Based upon its reaction with water, what is another acceptable name for calcium carbide?
Calcium Acetylide
write down the section between cac2 and water table the conjugated acid-base paris. which one is the stronger acid which one is the stronger base?
CaC2 + 2H2O-------> C2H2 + Ca (OH) 2
ca(oh)2-conjugate base
ca(oh)+ conjugate acid
c2h2-conjugate acid
c2h conjugate base
Write down the reaction between acetylene and potassium permanganate
3C2H2(g) + 8 MnO4 (aq) + 8H+(aq) ------> 3Hcooh (aq)+3C02(g)+8MnO2(s) + 4 H2O(I)
Write down the reactions for the formation of Cu2C2 and Ag2C2
C2H2+2AgOh ----> Ag2C2+2H20
C2H2+2CU+----->C2 CU2 +2H+
Alkynes Chemical Properties
Combustion of Alkynes
Ethyne burn in air with a luminous, smoky flame, (forming carbon dioxide and water).
2 C2H2 + 5 02 ==> 4 CO2 + 2 H2O
The ethynes are highly dangerously explosives when mixed with air or oxygen.
Oxidation of Alkynes
Ethyne is oxidised
Alkynes Physical Properties
Alkynes are compounds which have low polarity, and have physical properties that are essentially the same as those of the alkanes and alkenes.
They are insoluble in water.
They are quite soluble in the usual organic solvents of low polarity (e.g. ligroin,
How to make acetylene
acetylene is conveniently prepared by the hydrolysis of calcium carbide, CaC2, according to the equation:
CaC2 + 2H2O-------> C2H2 + Ca (OH) 2
how to make butanone
Oxidation of 2-butanol is one way to produce butanone. Butanone is produced by the dehydrogenation of 2-butanol using a catalyst based on copper, zinc, or bronze:
CH3CH(OH)CH2CH3 ? CH3C(O)CH2CH3 + H2
how to make pentane
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how to make 2-pentane
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Features for SN1:
(1) Rate = k[RX]
(2) RX reactivity is: 3o � 2o � 1o
(3) Rearrangements occur
(4) Favored by POLAR protic solvent
(5) Favored by WEAK nucleophile
(6) Racemization at chiral center
General mechanism: step 1: R-X --- (slow) --- � R+ + X- (slowest)
step 2: R+
Features for SN2:
(1) Rate =k [RX] [Nucleophile]
(2) RX reactivity: CH3 X> 1o > 2o >3o
(3) No rearrangements occur
(4) Favored by POLAR, aprotic solvent
(5) Favored by STRONG nucleophile
(6) Complete INVERSION at chiral center
General Mechanism: Nu: + R-X ?[Nu ... R...X]?
Reaction with AgNO3 in ethanol (SN1)
In this experiment, alcoholic silver nitrate solution will be used to react with various alkyl halides. This solution is composed of the fairly polar protic alcohol solvent and the very weak nucleophile, the nitrate ion. Thus, SNI reaction is favored.
Reaction with Nal in acetone (SN2)
Sodium iodide dissolved in acetone creates an appropriate condition favoring SN2 reactions. The iodide is a very strong nucleophile.
Reaction is noted by the appearance of AgX precipitate
AgNO3 (alc) + R-X ----� AgX? + R-NO3
List the reaction rate order (from the fastest to the slowest) for Part A. (favoring SN1)
T-butyl Chloride, 2-Chlorobutane, 1-bromobutane, 1-chlorobutane, 1-bromooctane, benzyl Chloride, chlorobenzene.
List the reaction rate order (from the fastest to the slowest) for Part B. (favoring SN2)
Benzyl Chloride, 1-Bromooctane, 1-Bromobutane , 1-chlorobutane, T-butylchloride, chlorobenzene
Write a general reaction equation for part A.
R-X + Ag(No3) ----> Agx +R-No3 (white precipitate)
Write a general reaction equation for part B
NAI+ R-X ---->NaX+ R-I (precipitate)
For part A, what is your observation on the reaction rates from the following factors based experimental results? (For example, 1-brombutane reacted fasted than 1-chlorobutane, therefore, Br is a better leaving group than Cl.)
a. Nature of halogens (leavi
in the nature of halogens, the leaving group Br is better than Cl because Br is a weaker base. 1-bromo reacated faster than 1-chlorobutane
The length of carbon chain in RX (compare 1-brombutane and 1-bromooctane)
1-bromobutane and 1-bromooctane are both primary but the 1-bromo-octane has a longer carbon chain, which is the reason why the 1-bromooctane reacted faster than the 1-bromo-butane. the rate of the reaction in the SN2 depends on both the (RX) AND THE NUCLE
Arylic (Vinyl) and benzylic (allylic) halides (compare chlorobenzene and benzyl chloride)
in a vinyl halides, the halogen is directly attached to a spa carbon. in the allelic halides, the halogens is directly attached to a spa carbon and that is attached to a spa carbon. also allylic is more stable than the vinyl halides. benzyl chloride has a
Primary, secondary and tertiary RX (compare 1-chlorobutane, 2-chlorobutane
and t-butyl chloride)
comparing all three chlorobutane, 2-chlorobutane, t-butychloride appears to be fast and stable to react all 4 carbon chain and tertiary. t-butyl chloride has a tertiary carbon which favored the sn1. in T-butal it reacted faster than the 1-chlorobutane and
For part B, what is your observation on the reaction rates from the following
factors based on experimental results?
a. Nature of halogens (Cl, Br) (compare1-brombutane and 1-chlorobutane)
the reaction of 1-bromobutane happens faster than the 1-chlorobutane, reaction did not occur for the 1-chlorobutane. which makes bromine a better leaving group
The length of carbon chain in RX (compare 1-brombutane and 1-bromooctane)
the reaction of 1-bromooctane occurred faster than the 1-bromobutanee because the longer the carbon chain is the father the reaction will happen.
Arylic (Vinyl) and benzylic (allylic) halides (compare chlorobenzene and benzyl chloride)
the chlorobenzene did not react. the benzyl chloride reacted really fast. that proved the vinyl halides does not react within the sn2 reaction while the allylic halides does.
Primary, secondary and tertiary RX (compare 1-chlorobutane, 2-chlorobutane
and t-butyl chloride)
sn2 favored primary so the reaction happened. 1-chlorobutane was suppose to occur the fastest followed by the 2chlorobutane and t-butal chloride
What exactly does the IR spectrum measure?
the IR spectrum measures absorbance or resonance with radiation of specific frequency
What THREE rules should be applied to all analyses?
(1) Carefully note what absorbance are present in the higher energy region, (above 1250 cm-1)
(2) Place as much importance on absorbances that are NOT present as on those which are.
(3) Include all aborbances for each functional group. For example; for C-
(3) What are the distinguishing absorbances for the following ?
(a) saturated alkanes - the fictional group contains only a single bond
(b) alkenes-this functional group contains carbon-carbon double bonds and peaks on IR
(c) alkynes- THIS FUNCTIONAL GROUP Contains carbon-carbon triple bond.
(d) aromatic hydrocarbons-
How are PRIMAR, SECONDARY, TERRIARY and AROMATIC ALCOHOLS
distinguished in the IR spectrum?
(b)how are they similar?
the peak determines how they are distinguished , primary appears from 1075-1000cm-1, secondary, it appears between 1150-1075cm, for tertiary, it appears to be between 1210-100cm-1 and for aromatic it appears to be 1230s.
they are similar- the range of all
A strong absorbance around 1700 cm-1 is characteristic of the C= 0 bond feature. Which FUNCTIOINAL GROUPS will give this absorbance?
the fuctional groups that will give this absorbance is the carbonyl compounds such as alaehyis, ether, ketones, and amides which gives a very strong, sharp peak.
Which bonds show absorbances between 3000 and 4000 cm-1?
Alkenes=C-H (Stretch) band position 3020-3100m
alkynes C-H (STRETCH) BAND position 3300s
alcohols = o-h(stretch) band position 3300-34cos,b
h-bonded
nonbonded 3610s
aromatic c-h(stretch) band position 3030m
amines N-H (stretch) bandposition 3310-3500m