g) are seen and a chloroalkane is
e.g. C2NO + PG15.
chloroethene
POC13 + HC
(d)Dahydration-converting alkanols to alkenes
Alkanot Dehydrating agent Alkene +
1420
Conc H2504
e.g. C2500
~~~CH2 = CH2 + N2O
180°C
(0)
(0)
Alkanal
{a}uxidation
Alkanol
Alkanoic acid
b) as organic solvents.
5.2 Alkenes
As raw materials of many plastics, e.g. ethene for making polyethene.
5.3 Alkanols
(a) Ethanol in alcoholic drinks.. (b) As organic solvents, e.g. CH2OH for points and dyes; C2H5OH for cosmetics and perfumes, etc.
(c) As fuels in spirit lamps.
(d) in manufacture of synthetic
fibres. ethanoic acid esters.
5.4 Alkanoic acids
(1) Ethanoic acid in vinegar.
1. A small piece of sodium metál. it. A few drops of phosphorus(v)
chloride.
(d) In the experiment as shown below, compound X is vapourized and passed over some hot broken porcelain. A`· colourless gas. Y is formed and passed separately into the bromine water and the acidified potassium permanganate solution by means of a 3-way tap..
and
Broken porcelain
Gas Y
3-way tap
(2) In manufacture of esters, dyes, artificial silk, drugs, etc.
(3) Congulation of rubber latex.
Question 14.1
A simple alkanol K has a molecular formula CH. On suitable treatments X can be converted separately to compounds P, Q, R and $ in one step. .P, Q and A contain the same number of
carbon atoms as X.
P
5
Q
X
(C51002)
A Chloroalkane
P can decolourize bromine solution in tetrachloromethane.
Q can turn a wet pH paper red.
S is a sweet-smelling liquid, insoluble in water.
Q
(a) State the names of the homologous series to which P and respectively belong.
(b) Identify and name, according to the IUPAC systems, the compounds X, P. Q. R and S.
Host
Cotton soaked " with liquid X
ON-
2-methylpropan-2-ol
(c) i. Effervescence occurs.
given off.
21 CH3CHCH2OH+ 2Na
as H2 is
• 2 (CH3)2CH2CH2O ̃Na* + H2
ii. White fumes hydrogen chloride
are seen.
(CH3)2CHCH2OH + PC15
(CH3)2CHCH2C)
+
POCI3
+ HC1
(d) i. (1) Y is 2-methylpropene. (2) (CH)CHCH2OH
(CH3)2CH = CH2
+
H20
water
is
if. It dehydrates the alkano? X.
iii. (1) Bromine
decolourized.
(2) It is an addition reaction.
2
(3) (CH3)2CH = CH2 + Br
(CH3)2CHBrCH Br
solution
decolourized. (2) It is an oxidation,
Bromine water
Acidified KMnO4
iv. (1) The
1. (1) What is gas Y?
(2) Write an equation of its
formation.
the
11. What is the function of
broken porcelain? iii. (1) What happens to the browing
water?
(2) What type of reaction is
this?
(3) Write an equation of the
reaction?
iv. (1) What happens
acidified
permanganate?
to the potassium
(2) What type of reaction is
this?
Question 14.3
In the experiment below a-mixture P and a little of concentrated sulphuric acid After was rofluxed using a waterbath. some while, ethyl propanoate, a sweet- swelling liquid collected in the receiver,
Solution to 0.14.3
of ethyl
(a) The structural formula
propanoate is CH,CH2COOCH2CH2,
(b) The two compounds are propanoic
acid and ethanol.
(c) CH2CH2E001 + CH]£H2OH •
CH2CH2COOCICH2+ H2O
(d) Conc #2S04 acts as a catalyst and a
dehydrating agent.
(e) Y is the Liebig condenser. (f) is the water inlet.
(g) 1.
Sodium propanoate and ethanol are obtained. i. It is the alkaline hydrolysis
of ester.
1. CH2CH2COOCHCH2 + NaOH →→
+
CH2CH2.
(b) This is to reduce the vapourization
of liquid ethyl propanoate.