CHEM LAB 4

soluble in H2O

small & polar molecule

insoluble in H2O

large & neutral molecule

soluble in NaHCO3 (weak base)

strong acid (carboxylic acid)

soluble in NaOH (S. base)

weak acid (phenol & carboxylic acid)

soluble in HCl (S. acid)

weak base (amine)

insoluble functional groups

ketones, aldehydes, esters, & alcohols

why dont strong acids dissolve in strong bases?

they would neutralize (decimate their defining property)

ceric test is for

OH/Ph

what can give a false negative in ceric test?

alcohols with > 10C

for ceric test, if the unknown isnt H2O soluble, what do you use?

1,4-dioxane or diethyl ether

(+) result on ceric test

color change (red for OH and brownish green for Ph) & precipitate

oxime test is for

aldehydes & ketones

why doesny oxime test work on carboxylic acids/derivatives?

form amide

why use isopentyl nitrite to generate diazonium ion rather than sodium nitrite?

sodium nitrite is insoluble in dimethoxyethane

why is LiAlH4 is bad red. agent than NaBH4?

IS VERY REACTIVE & DECOMPASES METHANOL

How does the GC-MS determine which product you made?

software compares fragmentation pattern of the cmpd to its database

why different H ppm for same ortho NH2 in webmo? (6.5 & 7.1)

looks at invidual H’s instead of how they react and average it out (1 confomation where H’s are different; 6.8 ppm)

(+) result on oxime test

precipitate

ferric test is for

phenol & ester

what can give a false + on ferric test?

carbonyls that readily taut. to enols

(+) result from ferric test

1. color change for phenol

2. colored solid forming for ester

(MS) how to know if the compound has N in it?

odd MW

(MS) how to know if the compound has Br in it?

1:1 at M & M+2 (Br-79 & Br-81)

(MS) how to know if the compound has Cl in it?

3:1 at M & M+2 (Cl-35 & Cl-37)

(MS) how to find the # C13 in a given compound?

M+1/M intensity ratio → ratio/1.1% (since c12= 98.9% abundant while C13= 1.1%; pick the peak with highest m/z and another next to it)

tollens test is for

aldehydes (ald oxidized to carboxylic acid)

why destroy unused reagents for tollens’ test?

produce explosive silver fulminate

(+) result for tollen’s test

silver precipitates (mirror)

Nitrous test is for

1 & 2 amines

why cant teritary amines participate in nitrous test?

cant form diazonium ions to be released (no H and all R groups that occupy)

what could give a false + for nitrous test?

ketones & phenols

just based on solubility, cerium & ferric test, which function groups can be uniquely identified?

ester, amines, carboxylic acids

TMS

0 PPM

which core functional groups can be uniquely identifies based on the C=O and OH/NH region of the IR spectrum?

aldehydes & carboxylic acids

why arent any of the amines tertiary?

reactive or unpredictably reactive with nitrous acid & acyl chloride

useless IR N-H peak

why H2O bad solvent in lab 1?

camphor insoluble in H2O & it decomposes the NaHBH4

safety hazard of lab 3

isopentyl nitrite is vasodilator & causes shortness of breath

can you compare 2 different compound G?

NO

why do aldehyde give false positive in ferrous test?

can be oxidized to OH

in WEBMO 1&3 carbocation had exact same energy; why not count as primary carbocation being stable?

1 carbocation did hydride shift to be 3; not accurate energy